Peptic Ulcer Disease
Burning epigastric pain exacerbated by fasting and improved with meals is a symptom complex associated with peptic ulcer disease (PUD). An ulcer is defined as disruption of the mucosal integrity of the stomach and/or duodenum leading to a local defect or excavation due to active inflammation. Ulcers occur within the stomach and/or duodenum and are often chronic in nature. Acid peptic disorders are very common in the United States, with 4 million individuals (new cases and recurrences) affected per year. Lifetime prevalence of PUD in the United States is approximately 12% in men and 10% in women. Moreover, an estimated 15,000 deaths per year occur as a consequence of complicated PUD. The financial impact of these common disorders has been substantial, with an estimated burden on health care costs of >$15 billion per year in the United States.
Despite the constant attack on the gastroduodenal mucosa by a host of noxious agents (acid, pepsin, bile acids, pancreatic enzymes, drugs, and bacteria), integrity is maintained by an intricate system that provides mucosal defense and repair.
The gastric epithelial lining consists of rugae that contain microscopic gastric pits, each branching into four or five gastric glands made up of highly specialized epithelial cells. The makeup of gastric glands varies with their anatomic location. Glands within the gastric cardia comprise <5% of the gastric gland area and contain mucous and endocrine cells. The majority of gastric glands (75%) are found within the oxyntic mucosa and contain mucous neck, parietal, chief, endocrine, and enterochromaffin cells (Fig. 285-1). Pyloric glands contain mucous and endocrine cells (including gastrin cells) and are found in the antrum.
The parietal cell, also known as the oxyntic cell, is usually found in the neck, or isthmus, or the oxyntic gland. The resting, or unstimulated, parietal cell has prominent cytoplasmic tubulovesicles and intracellular canaliculi containing short microvilli along its apical surface (Fig. 285-2). H+, K+-ATPase is expressed in the tubulovesicle membrane; upon cell stimulation, this membrane, along with apical membranes, transforms into a dense network of apical intracellular canaliculi containing long microvilli. Acid secretion, a process requiring high energy, occurs at the apical canalicular surface. Numerous mitochondria (30 to 40% of total cell volume) generate the energy required for secretion.
Gastroduodenal Mucosal Defense
The gastric epithelium is under a constant assault by a series of endogenous noxious factors including HCl, pepsinogen/pepsin, and bile salts. In addition, a steady flow of exogenous substances such as medications, alcohol, and bacteria encounter the gastric mucosa. A highly intricate biologic system is in place to provide defense from mucosal injury and to repair any injury that may occur.
The mucosal defense system can be envisioned as a three-level barrier, composed of preepithelial, epithelial, and subepithelial elements (Fig. 285-3). The first line of defense is a mucus-bicarbonate layer, which serves as a physicochemical barrier to multiple molecules including hydrogen ions. Mucus is secreted in a regulated fashion by gastroduodenal surface epithelial cells. It consists primarily of water (95%) and a mixture of lipids and glycoproteins. Mucin is the constituent glycoprotein that, in combination with phospholipids (also secreted by gastric mucous cells), forms a hydrophobic surface with fatty acids that extend into the lumen from the cell membrane. The mucous gel functions as a nonstirred water layer impeding diffusion of ions and molecules such as pepsin. Bicarbonate, secreted by surface epithelial cells of the gastroduodenal mucosa into the mucous gel, forms a pH gradient ranging from 1 to 2 at the gastric luminal surface and reaching 6 to 7 along the epithelial cell surface. Bicarbonate secretion is stimulated by calcium, prostaglandins, cholinergic input, and luminal acidification.
Surface epithelial cells provide the next line of defense through several factors, including mucus production, epithelial cell ionic transporters that maintain intracellular pH and bicarbonate production, and intracellular tight junctions. If the preepithelial barrier were breached, gastric epithelial cells bordering a site of injury can migrate to restore a damaged region (restitution). This process occurs independent of cell division and requires uninterrupted blood flow and an alkaline pH in the surrounding environment. Several growth factors including epidermal growth factor (EGF), transforming growth factor (TGF) , and basic fibroblast growth factor (FGF) modulate the process of restitution. Larger defects that are not effectively repaired by restitution require cell proliferation. Epithelial cell regeneration is regulated by prostaglandins and growth factors such as EGF and TGF-. In tandem with epithelial cell renewal, formation of new vessels (angiogenesis) within the injured microvascular bed occurs. Both FGF and vascular endothelial growth factor (VEGF) are important in regulating angiogenesis in the gastric mucosa.
An elaborate microvascular system within the gastric submucosal layer is the key component of the subepithelial defense/repair system. A rich submucosal circulatory bed provides HCO3-, which neutralizes the acid generated by parietal cell secretion of HCl. Moreover, this microcirculatory bed provides an adequate supply of micronutrients and oxygen while removing toxic metabolic by-products.
Prostaglandins play a central role in gastric epithelial defense/repair (Fig. 285-4). The gastric mucosa contains abundant levels of prostaglandins. These metabolites of arachidonic acid regulate the release of mucosal bicarbonate and mucus, inhibit parietal cell secretion, and are important in maintaining mucosal blood flow and epithelial cell restitution. Prostaglandins are derived from esterified arachidonic acid, which is formed from phospholipids (cell membrane) by the action of phospholipase A2. A key enzyme that controls the rate-limiting step in prostaglandin synthesis is cyclooxygenase (COX), which is present in two isoforms (COX-1, COX-2), each having distinct characteristics regarding structure, tissue distribution, and expression. COX-1 is expressed in a host of tissues including the stomach, platelets, kidneys, and endothelial cells. This isoform is expressed in a constitutive manner and plays an important role in maintaining the integrity of renal function, platelet aggregation, and gastrointestinal mucosal integrity. In contrast, the expression of COX-2 is inducible by inflammatory stimuli, and it is expressed in macrophages, leukocytes, fibroblasts, and synovial cells. The beneficial effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on tissue inflammation are due to inhibition of COX-2; the toxicity of these drugs (e.g., gastrointestinal mucosal ulceration and renal dysfunction) is related to inhibition of the COX-1 isoform. The highly COX-2-selective NSAIDs have the potential to provide the beneficial effect of decreasing tissue inflammation while minimizing toxicity in the gastrointestinal tract (see below).
Physiology of Gastric Secretion
Hydrochloric acid and pepsinogen are the two principal gastric secretory products capable of inducing mucosal injury. Acid secretion should be viewed as occurring under basal and stimulated conditions. Basal acid production occurs in a circadian pattern, with highest levels occurring during the night and lowest levels during the morning hours. Cholinergic input via the vagus nerve and histaminergic input from local gastric sources (see below) are the principal contributors to basal acid secretion. Stimulated gastric acid secretion occurs primarily in three phases based on the site where the signal originates (cephalic, gastric, and intestinal). Sight, smell, and taste of food are the components of the cephalic phase, which stimulates gastric secretion via the vagus nerve. The gastric phase is activated once food enters the stomach. This component of secretion is driven by nutrients (amino acids and amines) that directly stimulate the G cell to release gastrin, which in turn activates the parietal cell via direct and indirect mechanisms (see below). Distention of the stomach wall also leads to gastrin release and acid production. The last phase of gastric acid secretion is initiated as food enters the intestine and is mediated by luminal distention and nutrient assimilation. A series of pathways that inhibit gastric acid production are also set into motion during these phases. The gastrointestinal hormone somatostatin is released from endocrine cells found in the gastric mucosa (D cells) in response to HCl. Somatostatin can inhibit acid production by both direct (parietal cell) and indirect mechanisms [decreased histamine release from enterochromaffin-like (ECL) cells and gastrin release from G cells]. Additional neural (central and peripheral) and hormonal (secretin, cholecystokinin) factors play a role in counterbalancing acid secretion. Under physiologic circumstances, these phases are occurring simultaneously.
The acid-secreting parietal cell is located in the oxyntic gland, adjacent to other cellular elements (ECL cell, D cell) important in the gastric secretory process (Fig. 285-5). This unique cell also secretes intrinsic factor. The parietal cell expresses receptors for several stimulants of acid secretion including histamine (H2), gastrin (cholecystokinin B/gastrin receptor) and acetylcholine (muscarinic, M3). Each of these are G protein-linked, seven transmembrane-spanning receptors. Binding of histamine to the H2 receptor leads to activation of adenylate cyclase and an increase in cyclic AMP. Activation of the gastrin and muscarinic receptors results in activation of the protein kinase C/phosphoinositide signaling pathway. Each of these signaling pathways in turn regulates a series of downstream kinase cascades, which control the acid-secreting pump, H+, K+-ATPase. The discovery that different ligands and their corresponding receptors lead to activation of different signaling pathways explains the potentiation of acid secretion that occurs when histamine and gastrin or acetylcholine are combined. More importantly, this observation explains why blocking one receptor type (H2) decreases acid secretion stimulated by agents that activate a different pathway (gastrin, acetylcholine). Parietal cells also express receptors for ligands that inhibit acid production (prostaglandins, somatostatin, and EGF).
The enzyme H+, K+-ATPase is responsible for generating the large concentration of H+. It is a membrane-bound protein that consists of two subunits, and . The active catalytic site is found within the subunit; the function of the subunit is unclear. This enzyme uses the chemical energy of ATP to transfer H+ ions from parietal cell cytoplasm to the secretory canaliculi in exchange for K+. The H+,K+-ATPase is located within the secretory canaliculus and in nonsecretory cytoplasmic tubulovesicles. The tubulovesicles are impermeable to K+, which leads to an inactive pump in this location. The distribution of pumps between the nonsecretory vesicles and the secretory canaliculus varies according to parietal cell activity (Fig. 285-2). Under resting conditions, only 5% of pumps are within the secretory canaliculus, whereas upon parietal cell stimulation, tubulovesicles are immediately transferred to the secretory canalicular membrane, where 60 to 70% of the pumps are activated. Proton pumps are recycled back to the inactive state in cytoplasmic vesicles once parietal cell activation ceases.
The chief cell, found primarily in the gastric fundus, synthesizes and secretes pepsinogen, the inactive precursor of the proteolytic enzyme pepsin. The acid environment within the stomach leads to cleavage of the inactive precursor to pepsin and provides the low pH (<2.0) required for pepsin activity. Pepsin activity is significantly diminished at a pH of 4 and irreversibly inactivated and denatured at a pH of 7. Many of the secretagogues that stimulate acid secretion also stimulate pepsinogen release. The precise role of pepsin in the pathogenesis of PUD remains to be established.
Pathophysiologic Basis of Peptic Ulcer Disease
PUD encompasses both gastric and duodenal ulcers. Ulcers are defined as a break in the mucosal surface >5 mm in size, with depth to the submucosa. Duodenal (DU) and gastric ulcers (GU) share many common features in terms of pathogenesis, diagnosis, and treatment, but several factors distinguish them from one another.
