Medical School · Year 3 · General Surgery · includes a quiz and discussion video

Seminar 09: Gastric Surgery

Year 3: General Surgery Clerkship

Learning Objectives

By the end of this seminar, students will be able to:

1. Describe gastric anatomy and physiology
2. Evaluate and manage peptic ulcer disease
3. Recognize indications for gastric surgery
4. Diagnose and stage gastric cancer
5. Describe surgical procedures for gastric disease
6. Manage postgastrectomy syndromes

I. Gastric Anatomy

The stomach is a J-shaped organ divided into five anatomic regions that have distinct functional and clinical significance. The cardia is the narrow region at the gastroesophageal junction, containing primarily mucus-secreting cells. The fundus is the dome-shaped portion above the level of the gastroesophageal junction, serving as a reservoir and containing acid-secreting parietal cells. The body comprises the largest portion of the stomach and is the principal site of parietal cells and chief cells responsible for acid and pepsin production. The antrum is the distal third extending to the pylorus and contains gastrin-producing G cells that regulate acid secretion. The pylorus is a muscular sphincter controlling gastric emptying into the duodenum.

The arterial blood supply to the stomach is remarkably redundant, deriving from branches of the celiac trunk that form anastomotic arcades along both curvatures. The left gastric artery arises directly from the celiac trunk and is the largest vessel supplying the stomach, coursing along the lesser curvature. The right gastric artery typically arises from the proper hepatic artery and joins the left gastric along the lesser curvature. The short gastric arteries arise from the splenic artery and supply the fundus, while the left gastroepiploic artery, also from the splenic artery, supplies the greater curvature. The right gastroepiploic artery arises from the gastroduodenal artery and courses along the greater curvature to anastomose with the left gastroepiploic.

Lymphatic drainage of the stomach follows the arterial blood supply and is organized into regional nodal stations that are important for cancer staging and lymphadenectomy. The perigastric nodes (station N1) lie immediately adjacent to the stomach along the curvatures. The nodes along the celiac axis and its branches (station N2) include those along the left gastric, common hepatic, and splenic arteries. The extent of lymphadenectomy is described as D1 (perigastric nodes only) or D2 (perigastric plus celiac axis nodes), with D2 lymphadenectomy standard for gastric cancer in experienced centers, requiring harvest of at least 15 lymph nodes for adequate staging.

The innervation of the stomach is critical for understanding both physiologic acid secretion and the historical role of vagotomy in ulcer surgery. The vagus nerves enter the abdomen through the esophageal hiatus, with the anterior trunk (predominantly left vagus) giving off the hepatic branch before continuing along the lesser curvature. The posterior trunk (predominantly right vagus) gives off the celiac branch before descending along the posterior stomach. The criminal nerve of Grassi is a branch from the posterior vagus to the fundus that, if not divided during vagotomy, can lead to recurrent ulceration. Vagal stimulation promotes acid secretion through direct stimulation of parietal cells and indirect stimulation via gastrin release from G cells.

<image>Panel A: External anatomy of the stomach showing cardia, fundus, body, antrum, and pylorus with corresponding locations. Panel B: Arterial blood supply from celiac trunk showing left gastric, right gastric, short gastrics, and gastroepiploic vessels forming anastomotic arcades. Panel C: Lymph node stations N1 and N2 along the arterial supply relevant for D1 and D2 lymphadenectomy. Panel D: Vagal innervation showing anterior and posterior trunks with hepatic, celiac, and criminal nerve of Grassi branches.</image>

II. Gastric Physiology

The gastric mucosa contains several specialized cell types that work together to accomplish the stomach's digestive functions. Parietal cells, located primarily in the fundus and body, secrete hydrochloric acid via the hydrogen-potassium ATPase (proton pump) and also produce intrinsic factor essential for vitamin B12 absorption in the terminal ileum. Chief cells, also in the fundus and body, secrete pepsinogen, which is converted to the proteolytic enzyme pepsin in the acidic gastric environment. G cells in the antrum produce gastrin, the primary hormonal stimulant of acid secretion. D cells produce somatostatin, which inhibits both acid secretion and gastrin release. Enterochromaffin-like cells in the body release histamine, which stimulates parietal cells through H2 receptors.