DUs are estimated to occur in 6 to 15% of the western population. The incidence of DUs declined steadily from 1960 to 1980 and has remained stable since then. The death rates, need for surgery, and physician visits have decreased by >50% over the past 30 years. The reason for the reduction in the frequency of DUs is likely related to the decreasing frequency of Helicobacter pylori. Before the discovery of H. pylori, the natural history of DUs was typified by frequent recurrences after initial therapy. Eradication of H. pylori has greatly reduced these recurrence rates.
GUs tend to occur later in life than duodenal lesions, with a peak incidence reported in the sixth decade. More than half of GUs occur in males and are less common than DUs, perhaps due to the higher likelihood of GUs being silent and presenting only after a complication develops. Autopsy studies suggest a similar incidence of DUs and GUs.
DUs occur most often in the first portion of duodenum (>95%), with ~90% located within 3 cm of the pylorus. They are usually 1 cm in diameter but can occasionally reach 3 to 6 cm (giant ulcer). Ulcers are sharply demarcated, with depth at times reaching the muscularis propria. The base of the ulcer often consists of a zone of eosinophilic necrosis with surrounding fibrosis. Malignant duodenal ulcers are extremely rare.
In contrast to DUs, GUs can represent a malignancy. Benign GUs are most often found distal to the junction between the antrum and the acid secretory mucosa. This junction is variable, but in general the antral mucosa extends about two thirds of the distance of the lesser curvature and one third the way up the greater curvature. Benign GUs are quite rare in the gastric fundus and are histologically similar to DUs. Benign GUs associated with H. pylori are associated with antral gastritis. In contrast, NSAID-related GUs are not accompanied by chronic active gastritis but may instead have evidence of a chemical gastropathy.
It is now clear that H. pylori and NSAID-induced injury account for the majority of DUs. Gastric acid contributes to mucosal injury but does not play a primary role.
Many acid secretory abnormalities have been described in DU patients (Table 285-1). Of these, average basal and nocturnal gastric acid secretion appear to be increased in DU patients as compared to control; however, the level of overlap between DU patients and control subjects is substantial. The reason for this altered secretory process is unclear, but H. pylori infection may contribute to this finding. Accelerated gastric emptying of liquids has been noted in some DU patients but is not consistently observed; its role in DU formation, if any, is unclear. Bicarbonate secretion is significantly decreased in the duodenal bulb of patients with an active DU as compared to control subjects. H. pylori infection may also play a role in this process.
As in DUs, the majority of GUs can be attributed to either H. pylori or NSAID-induced mucosal damage. GUs that occur in the prepyloric area or those in the body associated with a DU or a duodenal scar are similar in pathogenesis to DUs. Gastric acid output (basal and stimulated) tends to be normal or decreased in GU patients. When GUs develop in the presence of minimal acid levels, impairment of mucosal defense factors may be present.
Abnormalities in resting and stimulated pyloric sphincter pressure with a concomitant increase in duodenal gastric reflux have been implicated in some GU patients. Although bile acids, lysolecithin, and pancreatic enzymes may injure gastric mucosa, a definite role for these in GU pathogenesis has not been established. Delayed gastric emptying of solids has been described in GU patients but has not been reported consistently. The observation that patients who have undergone disruption of the normal pyloric barrier (pyloroplasty, gastroenterostomy) often have superficial gastritis without frank ulceration decreases enthusiasm for duodenal gastric reflux as an explanation for GU pathogenesis.
H. pylori and acid peptic disorders
Gastric infection with the bacterium H. pylori accounts for the majority of PUD. This organism also plays a role in the development of gastric mucosal-associated lymphoid tissue (MALT) lymphoma and gastric adenocarcinoma. Although the entire genome of H. pylori has been sequenced, it is still not clear how this organism, which is in the stomach, causes ulceration in the duodenum, or whether its eradication will lead to a decrease in gastric cancer.
The bacterium, initially named Campylobacter pyloridis, is a gram-negative microaerophilic rod found most commonly in the deeper portions of the mucous gel coating the gastric mucosa or between the mucous layer and the gastric epithelium. It may attach to gastric epithelium but under normal circumstances does not appear to invade cells. It is strategically designed to live within the aggressive environment of the stomach. It is S-shaped (~0.5 × 3 m in size) and contains multiple sheathed flagella. Initially, H. pylori resides in the antrum but, over time, migrates towards the more proximal segments of the stomach. The organism is capable of transforming into a coccoid form, which represents a dormant state that may facilitate survival in adverse conditions. The bacterium expresses a host of factors that contribute to its ability to colonize the gastric mucosa and produce mucosal injury. Several of the key bacterial factors include urease (converting urea to NH3 and water, thus alkalinizing the surrounding acidic environment), catalase, lipase, adhesins, platelet-activating factor, cytotoxin-associated gene protein (Cag A), pic B (induces cytokines), and vacuolating cytotoxin (Vac A). Multiple strains of H. pylori exist and are characterized by their ability to express several of these factors (Cag A, Vac A, etc.). It is possible that the different diseases related to H. pylori infection can be attributed to different strains of the organism with distinct pathogenic features.
The prevalence of H. pylori varies throughout the world and depends to a great extent on the overall standard of living in the region. In developing parts of the world, 80% of the population may be infected by the age of 20. In contrast, in the United States, this organism is rare in childhood. The overall prevalence of H. pylori in the United States is ~30%, with individuals born before 1950 having a higher rate of infection than those born later. About 10% of Americans <30 are colonized with the bacteria. This rate of colonization increases with age, with about 50% of individuals age 50 being infected. Factors that predispose to higher colonization rates include poor socioeconomic status and less education. These factors, not race, are responsible for the rate of H. pylori infection in blacks and Hispanic Americans being double the rate seen in whites of comparable age. A summary of risk factors for H. pylori infection is shown in Table 285-2.
Transmission of H. pylori occurs from person to person, following an oral-oral or fecal-oral route. The risk of H. pylori infection is declining in developing countries. The rate of infection in the United States has fallen by >50% when compared to 30 years ago.
H. pylori infection is virtually always associated with a chronic active gastritis, but only 10 to 15% of infected individuals develop frank peptic ulceration. The basis for this difference is unknown. Initial studies suggested that >90% of all DUs were associated with H. pylori, but H. pylori is present in only 30 to 60% of individuals with DU and 70% of patients with GU. The pathophysiology of ulcers not associated with H. pylori or NSAID ingestion [or the rare Zollinger-Ellison syndrome (ZES)] is unclear.
The particular end result of H. pylori infection (gastritis, PUD, gastric MALT lymphoma, gastric cancer) is determined by a complex interplay between bacterial and host factors (Fig. 285-6).
Bacterial factors: H. pylori is able to facilitate gastric residence, induce mucosal injury, and avoid host defense. Different strains of H. pylori produce different virulence factors. A specific region of the bacterial genome, the pathogenicity island, encodes the virulence factors Cag A and pic B. Vac A also contributes to pathogenicity, though it is not encoded within the pathogenicity island. These virulence factors, in conjunction with additional bacterial constituents, can cause mucosal damage. Urease, which allows the bacteria to reside in the acidic stomach, generates NH3, which can damage epithelial cells. The bacteria produce surface factors that are chemotactic for neutrophils and monocytes, which in turn contribute to epithelial cell injury (see below). H. pylori makes proteases and phospholipases that break down the glycoprotein lipid complex of the mucous gel, thus reducing the efficacy of this first line of mucosal defense. H. pylori expresses adhesins, which facilitate attachment of the bacteria to gastric epithelial cells. Although lipopolysaccharide (LPS) of gram-negative bacteria often plays an important role in the infection, H. pylori LPS has low immunologic activity compared to that of other organisms. It may promote a smoldering chronic inflammation.
Host factors: The host responds to H. pylori infection by mounting an inflammatory response, which contributes to gastric epithelial cell damage without providing immunity against infection. The neutrophil response is strong both in acute and chronic infection. In addition, T lymphocytes and plasma cells are components of the chronic inflammatory infiltrate, supporting the involvement of antigen-specific cellular and humoral responses. A number of cytokines are released from both epithelial and immune modulatory cells in response to H. pylori infection including the proinflammatory cytokines tumor necrosis factor (TNF), interleukin (IL)1/, IL-6, interferon (IFN), and granulocyte-macrophage colony stimulating factor. Several chemokines such as IL-8 and growth-regulated oncogene (GRO) , involved in neutrophil recruitment/activation, and RANTES, which recruits mononuclear cells, have been observed in H. pylori-infected mucosa.
The reason for H. pylori-mediated duodenal ulceration remains unclear. One potential explanation is that gastric metaplasia in the duodenum of DU patients permits H. pylori to bind to it and produce local injury secondary to the host response. Another hypothesis is that H. pylori antral infection could lead to increased acid production, increased duodenal acid, and mucosal injury. Basal and stimulated [meal, gastrin-releasing peptide (GRP)] gastrin release are increased in H. pylori-infected individuals, and somatostatin-secreting D cells may be decreased. H. pylori infection might induce increased acid secretion through both direct and indirect actions of H. pylori and proinflammatory cytokines (IL-8, TNF, and IL-1) on G, D, and parietal cells (Fig. 285-7). H. pylori infection has also been associated with decreased duodenal mucosal bicarbonate production. Data supporting and contradicting each of these interesting theories have been demonstrated. Thus, the mechanism by which H pylori infection of the stomach leads to duodenal ulceration remains to be established.
NSAIDs represent one of the most commonly used medications in the United States. More than 30 billion over-the-counter tablets and 70 million prescriptions are sold yearly in the United States alone. The spectrum of NSAID-induced morbidity ranges from nausea and dyspepsia (prevalence reported as high as 50 to 60%) to a serious gastrointestinal complication such as frank peptic ulceration complicated by bleeding or perforation in as many as 3 to 4% of users per year. About 20,000 patients die each year from serious gastrointestinal complications from NSAIDs. Unfortunately, dyspeptic symptoms do not correlate with NSAID-induced pathology. Over 80% of patients with serious NSAID-related complications did not have preceding dyspepsia. In view of the lack of warning signs, it is important to identify patients who are at increased risk for morbidity and mortality related to NSAID usage. A summary of established and possible risk factors is presented in Table 285-3.
Prostaglandins play a critical role in maintaining gastroduodenal mucosal integrity and repair. It therefore follows that interruption of prostaglandin synthesis can impair mucosal defense and repair, thus facilitating mucosal injury via a systemic mechanism. A summary of the pathogenetic pathways by which systemically administered NSAIDs may lead to mucosal injury is shown in Fig. 285-8.
Injury to the mucosa also occurs as a result of the topical encounter with NSAIDs. Aspirin and many NSAIDs are weak acids that remain in a nonionized lipophilic form when found within the acid environment of the stomach. Under these conditions, NSAIDs migrate across lipid membranes of epithelial cells, leading to cell injury once trapped intracellularly in an ionized form. Topical NSAIDs can also alter the surface mucous layer, permitting back diffusion of H+ and pepsin, leading to further epithelial cell damage.
Miscellaneous Pathogenetic Factors in Acid Peptic Disease
Cigarette smoking has been implicated in the pathogenesis of PUD. Not only have smokers been found to have ulcers more frequently than do nonsmokers, but smoking appears to decrease healing rates, impair response to therapy, and increase ulcer-related complications such as perforation. The mechanism responsible for increased ulcer diathesis in smokers is unknown. Theories have included altered gastric emptying, decreased proximal duodenal bicarbonate production, and cigarette-induced generation of noxious mucosal free radicals. Acid secretion is not abnormal in smokers. Despite these interesting theories, a unifying mechanism for cigarette-induced peptic ulcer diathesis has not been established.
Genetic predisposition has also been considered to play a role in ulcer development. First-degree relatives of DU patients are three times as likely to develop an ulcer; however, the potential role of H. pylori infection in contacts is a major consideration. Increased frequency of blood group O and of the nonsecretor status have also been implicated as genetic risk factors for peptic diathesis. However, H. pylori preferentially binds to group O antigens. Therefore, the role of genetic predisposition in common PUD has not been established.
Psychological stress has been thought to contribute to PUD, but studies examining the role of psychological factors in its pathogenesis have generated conflicting results. Although PUD is associated with certain personality traits (neuroticism), these same traits are also present in individuals with nonulcer dyspepsia (NUD) and other functional and organic disorders. Although more work in this area is needed, no typical PUD personality has been found.
Diet has also been thought to play a role in peptic diseases. Certain foods can cause dyspepsia, but no convincing studies indicate an association between ulcer formation and a specific diet. This is also true for beverages containing alcohol and caffeine. Specific chronic disorders have been associated with PUD (Table 285-4).
Multiple factors play a role in the pathogenesis of PUD. The two predominant causes are H. pylori infection and NSAID ingestion. PUD not related to H. pylori or NSAIDs may be increasing. Independent of the inciting or injurious agent, peptic ulcers develop as a result of an imbalance between mucosal protection/repair and aggressive factors. Gastric acid plays an essential role in mucosal injury.
Abdominal pain is common to many gastrointestinal disorders, including DU and GU, but has a poor predictive value for the presence of either DU or GU. Up to 10% of patients with NSAID-induced mucosal disease can present with a complication (bleeding, perforation, and obstruction) without antecedent symptoms. Despite this poor correlation, a careful history and physical examination are essential components of the approach to a patient suspected of having peptic ulcers.
Epigastric pain described as a burning or gnawing discomfort can be present in both DU and GU. The discomfort is also described as an ill-defined, aching sensation or as hunger pain. The typical pain pattern in DU occurs 90 min to 3 h after a meal and is frequently relieved by antacids or food. Pain that awakes the patient from sleep (between midnight and 3 A.M.) is the most discriminating symptom, with two-thirds of DU patients describing this complaint. Unfortunately, this symptom is also present in one-third of patients with NUD. The pain pattern in GU patients may be different from that in DU patients, where discomfort may actually be precipitated by food. Nausea and weight loss occur more commonly in GU patients. In the United States, endoscopy detects ulcers in <30% of patients who have dyspepsia. Despite this, 40% of these individuals with typical ulcer symptoms had an ulcer crater, and 40% had gastroduodenitis on endoscopic examination.
The mechanism for development of abdominal pain in ulcer patients is unknown. Several possible explanations include acid-induced activation of chemical receptors in the duodenum, enhanced duodenal sensitivity to bile acids and pepsin, or altered gastroduodenal motility.
Variation in the intensity or distribution of the abdominal pain, as well as the onset of associated symptoms such as nausea and/or vomiting, may be indicative of an ulcer complication. Dyspepsia that becomes constant, is no longer relieved by food or antacids, or radiates to the back may indicate a penetrating ulcer (pancreas). Sudden onset of severe, generalized abdominal pain may indicate perforation. Pain worsening with meals, nausea, and vomiting of undigested food suggest gastric outlet obstruction. Tarry stools or coffee ground emesis indicate bleeding.
Epigastric tenderness is the most frequent finding in patients with GU or DU. Pain may be found to the right of the midline in 20% of patients. Unfortunately, the predictive value of this finding is rather low. Physical examination is critically important for discovering evidence of ulcer complication. Tachycardia and orthostasis suggest dehydration secondary to vomiting or active gastrointestinal blood loss. A severely tender, boardlike abdomen suggests a perforation. Presence of a succussion splash indicates retained fluid in the stomach, suggesting gastric outlet obstruction.
Gastrointestinal bleeding is the most common complication observed in PUD. It occurs in ~15% of patients and more often in individuals >60 years old. The higher incidence in the elderly is likely due to the increased use of NSAIDs in this group. As many as 20% of patients with ulcer-related hemorrhage bleed without any preceding warning signs or symptoms.
The second most common ulcer-related complication is perforation, being reported in as many as 6 to 7% of PUD patients. As in the case of bleeding, the incidence of perforation in the elderly appears to be increasing secondary to increased use of NSAIDs. Penetration is a form of perforation in which the ulcer bed tunnels into an adjacent organ. DUs tend to penetrate posteriorly into the pancreas, leading to pancreatitis, whereas GUs tend to penetrate into the left hepatic lobe. Gastrocolic fistulas associated with GUs have also been described.
Gastric Outlet Obstruction
Gastric outlet obstruction is the least common ulcer-related complication, occurring in 1 to 2% of patients. A patient may have relative obstruction secondary to ulcer-related inflammation and edema in the peripyloric region. This process often resolves with ulcer healing. A fixed, mechanical obstruction secondary to scar formation in the peripyloric areas is also possible. The latter requires endoscopic (balloon dilation) or surgical intervention. Signs and symptoms relative to mechanical obstruction may develop insidiously. New onset of early satiety, nausea, vomiting, increase of postprandial abdominal pain, and weight loss should make gastric outlet obstruction a possible diagnosis.
The list of gastrointestinal and nongastrointestinal disorders that can mimic ulceration of the stomach or duodenum is quite extensive. The most commonly encountered diagnosis among patients seen for upper abdominal discomfort is NUD. NUD, also known as functional dyspepsia or essential dyspepsia, refers to a group of heterogeneous disorders typified by upper abdominal pain without the presence of an ulcer. Dyspepsia has been reported to occur in up to 30% of the U.S. population. Up to 60% of patients seeking medical care for dyspepsia have a negative diagnostic evaluation. The etiology of NUD is not established, and the potential role of H. pylori in NUD remains controversial.
Several additional disease processes that may present with "ulcer-like" symptoms include proximal gastrointestinal tumors, gastroesophageal reflux, vascular disease, pancreaticobiliary disease (biliary colic, chronic pancreatitis), and gastroduodenal Crohn's disease.
In view of the poor predictive value of abdominal pain for the presence of a gastroduodenal ulcer and the multiple disease processes that can mimic this disease, the clinician is often confronted with having to establish the presence of an ulcer. Documentation of an ulcer requires either a radiographic (barium study) or an endoscopic procedure.
Barium studies of the proximal gastrointestinal tract are still commonly used as a first test for documenting an ulcer. The sensitivity of older single-contrast barium meals for detecting a DU is as high as 80%, with a double-contrast study providing detection rates as high as 90%. Sensitivity for detection is decreased in small ulcers (<0.5 cm), presence of previous scarring, or in postoperative patients. A DU appears as a well-demarcated crater, most often seen in the bulb. A GU may represent benign or malignant disease. Typically, a benign GU also appears as a discrete crater with radiating mucosal folds originating from the ulcer margin. Ulcers >3 cm in size or those associated with a mass are more often malignant. Unfortunately, up to 8% of GUs that appear to be benign by radiographic appearance are malignant by endoscopy or surgery. Radiographic studies that show a GU must be followed by endoscopy and biopsy.
Endoscopy provides the most sensitive and specific approach for examining the upper gastrointestinal tract. In addition to permitting direct visualization of the mucosa, endoscopy facilitates photographic documentation of a mucosal defect and tissue biopsy to rule out malignancy (GU) or H. pylori. Endoscopic examination is particularly helpful in identifying lesions too small to detect by radiographic examination, for evaluation of atypical radiographic abnormalities, or to determine if an ulcer is a source of blood loss.
Although the methods for diagnosing H. pylori are outlined in Chap. 154, a brief summary will be included here (Table 285-5). PyloriTek, a biopsy urease test, has a sensitivity and specificity of >90 to 95%. In the interest of making a diagnosis of H. pylori without the need for performing endoscopy, several noninvasive methods for detecting this organism have been developed. Three types of studies routinely used include serologic testing, the 13C- or 14C-urea breath test, and the fecal H. pylori antigen test.
Occasionally, specialized testing such as serum gastrin and gastric acid analysis or sham feeding may be needed in individuals with complicated or refractory PUD (see "Zollinger-Ellison Syndrome," below). Screening for aspirin or NSAIDS (blood or urine) may also be necessary in refractory, H. pylori-negative PUD patients.
Before the discovery of H. pylori, the therapy of PUD disease was centered on the old dictum by Schwartz of "no acid, no ulcer." Although acid secretion is still important in the pathogenesis of PUD, eradication of H. pylori and therapy/prevention of NSAID-induced disease is the mainstay. A summary of commonly used drugs for treatment of acid peptic disorders is shown in Table 285-6.
Acid Neutralizing/Inhibitory Drugs
Before we understood the important role of histamine in stimulating parietal cell activity, neutralization of secreted acid with antacids constituted the main form of therapy for peptic ulcers. They are now rarely, if ever, used as the primary therapeutic agent but instead are often used by patients for symptomatic relief of dyspepsia. The most commonly used agents are mixtures of aluminum hydroxide and magnesium hydroxide. Aluminum hydroxide can produce constipation and phosphate depletion; magnesium hydroxide may cause loose stools. Many of the commonly used antacids (e.g., Maalox, Mylanta) have a combination of both aluminum and magnesium hydroxide in order to avoid these side effects. The magnesium-containing preparation should not be used in chronic renal failure patients because of possible hypermagnesemia, and aluminum may cause chronic neurotoxicity in these patients.
Calcium carbonate and sodium bicarbonate are potent antacids with varying levels of potential problems. The long-term use of calcium carbonate (converts to calcium chloride in the stomach) can lead to milk-alkali syndrome (hypercalcemia, hyperphosphatemia with possible renal calcinosis and progression to renal insufficiency). Sodium bicarbonate may induce systemic alkalosis.
H2 Receptor antagonists
Four of these agents are presently available (cimetidine, ranitidine, famotidine, and nizatidine), and their structures share homology with histamine (Fig. 285-9). Although each has different potency, all will significantly inhibit basal and stimulated acid secretion to comparable levels when used at therapeutic doses. Moreover, similar ulcer-healing rates are achieved with each drug when used at the correct dosage. Presently, this class of drug is often used for treatment of active ulcers (4 to 6 weeks) in combination with antibiotics directed at eradicating H. pylori (see below).