Gastric acid secretion is regulated through three overlapping phases that correspond to the stages of food ingestion and digestion. The cephalic phase is mediated by the vagus nerve and initiated by the sight, smell, taste, or thought of food, accounting for approximately 30 percent of total acid secretion. The gastric phase is triggered by distension and the presence of peptides and amino acids in the stomach, stimulating both vagal reflexes and gastrin release, and accounts for approximately 60 percent of acid secretion. The intestinal phase results from amino acids and peptides entering the duodenum, contributing the remaining 10 percent. Inhibition of acid secretion occurs when antral pH falls below 3, triggering somatostatin release from D cells, which suppresses both gastrin release and parietal cell activity.

Gastric motility serves the functions of storage, mixing, and controlled emptying of gastric contents into the duodenum. Receptive relaxation is a vagally mediated reflex that allows the fundus to accommodate ingested material without significant increase in intragastric pressure. Peristaltic contractions originating from the gastric pacemaker in the body propagate toward the pylorus at approximately three cycles per minute, mixing food with gastric secretions to form chyme. The pylorus relaxes synchronously with antral contractions to allow controlled emptying of chyme into the duodenum. The migrating motor complex occurs during fasting and consists of waves of contraction that clear residual material from the stomach, accounting for the "hunger pangs" experienced during prolonged fasting.

The stomach possesses robust mucosal defense mechanisms that protect against autodigestion by its own acid and pepsin. A mucus-bicarbonate barrier covers the epithelial surface, creating a pH gradient from approximately 7 at the cell surface to 1 to 2 in the lumen. Prostaglandins, particularly PGE2 and PGI2, maintain mucosal blood flow, stimulate mucus and bicarbonate secretion, and promote epithelial cell renewal. Rapid epithelial turnover allows quick replacement of damaged cells, with complete surface renewal occurring every 3 to 5 days. Mucosal blood flow removes back-diffused hydrogen ions and provides nutrients for the energy-intensive processes of mucus secretion and cell renewal. Disruption of these protective mechanisms by NSAIDs, Helicobacter pylori, or severe physiologic stress leads to peptic ulceration.

<image>Panel A: Distribution of gastric cell types showing parietal cells and chief cells in fundus/body versus G cells and D cells in antrum. Panel B: Regulation of acid secretion showing cephalic, gastric, and intestinal phases with their respective mediators and contributions. Panel C: Coordinated gastric motility showing receptive relaxation, peristalsis, and pyloric function during emptying. Panel D: Mucosal defense mechanisms including mucus-bicarbonate barrier, prostaglandin effects, and epithelial renewal.</image>

III. Peptic Ulcer Disease

Peptic ulcer disease results from an imbalance between aggressive factors (acid and pepsin) and protective mucosal defense mechanisms, with the two predominant etiologies being Helicobacter pylori infection and nonsteroidal anti-inflammatory drug use. H. pylori is a gram-negative spiral bacterium that colonizes the gastric antrum and is present in approximately 70 percent of gastric ulcers and 90 percent of duodenal ulcers. The organism produces urease that generates ammonia, creating a favorable microenvironment while triggering inflammatory responses that impair mucosal defenses. NSAIDs inhibit cyclooxygenase enzymes that produce protective prostaglandins, thereby reducing mucus secretion, bicarbonate production, and mucosal blood flow. Physiologic stress from critical illness produces stress ulcers (Curling's ulcers in burns, Cushing's ulcers in head injury), while Zollinger-Ellison syndrome causes ulceration through gastrin-secreting tumors producing massive acid hypersecretion.