Cimetidine was the first H2 receptor antagonist used for the treatment of acid peptic disorders. The initial recommended dosing profile for cimetidine was 300 mg four times per day. Subsequent studies have documented the efficacy of using 800 mg at bedtime for treatment of active ulcer, with healing rates approaching 80% at 4 weeks. Cimetidine may have weak antiandrogenic side effects resulting in reversible gynecomastia and impotence, primarily in patients receiving high doses for prolonged periods of time (months to years, as in ZES). In view of cimetidine's ability to inhibit cytochrome P450, careful monitoring of drugs such as warfarin, phenytoin, and theophylline is indicated with long-term usage. Other rare reversible adverse effects reported with cimetidine include confusion and elevated levels of serum aminotransferases, creatinine, and serum prolactin. Ranitidine, famotidine, and nizatidine are more potent H2 receptor antagonists than cimetidine. Each can be used once a day at bedtime. Comparable nighttime dosing regimens are ranitidine, 300 mg, famotidine, 40 mg, and nizatidine, 300 mg.
Additional rare, reversible systemic toxicities reported with H2 receptor antagonists include pancytopenia, neutropenia, anemia, and thrombocytopenia, with a prevalence rate varying from 0.01 to 0.2%. Cimetidine and rantidine (to a lesser extent) can bind to hepatic cytochrome P450, whereas the newer agents, famotidine and nizatidine, do not.
Proton pump (H+,K+-ATPase) inhibitors
Omeprazole, lansoprazole, and the newest additions, rabeprazole and pantoprazole, are substituted benzimidazole derivatives that covalently bind and irreversibly inhibit H+,K+-ATPase. These are the most potent acid inhibitory agents available. Omeprazole and lansoprazole are the proton pump inhibitors (PPIs) that have been used for the longest time. Both are acid labile and are administered as enteric-coated granules in a sustained-release capsule that dissolves within the small intestine at a pH of 6. These agents are lipophilic compounds; upon entering the parietal cell, they are protonated and trapped within the acid environment of the tubulovesicular and canalicular system. These agents potently inhibit all phases of gastric acid secretion. Onset of action is rapid, with a maximum acid inhibitory effect between 2 and 6 h after administration and duration of inhibition lasting up to 72 to 96 h. With repeated daily dosing, progressive acid inhibitory effects are observed, with basal and secretagogue-stimulated acid production being inhibited by >95% after 1 week of therapy. The half-life of PPIs is approximately 18 h, thus it can take between 2 and 5 days for gastric acid secretion to return to normal levels once these drugs have been discontinued. Because the pumps need to be activated for these agents to be effective, their efficacy is maximized if they are administered before a meal (e.g., in the morning before breakfast). Standard dosing for omeprazole and lansoprazole is 20 mg and 30 mg once per day, respectively. Mild to moderate hypergastrinemia has been observed in patients taking these drugs. Carcinoid tumors developed in some animals given the drugs preclinically; however, extensive experience has failed to demonstrate gastric carcinoid tumor development in humans. Serum gastrin levels return to normal levels within 1 to 2 weeks after drug cessation. As with any agent that leads to significant hypochlorhydria, PPIs may interfere with absorption of drugs such as ketoconazole, ampicillin, iron, and digoxin. Hepatic cytochrome P450 can be inhibited by these agents, but the overall clinical significance of this observation is not definitely established. Caution should be taken when using warfarin, diazepam, and phenytoin concomitantly with PPIs.
Sucralfate is a complex sucrose salt in which the hydroxyl groups have been substituted by aluminum hydroxide and sulfate. This compound is insoluble in water and becomes a viscous paste within the stomach and duodenum, binding primarily to sites of active ulceration. Sucralfate may act by several mechanisms. In the gastric environment, aluminum hydroxide dissociates, leaving the polar sulfate anion, which can bind to positively charged tissue proteins found within the ulcer bed, and providing a physicochemical barrier impeding further tissue injury by acid and pepsin. Sucralfate may also induce a trophic effect by binding growth factors such as EGF, enhance prostaglandin synthesis, stimulate mucous and bicarbonate secretion, and enhance mucosal defense and repair. Toxicity from this drug is rare, with constipation being the most common one reported (2 to 3%). It should be avoided in patients with chronic renal insufficiency to prevent aluminum-induced neurotoxicity. Hypophosphatemia and gastric bezoar formation have also been rarely reported. Standard dosing of sucralfate is 1 g four times per day.
Sir William Osler considered bismuth-containing compounds the drug of choice for treating PUD. The resurgence in the use of these agents is due to their effect against H. pylori. Colloidal bismuth subcitrate (CBS) and bismuth subsalicylate (BSS, Pepto-Bismol) are the most widely used preparations. The mechanism by which these agents induce ulcer healing is unclear. Potential mechanisms include ulcer coating; prevention of further pepsin/HCl-induced damage; binding of pepsin; and stimulation of prostaglandins, bicarbonate, and mucous secretion. Adverse effects with short-term usage are rare with bismuth compounds. Long-term usage with high doses, especially with the avidly absorbed CBS, may lead to neurotoxicity. These compounds are commonly used as one of the agents in an anti-H. pylori regimen (see below).
In view of their central role in maintaining mucosal integrity and repair, stable prostaglandin analogues were developed for the treatment of PUD. The prostaglandin E1 derivative misoprostal is the only agent of this class approved by the U.S. Food and Drug Administration for clinical use in the prevention of NSAID-induced gastroduodenal mucosal injury (see below). The mechanism by which this rapidly absorbed drug provides its therapeutic effect is through enhancement of mucosal defense and repair. Prostaglandin analogues enhance mucous bicarbonate secretion, stimulate mucosal blood flow, and decrease mucosal cell turnover. The most common toxicity noted with this drug is diarrhea (10 to 30% incidence). Other major toxicities include uterine bleeding and contractions; misoprostal is contraindicated in women who may be pregnant, and women of childbearing age must be made clearly aware of this potential drug toxicity. The standard therapeutic dose is 200 g four times per day.
A number of drugs aimed at treating acid peptic disorders have been developed over the years. In view of their limited utilization in the United States, if any, they will only be listed briefly. Anticholinergics, designed to inhibit activation of the muscarinic receptor in parietal cells, met with limited success due to their relatively weak acid-inhibiting effect and significant side effects (dry eyes, dry mouth, urinary retention). Tricyclic antidepressants have been suggested by some, but again the toxicity of these agents in comparison to the safe, effective drugs already described, precludes their utility. Finally, the licorice extract carbenoxolone has aldosterone-like side effects with fluid retention and hypokalemia, making it an undesirable therapeutic option.
Therapy of H. pylori
Extensive effort has been placed into determining who of the many individuals with H. pylori infection should be treated. The common conclusion arrived at by multiple consensus conferences (National Institutes of Health Consensus Development, American Digestive Health Foundation International Update Conference, European Maastricht Consensus, and Asia Pacific Consensus Conference) is that H. pylori should be eradicated in patients with documented PUD. This holds true independent of time of presentation (first episode or not), severity of symptoms, presence of confounding factors such as ingestion of NSAIDs, or whether the ulcer is in remission. Some have advocated treating patients with a history of documented PUD who are found to be H. pylori-positive by serology or breath testing. Over half of patients with gastric MALT lymphoma experience complete remission of the tumor in response to H. pylori eradication. Treating patients with NUD or to prevent gastric cancer remains controversial.
Multiple drugs have been evaluated in the therapy of H. pylori. No single agent is effective in eradicating the organism. Combination therapy for 14 days provides the greatest efficacy. A short-time course administration (7 to 10 days), although attractive, has not proven as successful as the 14-day regimens. The agents used with the greatest frequency include amoxicillin, metronidazole, tetracycline, clarithromycin, and bismuth compounds.
The physician's goal in treating PUD is to provide relief of symptoms (pain or dyspepsia), promote ulcer healing, and ultimately prevent ulcer recurrence and complications. The greatest impact of understanding the role of H. pylori in peptic disease has been the ability to prevent recurrence of what was often a recurring disease. Documented eradication of H. pylori in patients with PUD is associated with a dramatic decrease in ulcer recurrence to 4% (as compared to 59%) in GU patients and 6% (compared to 67%) in DU patients. Eradication of the organism may lead to diminished recurrent ulcer bleeding. The impact of its eradication on ulcer perforation is unclear.
Suggested treatment regimens for H. pylori are outlined in Table 285-7. Choice of a particular regimen will be influenced by several factors including efficacy, patient tolerance, existing antibiotic resistance, and cost of the drugs. The aim for initial eradication rates should be 85 to 90%. Dual therapy [PPI plus amoxicillin, PPI plus clarithromycin, ranitidine bismuth citrate (Tritec) plus clarithromycin] are not recommended in view of studies demonstrating eradication rates of <80 to 85%. The combination of bismuth, metronidazole, and tetracycline was the first triple regimen found effective against H. pylori. The combination of two antibiotics plus either a PPI, H2 blocker, or bismuth compound has comparable success rates. Addition of acid suppression assists in providing early symptom relief and may enhance bacterial eradication.
Triple therapy, although effective, has several drawbacks, including the potential for poor patient compliance and drug-induced side effects. Compliance is being addressed somewhat by simplifying the regimens so that patients can take the medications twice a day. Simpler (dual therapy) and shorter regimens (7 and 10 days) are not as effective as triple therapy for 14 days. Two anti-H. pylori regimens are available in prepackaged formulation: Prevpac (lansoprazole, clarithromycin, and amoxicillin) and Helidac (bismuth subsalicylate, tetracycline, and metronidazole). The contents of the Prevpac are to be taken twice per day for 14 days, whereas Helidac constituents are taken four times per day with an antisecretory agent (PPI or H2 blocker), also taken for at least 14 days.
Side effects have been reported in up to 20 to 30% of patients on triple therapy. Bismuth may cause black stools, constipation, or darkening of the tongue. The most feared complication with amoxicillin is pseudomembranous colitis, but this occurs in <1 to 2% of patients. Amoxicillin can also lead to antibiotic-associated diarrhea, nausea, vomiting, skin rash, and allergic reaction. Tetracycline has been reported to cause rashes and very rarely hepatotoxicity and anaphylaxis.
One important concern with treating patients who may not need treatment is the potential for development of antibiotic-resistant strains. The incidence and type of antibiotic-resistant H. pylori strains vary worldwide. Strains resistant to metronidazole, clarithromycin, amoxicillin, and tetracycline have been described, with the latter two being uncommon. Antibiotic-resistant strains are the most common cause for treatment failure in compliant patients. Unfortunately, in vitro resistance does not predict outcome in patients. Culture and sensitivity testing of H. pylori is not performed routinely. Although resistance to metronidazole has been found in as many as 30% and 95% of isolates in North America and Asia, respectively, triple therapy is effective in eradicating the organism in >50% of patients infected with a resistant strain.
Failure of H. pylori eradication with triple therapy is usually due to infection with a resistant organism. Quadruple therapy (Table 285-7) where clarithromycin is substituted for metronidazole (or vice versa) should be the next step. If eradication is still not achieved in a compliant patient, then culture and sensitivity of the organism should be considered.
Reinfection after successful eradication of H. pylori is rare in the United States (<1%/year). If recurrent infection occurs within the first 6 months after completing therapy, the most likely explanation is recrudescence as opposed to reinfection, which occurs later in time.
Therapy of NSAID-Related Gastric or Duodenal Injury
Medical intervention for NSAID-related mucosal injury includes treatment of an active ulcer and prevention of future injury. Recommendations for the treatment and prevention of NSAID-related mucosal injury are in Table 285-8. Ideally the injurious agent should be stopped as the first step in the therapy of an active NSAID-induced ulcer. If that is possible, then treatment with one of the acid inhibitory agents (H2 blockers, PPIs) is indicated. Cessation of NSAIDs is not always possible because of the patient's severe underlying disease. Only PPIs can heal GUs or DUs, independent of whether NSAIDs are discontinued.
Prevention of NSAID-induced ulceration can be accomplished by misoprostol (200 g qid) or a PPI. High-dose H2 blockers (famotidine, 40 mg bid) have also shown some promise. The use of COX-2-selective NSAIDs may also reduce injury to gastric mucosa. Two highly selective COX-2 inhibitors, celecoxib and rofecoxib, are 100 times more selective inhibitors of COX-2 than standard NSAIDs, leading to gastric or duodenal mucosal injury that is comparable to placebo. However, evaluation of possible drug toxicities, such as altered renal function and induction of thrombosis, requires more data.
Approach and Therapy: Summary
Controversy continues regarding the best approach to the patient who presents with dyspepsia (Chap. 41). The discovery of H. pylori and its role in pathogenesis of ulcers has added a new variable to the equation. Previously, if a patient <50 presented with dyspepsia and without alarming signs or symptoms suggestive of an ulcer complication or malignancy, an empirical therapeutic trial with acid suppression was commonly recommended. Although this approach is practiced by some today, an approach presently gaining approval for the treatment of patients with dyspepsia is outlined in Fig. 285-10. The referral to a gastroenterologist is for the potential need of endoscopy and subsequent evaluation and treatment if the endoscopy is negative.
Once an ulcer (GU or DU) is documented, then the main issue at stake is whether H. pylori or an NSAID is involved. With H. pylori present, independent of the NSAID status, triple therapy is recommended for 14 days, followed by continued acid-suppressing drugs (H2 receptor antagonist or PPIs) for a total of 4 to 6 weeks. Selection of patients for documentation of H. pylori eradication is an area of some debate. The test of choice for documenting eradication is the urea breath test (UBT). The stool antigen study may also hold promise for this purpose and should certainly be performed if UBT is not available. Serologic testing is not useful for the purpose of documenting eradication since antibody titers fall slowly and often do not become undetectable. Two approaches toward documentation of eradication exist: (1) test for eradication only in individuals with a complicated course or in individuals who are frail or with multisystem disease who would do poorly with an ulcer recurrence, and (2) test all patients for successful eradication. Some recommend that patients with complicated ulcer disease or who are frail should be treated with long-term acid suppression, thus making documentation of H. pylori eradication a moot point. In view of this discrepancy in practice, it would be best to discuss with the patient the different options available.
Several issues differentiate the approach to a GU versus a DU. GUs, especially of the body and fundus, have the potential of being malignant. Multiple biopsies of a GU should be taken initially; even if these are negative for neoplasm, repeat endoscopy to document healing at 8 to 12 weeks should be performed, with biopsy if the ulcer is still present. About 70% of GUs eventually found to be malignant undergo significant (usually incomplete) healing.
The majority (>90%) of GUs and DUs heal with the conventional therapy outlined above. A GU that fails to heal after 12 weeks and a DU that doesn't heal after 8 weeks of therapy should be considered refractory. Once poor compliance and persistent H. pylori infection have been excluded, NSAID use, either inadvertent or surreptitious, must be excluded. In addition, cigarette smoking must be eliminated. For a GU, malignancy must be meticulously excluded. Next, consideration should be given to a gastric hypersecretory state, which can be excluded with gastric acid analysis. Although a subset of patients have gastric acid hypersecretion of unclear etiology as a contributing factor to refractory ulcers, ZES should be excluded with a fasting gastrin or secretin stimulation test (see below). More than 90% of refractory ulcers (either DUs or GUs) heal after 8 weeks of treatment with higher doses of PPI (omeprazole, 40 mg/d). This higher dose is also effective in maintaining remission. Surgical intervention may be a consideration at this point; however, other rare causes of refractory ulcers must be excluded before recommending surgery. Rare etiologies of refractory ulcers that may be diagnosed by gastric or duodenal biopsies include: ischemia, Crohn's disease, amyloidosis, sarcoidosis, lymphoma, eosinophilic gastroenteritis, or infection [cytomegalovirus (CMV), tuberculosis, or syphilis].
Surgical intervention in PUD can be viewed as being either elective, for treatment of medically refractory disease, or as urgent/emergent, for the treatment of an ulcer-related complication. Refractory ulcers are an exceedingly rare occurrence. Surgery is more often required for treatment of an ulcer-related complication. Gastrointestinal bleeding (Chap. 44), perforation, and gastric outlet obstruction are the three complications that may require surgical intervention.
Hemorrhage is the most common ulcer-related complication, occurring in ~15 to 25% of patients. Bleeding may occur in any age group but is most often seen in older patients (sixth decade or beyond). The majority of patients stop bleeding spontaneously, but in some, endoscopic therapy (Chap. 283) is necessary. Patients unresponsive or refractory to endoscopic intervention will require surgery (~5% of transfusion-requiring patients).
Free peritoneal perforation occurs in ~2 to 3% of DU patients. As in the case of bleeding, up to 10% of these patients will not have antecedent ulcer symptoms. Concomitant bleeding may occur in up to 10% of patients with perforation, with mortality being increased substantially. Peptic ulcer can also penetrate into adjacent organs, especially with a posterior DU, which can penetrate into the pancreas, colon, liver, or biliary tree.
Pyloric channel ulcers or DUs can lead to gastric outlet obstruction in ~2 to 3% of patients. This can result from chronic scarring or from impaired motility due to inflammation and/or edema with pylorospasm. Patients may present with early satiety, nausea, vomiting of undigested food, and weight loss. Conservative management with nasogastric suction, intravenous hydration/nutrition, and antisecretory agents is indicated for 7 to 10 days with the hope that a functional obstruction will reverse. If a mechanical obstruction persists, endoscopic intervention with balloon dilation may be effective. Surgery should be considered if all else fails.
Specific Operations for Duodenal Ulcers
Surgical treatment is designed to decrease gastric acid secretion. Operations most commonly performed include vagotomy and drainage (by pyloroplasty, gastroduodenostomy, or gastrojejunostomy), highly selective vagotomy (which does not require a drainage procedure), and vagotomy with antrectomy. The specific procedure performed is dictated by the underlying circumstances: elective vs. emergency, the degree and extent of duodenal ulceration, and the expertise of the surgeon.
Vagotomy is a component of each of these procedures and is aimed at decreasing acid secretion through ablating cholinergic input to the stomach. Unfortunately, both truncal and selective vagotomy (preserves the celiac and hepatic branches) result in gastric atony despite successful reduction of both basal acid output (BAO, decreased by 85%) and maximal acid output (MAO, decreased by 50%). Drainage procedure through pyloroplasty or gastroduodenostomy is required in an effort to compensate for the vagotomy-induced gastric motility disorder. To minimize gastric dysmotility, highly selective vagotomy (also known as parietal cell, super selective, and proximal vagotomy) was developed. Only the vagal fibers innervating the portion of the stomach that contains parietal cells is transected, thus leaving fibers important for regulating gastric motility intact. Although this procedure leads to an immediate decrease in both BAO and stimulated acid output, acid secretion recovers over time. By the end of the first postoperative year, basal and stimulated acid output are ~30 and 50%, respectively, of preoperative levels. Ulcer recurrence rates are higher with highly selective vagotomy, although the overall complication rates are lower (Table 285-9).
The procedure that provides the lowest rates of ulcer recurrence but has the highest complication rate is vagotomy (truncal or selective) in combination with antrectomy. Antrectomy is aimed at eliminating an additional stimulant of gastric acid secretion, gastrin. Gastrin originates from G cells found in the antrum. Two principal types of reanastomoses are used after antrectomy, gastroduodenostomy (Billroth I) or gastrojejunostomy (Billroth II) (Fig. 285-11). Although Billroth I is often preferred over II, severe duodenal inflammation or scarring may preclude its performance.
Of these procedures, highly selective vagotomy may be the one of choice in the elective setting, except in situations where ulcer recurrence rates are high (prepyloric ulcers and those refractory to H2 therapy). Selection of vagotomy and antrectomy may be more appropriate in these circumstances.
These procedures have been traditionally performed by standard laparotomy. The advent of laparoscopic surgery has led several surgical teams to successfully perform highly selective vagotomy, truncal vagotomy/pyloroplasty, and truncal vagotomy/antrectomy through this approach. An increase in the number of laparoscopic procedures for treatment of PUD is expected.
Specific Operations for Gastric Ulcers
The location and the presence of a concomitant DU dictate the operative procedure performed for a GU. Antrectomy (including the ulcer) with a Billroth I anastomosis is the treatment of choice for an antral ulcer. Vagotomy is performed only if a DU is present. Although ulcer excision with vagotomy and drainage procedure has been proposed, the higher incidence of ulcer recurrence makes this a less desirable approach. Ulcers located near the esophagogastric junction may require a more radical approach, a subtotal gastrectomy with a Roux-en-Y esophagogastrojejunostomy (Csende's procedure). A less aggressive approach including antrectomy, intraoperative ulcer biopsy, and vagotomy (Kelling-Madlener procedure) may be indicated in fragile patients with a high GU. Ulcer recurrence approaches 30% with this procedure.
Complications seen after surgery for PUD are related primarily to the extent of the anatomical modification performed. Minimal alteration (highly selective vagotomy) is associated with higher rates of ulcer recurrence and less gastrointestinal disturbance. More aggressive surgical procedures have a lower rate of ulcer recurrence but a greater incidence of gastrointestinal dysfunction. Overall, morbidity and mortality related to these procedures are quite low. Morbidity associated with vagotomy and antrectomy or pyloroplasty is 5%, with mortality ~1%. Highly selective vagotomy has lower morbidity and mortality rates of 1 and 0.3%, respectively.
In addition to the potential early consequences of any intraabdominal procedure (bleeding, infection, thromboembolism), gastroparesis, duodenal stump leak, and efferent loop obstruction can be observed.
The risk of ulcer recurrence is directly related to the procedure performed (Table 285-9). Ulcers that recur after partial gastric resection tend to develop at the anastomosis (stomal or marginal ulcer). Epigastric abdominal pain is the most frequent presenting complaint. Severity and duration of pain tend to be more progressive than observed with DUs before surgery.
Ulcers may recur for several reasons including incomplete vagotomy, retained antrum, and, less likely, persistent or recurrent H. pylori infection. ZES should have been excluded preoperatively. More recently, surreptitious use of NSAIDs has been found to be a reason for recurrent ulcers after surgery, especially if the initial procedure was done for an NSAID-induced ulcer. Once H. pylori and NSAIDs have been excluded as etiologic factors, the question of incomplete vagotomy or retained gastric antrum should be explored. For the latter, fasting plasma gastrin levels should be determined. If elevated, retained antrum or ZES (see below) should be considered. A combination of acid secretory analysis and secretin stimulation (see below) can assist in this differential diagnosis. Incomplete vagotomy can be ruled out by gastric acid analysis coupled with sham feeding. In this test, gastric acid output is measured while the patient sees, smells, and chews a meal (without swallowing). The cephalic phase of gastric secretion, which is mediated by the vagus, is being assessed with this study. An increase in gastric acid output in response to sham feeding is evidence that the vagus nerve is intact.