The clinical presentation of peptic ulcer disease differs somewhat between gastric and duodenal ulcers, though considerable overlap exists. Duodenal ulcers classically cause epigastric pain that occurs hours after meals and often awakens patients at night, with relief provided by food or antacids that buffer gastric acid. Gastric ulcers typically cause pain that is exacerbated by eating, presumably due to distension stimulating the ulcer. Alarm symptoms requiring urgent evaluation include weight loss, anemia, melena or hematemesis, early satiety, and new dysphagia, as these may indicate complications or underlying malignancy. Complications of peptic ulcer disease include hemorrhage from erosion into blood vessels, perforation with peritonitis, gastric outlet obstruction from edema or scarring, and penetration into adjacent organs such as the pancreas.

Diagnosis of peptic ulcer disease relies on endoscopy, which allows visualization, biopsy, and therapeutic intervention. Esophagogastroduodenoscopy visualizes ulcers and permits biopsy to assess for malignancy in gastric ulcers and to test for H. pylori through rapid urease test or histologic examination. H. pylori testing can also be performed noninvasively using the urea breath test or stool antigen test, which are useful for diagnosis and confirming eradication following treatment. Complete blood count may reveal anemia from chronic occult bleeding. Serum gastrin level is measured when Zollinger-Ellison syndrome is suspected, particularly in patients with multiple ulcers, ulcers in atypical locations, or ulcers refractory to standard therapy.

Medical management of peptic ulcer disease centers on acid suppression and H. pylori eradication when present. Proton pump inhibitors are the most effective acid-suppressing agents, achieving ulcer healing rates exceeding 90 percent with 8 to 12 weeks of treatment. H. pylori eradication requires combination therapy, with the standard regimen being triple therapy consisting of a PPI plus clarithromycin plus either amoxicillin or metronidazole for 14 days. Eradication should be confirmed with urea breath test or stool antigen at least 4 weeks after completing therapy and 2 weeks after stopping PPI. Patients requiring continued NSAID therapy should receive concomitant PPI prophylaxis. Smoking cessation is strongly advised as smoking impairs ulcer healing and increases recurrence risk. Discontinuation of NSAIDs, when feasible, removes a major contributing factor.

<image>Panel A: Comparison of gastric ulcer showing antral location and margins with potential for malignancy versus duodenal ulcer with post-bulbar location. Panel B: Pathophysiology diagram showing H. pylori mechanisms including urease production, inflammation, and mucosal damage. Panel C: Endoscopic appearance of benign gastric ulcer with clean base versus bleeding ulcer with visible vessel. Panel D: H. pylori eradication regimens showing triple therapy components and confirmation testing timeline.</image>

IV. Surgical Treatment of Peptic Ulcer

Surgical intervention for peptic ulcer disease has declined dramatically with the advent of effective acid-suppressing medications and H. pylori eradication therapy, but remains indicated for specific complications. Perforation presents as sudden severe abdominal pain with peritonitis and free air on imaging, requiring urgent operative intervention. Hemorrhage refractory to endoscopic therapy (failure of two endoscopic attempts or recurrent bleeding) mandates surgical control. Gastric outlet obstruction from chronic ulceration may require surgery when endoscopic dilation fails. Intractability, defined as failure to heal despite maximum medical therapy including confirmed H. pylori eradication, rarely necessitates surgery in the modern era but may be considered for carefully selected patients.

Surgical management of bleeding peptic ulcer depends on the ulcer location and source of hemorrhage. Duodenal ulcers, particularly posterior bulbar ulcers, most commonly bleed from erosion into the gastroduodenal artery. The surgical approach involves duodenotomy with direct suture ligation of the bleeding vessel using figure-of-eight stitches placed above and below the ulcer to control both the gastroduodenal artery and the retroduodenal vessels. For gastric ulcers, excision or wedge resection allows both hemorrhage control and pathological examination to exclude malignancy. An acid-reducing procedure such as truncal vagotomy was historically performed concurrently, though the universal use of postoperative PPI therapy and H. pylori treatment has reduced this practice.