Medical therapy with H2 blockers will heal postoperative ulceration in 70 to 90% of patients. The efficacy of PPIs has not been fully assessed in this group, but one may anticipate greater rates of ulcer healing compared to those obtained with H2 blockers. Repeat operation (complete vagotomy, partial gastrectomy) may be required in a small subgroup of patients who have not responded to aggressive medical management.
Afferent Loop Syndromes
Two types of afferent loop syndrome can occur in patients who have undergone partial gastric resection with Billroth II anastomosis. The most common of the two is bacterial overgrowth in the afferent limb secondary to stasis. Patients may experience postprandial abdominal pain, bloating, and diarrhea with concomitant malabsorption of fats and vitamin B12. Cases refractory to antibiotics may require surgical revision of the loop. The less common afferent loop syndrome can present with severe abdominal pain and bloating that occur 20 to 60 min after meals. Pain is often followed by nausea and vomiting of bile-containing material. The pain and bloating may improve after emesis. The cause of this clinical picture is theorized to be incomplete drainage of bile and pancreatic secretions from an afferent loop that is partially obstructed. Cases refractory to dietary measures may need surgical revision.
Dumping syndrome consists of a series of vasomotor and gastrointestinal signs and symptoms and occurs in patients who have undergone vagotomy and drainage (especially Billroth procedures). Two phases of dumping, early and late, can occur. Early dumping takes place 15 to 30 min after meals and consists of crampy abdominal discomfort, nausea, diarrhea, belching, tachycardia, palpitations, diaphoresis, light-headedness, and, rarely, syncope. These signs and symptoms arise from the rapid emptying of hyperosmolar gastric contents into the small intestine, resulting in a fluid shift into the gut lumen with plasma volume contraction and acute intestinal distention. Release of vasoactive gastrointestinal hormones (vasoactive intestinal polypeptide, neurotensin, motilin) is also theorized to play a role in early dumping.
The late phase of dumping typically occurs 90 min to 3 h after meals. Vasomotor symptoms (light-headedness, diaphoresis, palpitations, tachycardia, and syncope) predominate during this phase. This component of dumping is thought to be secondary to hypoglycemia from excessive insulin release.
Dumping syndrome is most noticeable after meals rich in simple carbohydrates (especially sucrose) and high osmolarity. Ingestion of large amounts of fluids may also contribute. Up to 50% of postvagotomy and drainage patients will experience dumping syndrome to some degree. Signs and symptoms often improve with time, but a severe protracted picture can occur in up to 1% of patients.
Dietary modification is the cornerstone of therapy for patients with dumping syndrome. Small, multiple (six) meals devoid of simple carbohydrates coupled with elimination of liquids during meals is important. Antidiarrheals and anticholinergic agents are complimentary to diet. The somatostatin analogue octreotide has been successful in diet refractory cases. This drug is administered subcutaneously (50 g tid), titrated according to clinical response. Recently a long-acting formulation has become available, but its use in dumping syndrome has not been examined.
Up to 10% of patients may seek medical attention for the treatment of postvagotomy diarrhea. This complication is most commonly observed after truncal vagotomy. Patients may complain of intermittent diarrhea that occurs typically 1 to 2 h after meals. Occasionally the symptoms may be severe and relentless. This is due to a motility disorder from interruption of the vagal fibers supplying the luminal gut. Other contributing factors may include decreased absorption of nutrients (see below), increased excretion of bile acids, and release of luminal factors that promote secretion. Diphenoxylate or loperamide is often useful in symptom control. The bile salt-binding agent cholestyramine may be helpful in severe cases. Surgical reversal of a 10-cm segment of jejunum may yield a substantial improvement in bowel frequency in a subset of patients.
Bile Reflux Gastropathy
A subset of post-partial gastrectomy patients will present with abdominal pain, early satiety, nausea, and vomiting, who have as the only finding mucosal erythema of the gastric remnant. Histologic examination of the gastric mucosa reveals minimal inflammation but the presence of epithelial cell injury. This clinical picture is categorized as bile or alkaline reflux gastropathy/gastritis. Although reflux of bile is implicated as the reason for this disorder, the mechanism is unknown. Prokinetic agents (cisapride, 10 to 20 mg before meals and at bedtime) and cholestyramine have been effective treatments. Cisapride may cause cardiac arrhythmias. Severe refractory symptoms may require using either nuclear scanning with 99mTc-HIDA, to document reflux, or an alkaline challenge test, where 0.1 N NaOH is infused into the stomach in an effort to reproduce the patient's symptoms. Surgical diversion of pancreaticobiliary secretions away from the gastric remnant with a Roux-en-Y gastrojejunostomy consisting of a long (50 to 60 cm) Roux limb has been used in severe cases. Bilious vomiting improves, but early satiety and bloating may persist in up to 50% of patients.
Maldigestion and Malabsorption
Weight loss can be observed in up to 60% of patients after partial gastric resection. A significant component of this weight reduction is due to decreased oral intake. However, mild steatorrhea can also develop. Reasons for maldigestion/malabsorption include decreased gastric acid production, rapid gastric emptying, decreased food dispersion in the stomach, reduced luminal bile concentration, reduced pancreatic secretory response to feeding, and rapid intestinal transit.
Decreased serum vitamin B12 levels can be observed after partial gastrectomy. This is usually not due to deficiency of intrinsic factor (IF), since a minimal amount of parietal cells (source of IF) are removed during antrectomy. Reduced vitamin B12 may be due to competition for the vitamin by bacterial overgrowth or inability to split the vitamin from its protein-bound source due to hypochlorhydria.
Iron-deficiency anemia may be a consequence of impaired absorption of dietary iron in patients with a Billroth II gastrojejunotomy. Absorption of iron salts is normal in these individuals; thus a favorable response to oral iron supplementation can be anticipated. Folate deficiency with concomitant anemia can also develop in these patients. This deficiency may be secondary to decreased absorption or diminished oral intake.
Malabsorption of vitamin D and calcium resulting in osteoporosis and osteomalacia is common after partial gastrectomy and gastrojejunostomy (Billroth II). Osteomalacia can occur as a late complication in up to 25% of post-partial gastrectomy patients. Bone fractures occur twice as commonly in men after gastric surgery as in a control population. It may take years before x-ray findings demonstrate diminished bone density. Elevated alkaline phosphatase, reduced serum calcium, bone pain, and pathologic fractures may be seen in patients with osteomalacia. The high incidence of these abnormalities in this subgroup of patients justifies treating them with vitamin D and calcium supplementation indefinitely. Therapy is especially important in females.
The incidence of adenocarcinoma in the gastric stump is increased 15 years after resection. Some have reported a four- to fivefold increase in gastric cancer 20 to 25 years after resection. The pathogenesis is unclear but may involve alkaline reflux, bacterial proliferation, or hypochlorhydria. Endoscopic screening every other year may detect surgically treatable disease.
Severe peptic ulcer diathesis secondary to gastric acid hypersecretion due to unregulated gastrin release from a non- cell endocrine tumor (gastrinoma) defines the components of the ZES. Initially, ZES was typified by aggressive and refractory ulceration in which total gastrectomy provided the only chance for enhancing survival. Today ZES can be cured by surgical resection in up to 30% of patients.
The incidence of ZES varies from 0.1 to 1% of individuals presenting with PUD. Males are more commonly affected than females, and the majority of patients are diagnosed between ages 30 and 50. Gastrinomas are classified into sporadic tumors (more common) and those associated with multiple endocrine neoplasia (MEN) type I (see below).
Hypergastremia originating from an autonomous neoplasm is the driving force responsible for the clinical manifestations in ZES. Gastrin stimulates acid secretion through gastrin receptors on parietal cells and by inducing histamine release from ECL cells. Gastrin also has a trophic action on gastric epithelial cells. Longstanding hypergastrinemia leads to markedly increased gastric acid secretion through both parietal cell stimulation and increased parietal cell mass. The increased gastric acid output leads to the peptic ulcer diathesis, erosive esophagitis, and diarrhea.
Although early studies suggested that the vast majority of gastrinomas occurred within the pancreas, a significant number of these lesions are extrapancreatic. Over 80% of these tumors are found within the hypothetical gastrinoma triangle (confluence of the cystic and common bile ducts superiorly, junction of the second and third portions of the duodenum inferiorly, and junction of the neck and body of the pancreas medially). Duodenal tumors constitute the most common nonpancreatic lesion; up to 50% of gastrinomas are found here. Less common extrapancreatic sites include stomach, bones, ovaries, heart, liver, and lymph nodes. More than 60% of tumors are considered malignant, with up to 30 to 50% of patients having multiple lesions or metastatic disease at presentation. Histologically, gastrin-producing cells appear well differentiated, expressing markers typically found in endocrine neoplasms (chromogranin, neuron-specific enolase).
Gastric acid hypersecretion is responsible for the signs and symptoms observed in patients with ZES. Peptic ulcer is the most common clinical manifestation, occurring in >90% of gastrinoma patients. Initial presentation and ulcer location (duodenal bulb) may be indistinguishable from common PUD. Clinical situations that should create suspicion of gastrinoma are ulcers in unusual locations (second part of the duodenum and beyond), ulcers refractory to standard medical therapy, ulcer recurrence after acid-reducing surgery, or ulcers presenting with frank complications (bleeding, obstruction, and perforation). Symptoms of esophageal origin are present in up to two-thirds of patients with ZES, with a spectrum ranging from mild esophagitis to frank ulceration with stricture and Barrett's mucosa.
Diarrhea is the next most common clinical manifestation in up to 50% of patients. Although diarrhea often occurs concomitantly with acid peptic disease, it may also occur independent of an ulcer. Etiology of the diarrhea is multifactorial, resulting from marked volume overload to the small bowel, pancreatic enzyme inactivation by acid, and damage of the intestinal epithelial surface by acid. The epithelial damage can lead to a mild degree of maldigestion and malabsorption of nutrients. The diarrhea may also have a secretory component due to the direct stimulatory effect of gastrin on enterocytes or the cosecretion of additional hormones from the tumor, such as vasoactive intestinal peptide.
Gastrinomas can develop in the presence of MEN I syndrome (Chap. 93) in approximately 25% of patients. This autosomal dominant disorder involves primarily three organ sites: the parathyroid glands (80 to 90%), pancreas (40 to 80%), and pituitary gland (30 to 60%). The genetic defect in MEN I is in the long arm of chromosome 11 (11q11-q13). In view of the stimulatory effect of calcium on gastric secretion, the hyperparathyroidism and hypercalcemia seen in MEN I patients may have a direct effect on ulcer disease. Resolution of hypercalcemia by parathyroidectomy reduces gastrin and gastric acid output in gastrinoma patients. An additional distinguishing feature in ZES patients with MEN I is the higher incidence of gastric carcinoid tumor development (as compared to patients with sporadic gastrinomas). Gastrinomas tend to be smaller, multiple, and located in the duodenal wall more often than is seen in patients with sporadic ZES. Establishing the diagnosis of MEN I is critical not only from the standpoint of providing genetic counseling to the patient and his or her family but also from the surgical approach recommended.
The first step in the evaluation of a patient suspected of having ZES is to obtain a fasting gastrin level. A list of clinical scenarios that should arouse suspicion regarding this diagnosis is shown in Table 285-10. Fasting gastrin levels are usually <150 pg/mL. Virtually all gastrinoma patients will have a gastrin level >150 to 200 pg/mL. Measurement of fasting gastrin should be repeated to confirm the clinical suspicion.
Multiple processes can lead to an elevated fasting gastrin level (Table 285-11), with gastric hypochlorhydria or achlorhydria being the most frequent causes. Gastric acid induces feedback inhibition of gastrin release. A decrease in acid production will subsequently lead to failure of the feedback inhibitory pathway, resulting in net hypergastrinemia. Gastrin levels will thus be high in patients using antisecretory agents for the treatment of acid peptic disorders and dyspepsia. H. pylori infection can also cause hypergastrinemia.
The next step in establishing a biochemical diagnosis of gastrinoma is to assess acid secretion. Nothing further needs to be done if decreased acid output is observed. In contrast, normal or elevated gastric acid output suggests a need for additional tests. Gastric acid analysis is performed by placing a nasogastric tube in the stomach and drawing samples at 15-min intervals for 1 h during unstimulated or basal state (BAO), followed by continued sampling after administration of intravenous pentagastrin (MAO). Up to 90% of gastrinoma patients may have a BAO of 15 meq/h (normal <4 meq/h). Up to 12% of patients with common PUD may have comparable levels of acid secretion. A BAO/MAO ratio >0.6 is highly suggestive of ZES, but a ratio <0.6 does not exclude the diagnosis.
Gastrin provocative tests have been developed in an effort to differentiate between the causes of hypergastrinemia and are especially helpful in patients with indeterminant acid secretory studies. The tests are the secretin stimulation test, the calcium infusion study, and a standard meal test. In each of these, a fasted patient has an indwelling intravenous catheter in place for serial blood sampling and an intravenous line in place for secretin or calcium infusion. The patient receives either secretion (intravenous bolus of 2 g/kg) or calcium (calcium gluconate, 5 mg/kg body weight over 3 h) or is fed a meal. Blood is then drawn at predetermined intervals (10 min and 1 min before and at 2, 5, 10, 15, 20, and 30 min after injection for secretin stimulation and at 30-min intervals during the calcium infusion). The most sensitive and specific gastrin provocative test for the diagnosis of gastrinoma is the secretin study. An increase in gastrin of 200 pg within 15 min of secretin injection has a sensitivity and specificity of >90% for ZES. The calcium infusion study is less sensitive and specific than the secretin test, with a rise of >400 pg/mL observed in ~80% of gastrinoma patients. The lower accuracy, coupled with it being a more cumbersome study with greater potential for adverse effects, makes calcium infusion less useful and therefore rarely, if ever, utilized. Rarely, one may observe increased BAO and hypergastrinemia in a patient who in the past has been categorized as having G cell hyperplasia or hyperfunction. This set of findings may have been due to H. pylori. The standard meal test was devised to assist in making the diagnosis of G cell-related hyperactivity, by observing a dramatic increase in gastrin after a meal (>200%). This test is not useful in differentiating between G cell hyperfunction and ZES.
Once the biochemical diagnosis of gastrinoma has been confirmed, the tumor must be located. Multiple imaging studies have been utilized in an effort to enhance tumor localization (Table 285-12). The broad range of sensitivity is due to the variable success rates achieved by the different investigative groups. Endoscopic ultrasound (EUS) permits imaging of the pancreas with a high degree of resolution (<5 mm). This modality is particularly helpful in excluding small neoplasms within the pancreas and in assessing the presence of surrounding lymph nodes and vascular involvement. Several types of endocrine tumors express cell-surface receptors for somatostatin. This permits the localization of gastrinomas by measuring the uptake of the stable somatostatin analogue, 111In-pentriotide (octreoscan) with sensitivity and specificity rates of >75%.
Up to 50% of patients have metastatic disease at diagnosis. Success in controlling gastric acid hypersecretion has shifted the emphasis of therapy towards providing a surgical cure. Detecting the primary tumor and excluding metastatic disease are critical in view of this paradigm shift. Once a biochemical diagnosis has been confirmed, the patient should first undergo an abdominal computed tomographic scan, magnetic resonance imaging, or octreoscan (depending on availability) to exclude metastatic disease. Once metastatic disease has been excluded, an experienced endocrine surgeon may opt for exploratory laparotomy with intraoperative ultrasound or transillumination. In other centers, careful examination of the peripancreatic area with EUS, accompanied by endoscopic exploration of the duodenum for primary tumors, will be performed before surgery. Selective arterial secretin injection (SASI) may be a useful adjuvant for localizing tumors in a subset of patients.
Treatment of functional endocrine tumors is directed at ameliorating the signs and symptoms related to hormone overproduction, curative resection of the neoplasm, and attempts to control tumor growth in metastatic disease.
PPIs are the treatment of choice and have decreased the need for total gastrectomy. Initial doses of omeprazole or lansoprazole should be in the range of 60 mg/d. Dosing can be adjusted to achieve a BAO <10 meq/h (at the drug trough) in surgery-naive patients and to <5 meq/h in individuals who have previously undergone an acid-reducing operation. Although the somatostatin analogue has inhibitory effects on gastrin release from receptor-bearing tumors and inhibits gastric acid secretion to some extent, PPIs have the advantage of reducing parietal cell activity to a greater degree.
The ultimate goal of surgery would be to provide a definitive cure. Improved understanding of tumor distribution has led to 10-year disease-free intervals as high as 34% in sporadic gastrinoma patients undergoing surgery. A positive outcome is highly dependent on the experience of the surgical team treating these rare tumors. Surgical therapy of gastrinoma patients with MEN I remains controversial because of the difficulty in rendering these patients disease free with surgery. In contrast to the encouraging postoperative results observed in patients with sporadic disease, only 6% of MEN I patients are disease free 5 years after an operation. Some groups suggest surgery only if a clearly identifiable, nonmetastatic lesion is documented by structural studies. Others advocate a more aggressive approach, where all patients free of hepatic metastasis are explored and all detected tumors in the duodenum are resected; this is followed by enucleation of lesions in the pancreatic head, with a distal pancreatectomy to follow. The outcome of the two approaches has not been clearly defined.
Therapy of metastatic endocrine tumors in general remains suboptimal; gastrinomas are no exception. A host of medical therapeutic approaches including chemotherapy (streptozotocin, 5-fluorouracil, and doxorubicin), IFN-, and hepatic artery embolization lead to significant toxicity without a substantial improvement in overall survival. Surgical approaches including debulking surgery and liver transplantation for hepatic metastasis have also produced limited benefit. Therefore, early recognition and surgery are the only chances for curing this disease.
The 5- and 10-year survival rates for gastrinoma patients are 62 to 75% and 47 to 53%, respectively. Individuals with the entire tumor resected or those with a negative laparotomy have 5- and 10-year survival rates >90%. Patients with incompletely resected tumors have 5- and 10-year survival of 43% and 25%, respectively. Patients with hepatic metastasis have <20% survival at 5 years. Favorable prognostic indicators include primary duodenal wall tumors, isolated lymph node tumor, and undetectable tumor upon surgical exploration. Poor prognostic indicators include hepatic metastases or the presence of Cushing's syndrome in a sporadic gastrinoma patient.
Stress-Related Mucosal Injury
Patients suffering from shock, sepsis, massive burns, severe trauma, or head injury can develop acute erosive gastric mucosal changes or frank ulceration with bleeding. Classified as stress-induced gastritis or ulcers, injury is most commonly observed in the acid-producing (fundus and body) portions of the stomach. The most common presentation is gastrointestinal bleeding, which is usually minimal but can occasionally be life-threatening. Respiratory failure requiring mechanical ventilation and underlying coagulopathy are risk factors for bleeding, which tends to occur 48 to 72 h after the acute injury or insult.
Histologically, stress injury does not contain inflammation or H. pylori; thus "gastritis" is a misnomer. Although elevated gastric acid secretion may be noted in patients with stress ulceration after head trauma (Cushing's ulcer) and severe burns (Curling's ulcer), mucosal ischemia and breakdown of the normal protective barriers of the stomach also play an important role in the pathogenesis. Acid must contribute to injury in view of the significant drop in bleeding noted when acid inhibitors are used as a prophylactic measure for stress gastritis.
Improvement in the general management of intensive care unit patients has led to a significant decrease in the incidence of gastrointestinal bleeding due to stress ulceration. The estimated decrease in bleeding is from 20 to 30% to <15%. This improvement has led to some debate regarding the need for prophylactic therapy. The limited benefit of medical (endoscopic, angiographic) and surgical therapy in a patient with hemodynamically compromising bleeding associated with stress ulcer/gastritis supports the use of preventive measures in high-risk patients (mechanically ventilated, coagulopathy, multiorgan failure, or severe burns). Maintenance of gastric pH >3.5 with continuous infusion of H2 blockers or liquid antacids administered every 2 to 3 h are viable options. Sucralfate slurry (1 g every 4 to 6 h) has also been successful. If bleeding occurs despite these measures, endoscopy, intraarterial vasopressin, or embolization are options. If all else fails, then surgery should be considered. Although vagotomy and antrectomy may be used, the better approach would be a total gastrectomy, which has an exceedingly high mortality rate in this setting.
The term gastritis should be reserved for histologically documented inflammation of the gastric mucosa. Gastritis is not the mucosal erythema seen during endoscopy and is not interchangeable with "dyspepsia." The etiologic factors leading to gastritis are broad and heterogeneous. Gastritis has been classified based on time course (acute vs. chronic), histologic features, and anatomic distribution or proposed pathogenic mechanism (Table 285-13).
The correlation between the histologic findings of gastritis, the clinical picture of abdominal pain or dyspepsia, and endoscopic findings noted on gross inspection of the gastric mucosa is poor. Therefore, there is no typical clinical manifestation of gastritis.
The most common causes of acute gastritis are infectious. Acute infection with H. pylori induces gastritis. However, H. pylori acute gastritis has not been extensively studied. Reported as presenting with sudden onset of epigastric pain, nausea, and vomiting, limited mucosal histologic studies demonstrate a marked infiltrate of neutrophils with edema and hyperemia. If not treated, this picture will evolve into one of chronic gastritis. Hypochlorhydria lasting for up to 1 year may follow acute H. pylori infection.
The highly acidic gastric environment may be one reason why infectious processes of the stomach are rare. Bacterial infection of the stomach or phlegmonous gastritis is a rare potentially life-threatening disorder, characterized by marked and diffuse acute inflammatory infiltrates of the entire gastric wall, at times accompanied by necrosis. Elderly individuals, alcoholics, and AIDS patients may be affected. Potential iatrogenic causes include polypectomy and mucosal injection with India ink. Organisms associated with this entity include streptococci, staphylococci, Escherichia coli, Proteus, and Haemophilus. Failure of supportive measures and antibiotics may result in gastrectomy.
Other types of infectious gastritis may occur in immunocompromised individuals such as AIDS patients. Examples include herpetic (herpes simplex) or CMV gastritis. The histologic finding of intranuclear inclusions would be observed in the latter.
Chronic gastritis is identified histologically by an inflammatory cell infiltrate consisting primarily of lymphocytes and plasma cells, with very scant neutrophil involvement. Distribution of the inflammation may be patchy, initially involving superficial and glandular portions of the gastric mucosa. This picture may progress to more severe glandular destruction, with atrophy and metaplasia. Chronic gastritis has been classified according to histologic characteristics. These include superficial atrophic changes and gastric atrophy.
The early phase of chronic gastritis is superficial gastritis. The inflammatory changes are limited to the lamina propria of the surface mucosa, with edema and cellular infiltrates separating intact gastric glands. Additional findings may include decreased mucus in the mucous cells and decreased mitotic figures in the glandular cells. The next stage is atrophic gastritis. The inflammatory infiltrate extends deeper into the mucosa, with progressive distortion and destruction of the glands. The final stage of chronic gastritis is gastric atrophy. Glandular structures are lost; there is a paucity of inflammatory infiltrates. Endoscopically the mucosa may be substantially thin, permitting clear visualization of the underlying blood vessels.
Gastric glands may undergo morphologic transformation in chronic gastritis. Intestinal metaplasia denotes the conversion of gastric glands to a small intestinal phenotype with small-bowel mucosal glands containing goblet cells. The metaplastic changes may vary in distribution from patchy to fairly extensive gastric involvement. Intestinal metaplasia is an important predisposing factor for gastric cancer (Chap. 90).
Chronic gastritis is also classified according to the predominant site of involvement. Type A refers to the body-predominant form (autoimmune) and type B is the central-predominant form (H. pylori-related). This classification is artificial in view of the difficulty in distinguishing these two entities. The term AB gastritis has been used to refer to a mixed antral/body picture.
Type A Gastritis
The less common of the two forms involves primarily the fundus and body, with antral sparing. Traditionally, this form of gastritis has been associated with pernicious anemia (Chap. 107) in the presence of circulating antibodies against parietal cells and intrinsic factor; thus it is also called autoimmune gastritis. H. pylori infection can lead to a similar distribution of gastritis. The characteristics of an autoimmune picture are not always present.
Antibodies to parietal cells have been detected in >90% of patients with pernicious anemia and in up to 50% of patients with type A gastritis. Anti-parietal cell antibodies are cytotoxic for gastric mucous cells. The parietal cell antibody is directed against H+,K+-ATPase. T cells are also implicated in the injury pattern of this form of gastritis.
Parietal cell antibodies and atrophic gastritis are observed in family members of patients with pernicious anemia. These antibodies are observed in up to 20% of individuals over age 60 and in ~20% of patients with vitiligo and Addison's disease. About half of patients with pernicious anemia have antibodies to thyroid antigens, and about 30% of patients with thyroid disease have circulating anti-parietal cell antibodies. Anti-intrinsic factor antibodies are more specific than parietal cell antibodies for type A gastritis, being present in ~40% of patients with pernicious anemia. Another parameter consistent with this form of gastritis being autoimmune in origin is the higher incidence of specific familial histocompatibility haplotypes such as HLA-B8 and -DR3.
The parietal cell-containing gastric gland is preferentially targeted in this form of gastritis, and achlorhydria results. Parietal cells are the source of intrinsic factor, lack of which will lead to vitamin B12 deficiency and its sequelae (megaloblastic anemia, neurologic dysfunction).
Gastric acid plays an important role in feedback inhibition of gastrin release from G cells. Achlorhydria, coupled with relative sparing of the antral mucosa (site of G cells), leads to hypergastrinemia. Gastrin levels can be markedly elevated (>500 pg/mL) in patients with pernicious anemia. ECL cell hyperplasia with frank development of gastric carcinoid tumors may result from gastrin trophic effects. The role of gastrin in carcinoid development is confirmed by the observation that antrectomy leads to regression of these lesions. Hypergastrinemia and achlorhydria may also be seen in non-pernicious anemia-associated type A gastritis.
Type B gastritis
Type B, or antral-predominant, gastritis is the more common form of chronic gastritis. H. pylori infection is the cause of this entity. Although described as "antral-predominant," this is likely a misnomer in view of studies documenting the progression of the inflammatory process towards the body and fundus of infected individuals. The conversion to a pan-gastritis is time-dependent-estimated to require 15 to 20 years. This form of gastritis increases with age, being present in up to 100% of people over age 70. Histology improves after H. pylori eradication. The number of H. pylori organisms decreases dramatically with progression to gastric atrophy, and the degree of inflammation correlates with the level of these organisms. Early on, with antral-predominant findings, the quantity of H. pylori is highest and a dense chronic inflammatory infiltrate of the lamina propria is noted accompanied by epithelial cell infiltration with polymorphonuclear leukocytes (Fig. 285-12).
Multifocal atrophic gastritis, gastric atrophy with subsequent metaplasia, has been observed in chronic H. pylori-induced gastritis. This may ultimately lead to development of gastric adenocarcinoma (Fig. 285-13; Chap. 90). H. pylori infection is now considered an independent risk factor for gastric cancer. Worldwide epidemiologic studies have documented a higher incidence of H. pylori infection in patients with adenocarcinoma of the stomach as compared to control subjects. Seropositivity for H. pylori is associated with a three- to sixfold increased risk of gastric cancer. This risk may be as high as ninefold after adjusting for the inaccuracy of serologic testing in the elderly. The mechanism by which H. pylori infection leads to cancer is unknown. However, eradication of H. pylori as a general preventative measure for gastric cancer is not recommended.
Infection with H. pylori is also associated with development of a low grade B cell lymphoma, gastric MALT lymphoma (Chap. 112). The chronic T cell stimulation caused by the infection leads to production of cytokines that promote the B cell tumor. Tumor growth remains dependent upon the presence of H. pylori in that its eradication is often associated with complete regression of the tumor. The tumor may take more than a year to regress after treating the infection. Such patients should be followed by EUS every 2 to 3 months. If the tumor is stable or decreasing in size, no other therapy is necessary. If the tumor grows, it may have become a high-grade B cell lymphoma. When the tumor becomes a high-grade aggressive lymphoma histologically, it loses responsiveness to H. pylori eradication.
Treatment in chronic gastritis is aimed at the sequelae and not the underlying inflammation. Patients with pernicious anemia will require parenteral vitamin B12 supplementation on a long-term basis. Eradication of H. pylori is not routinely recommended unless PUD or a low-grade MALT lymphoma is present.
Miscellaneous Forms of Gastritis
Lymphocytic gastritis is characterized histologically by intense infiltration of the surface epithelium with lymphocytes. The infiltrative process is primarily in the body of the stomach and consists of mature T cells and plasmacytes. The etiology of this form of chronic gastritis is unknown. It has been described in patients with celiac sprue, but whether there is a common factor associating these two entities is unknown. No specific symptoms suggest lymphocytic gastritis. A subgroup of patients has thickened folds noted on endoscopy. These folds are often capped by small nodules that contain a central depression or erosion; this form of the disease is called varioliform gastritis. H. pylori probably plays no significant role in lymphocytic gastritis. Therapy with glucocorticoids or sodium cromoglycate has obtained unclear results.
Marked eosinophilic infiltration involving any layer of the stomach (mucosa, muscularis propria, and serosa) is characteristic of eosinophilic gastritis. Affected individuals will often have circulating eosinophilia with clinical manifestation of systemic allergy. Involvement may range from isolated gastric disease to diffuse eosinophilic gastroenteritis. Antral involvement predominates, with prominent edematous folds being observed on endoscopy. These prominent antral folds can lead to outlet obstruction. Patients can present with epigastric discomfort, nausea, and vomiting. Treatment with glucocorticoids has been successful.
Several systemic disorders may be associated with granulomatous gastritis. Gastric involvement has been observed in Crohn's disease. Involvement may range from granulomatous infiltrates noted only on gastric biopsies to frank ulceration and stricture formation. Gastric Crohn's disease usually occurs in the presence of small-intestinal disease. Several rare infectious processes can lead to granulomatous gastritis, including histoplasmosis, candidiasis, syphilis, and tuberculosis. Other unusual causes of this form of gastritis include sarcoidosis, idiopathic granulomatous gastritis, and eosinophilic granulomas involving the stomach. Establishing the specific etiologic agent in this form of gastritis can be difficult, at times requiring repeat endoscopy with biopsy and cytology. Occasionally, a surgically obtained full-thickness biopsy of the stomach may be required to exclude malignancy.
Ménétrier's disease is a rare entity characterized by large, tortuous gastric mucosal folds. The differential diagnosis of large gastric folds includes ZES, malignancy, infectious etiologies (CMV, histoplasmosis, syphilis), and infiltrative disorders such as sarcoidosis. The mucosal folds in Ménétrier's disease are often most prominent in the body and fundus. Histologically, massive foveolar hyperplasia (hyperplasia of surface and glandular mucous cells) is noted, which replaces most of the chief and parietal cells. This hyperplasia produces the prominent folds observed. The pits of the gastric glands elongate and may become extremely tortuous. Although the lamina propria may contain a mild chronic inflammatory infiltrate, Ménétrier's disease is not considered a form of gastritis. The etiology of this unusual clinical picture is unknown. Overexpression of growth factors such as TGF- may be involved in the process.
Epigastric pain at times accompanied by nausea, vomiting, anorexia, and weight loss are signs and symptoms in patients with Ménétrier's disease. Occult gastrointestinal bleeding may occur, but overt bleeding is unusual and, when present, is due to superficial mucosal erosions. Between 20 and 100% of patients (depending on time of presentation) develop a protein-losing gastropathy accompanied by hypoalbuminemia and edema. Gastric acid secretion is usually reduced or absent because of the replacement of parietal cells. Large gastric folds are readily detectable by either radiographic (barium meal) or endoscopic methods. Endoscopy with deep mucosal biopsy (and cytology) is required to establish the diagnosis and exclude the other entities that may present in a similar manner. A nondiagnostic biopsy may lead to a surgically obtained full-thickness biopsy to exclude malignancy.
Medical therapy with anticholinergic agents, prostaglandins, PPIs, prednisone, and H2 receptor antagonists has obtained varying results. Anticholinergics decrease protein loss. A high-protein diet should be recommended to replace protein loss in patients with hypoalbuminemia. Ulcers should be treated with a standard approach. Severe disease with persistent and substantial protein loss may require total gastrectomy. Subtotal gastrectomy is performed by some; it may be associated with higher morbidity and mortality secondary to the difficulty in obtaining a patent and long-lasting anastomosis between normal and hyperplastic tissues.