Perforated peptic ulcer is a surgical emergency requiring prompt operative intervention after initial resuscitation. Graham patch repair, or omental patch closure, remains the standard approach, involving suture closure of the perforation with omentum buttressing the repair to provide a blood supply and seal the defect. This can be performed laparoscopically in stable patients by experienced surgeons. The peritoneal cavity is thoroughly irrigated to remove contamination. Definitive acid-reducing procedures such as vagotomy are rarely performed acutely given the availability of PPI therapy and H. pylori treatment. All patients should undergo H. pylori testing and eradication, which effectively prevents recurrence in infected patients.

Historical acid-reducing procedures developed before the PPI era remain relevant for understanding gastrointestinal anatomy and rare contemporary indications. Truncal vagotomy divides both vagal trunks at the esophageal hiatus, eliminating the cephalic phase of acid secretion but also causing gastric atony requiring a drainage procedure (pyloroplasty or gastrojejunostomy). Highly selective vagotomy (parietal cell vagotomy) denervates only the acid-secreting portion of the stomach while preserving antral innervation and thus normal emptying, but is technically demanding and has higher recurrence rates. Antrectomy with vagotomy removes the gastrin-producing antrum and eliminates vagal stimulation, providing the lowest recurrence rate but highest morbidity. Reconstruction following antrectomy uses either Billroth I (gastroduodenostomy) or Billroth II (gastrojejunostomy) anastomosis, with the latter more commonly performed due to technical ease and reduced tension.

<image>Panel A: Operative photograph showing duodenotomy with exposure of posterior duodenal ulcer eroding into gastroduodenal artery with suture ligation technique. Panel B: Graham patch repair technique showing perforation closure with omental buttress secured with interrupted sutures. Panel C: Vagotomy types comparing truncal vagotomy with pyloroplasty versus highly selective vagotomy preserving antral innervation. Panel D: Reconstruction options after antrectomy showing Billroth I gastroduodenostomy versus Billroth II gastrojejunostomy anatomy.</image>

V. Gastric Cancer

Gastric adenocarcinoma is one of the leading causes of cancer death worldwide, though its incidence varies dramatically by geographic region. The disease is most common in East Asia, Eastern Europe, and parts of South America, with Japan and Korea having incidence rates 5 to 10 times higher than Western countries, leading to robust screening programs in these nations. Risk factors include H. pylori infection (classified as a Group 1 carcinogen by WHO), dietary factors including high salt intake and consumption of smoked or preserved foods, smoking, family history, and precursor conditions including chronic atrophic gastritis, intestinal metaplasia, and adenomatous polyps. Two histologic subtypes are recognized by the Lauren classification: intestinal type, which is more common in high-incidence areas and follows the gastritis-metaplasia-dysplasia-carcinoma sequence, and diffuse type, which is more common in younger patients and includes signet-ring cell carcinoma.

Clinical presentation of gastric cancer is often insidious, with early disease typically asymptomatic and advanced disease presenting with nonspecific symptoms. Weight loss is the most common symptom at diagnosis, reflecting both the catabolic state of malignancy and impaired oral intake. Vague epigastric discomfort or dyspepsia may be dismissed as benign disease. Dysphagia occurs with proximal tumors involving the cardia, while nausea, vomiting, and early satiety suggest distal obstruction or linitis plastica (diffuse infiltrating cancer causing a rigid, nondistensible "leather bottle" stomach). Gastrointestinal bleeding presents as melena, hematemesis, or iron-deficiency anemia. Physical examination findings in advanced disease may include a palpable epigastric mass, ascites, left supraclavicular lymphadenopathy (Virchow's node), periumbilical nodule (Sister Mary Joseph nodule), or Blumer's shelf on rectal examination.

Staging evaluation combines endoscopic assessment of the primary tumor with cross-sectional imaging and surgical staging. Upper endoscopy with biopsy establishes the diagnosis and allows assessment of tumor location and extent. Endoscopic ultrasound provides the most accurate T staging for early tumors and evaluates perigastric lymph nodes. CT of the chest, abdomen, and pelvis assesses for distant metastases and local tumor extent. PET-CT has variable sensitivity for gastric cancer (lower for mucinous and signet-ring tumors) but may detect occult metastases. Diagnostic laparoscopy with peritoneal cytology is recommended for locally advanced tumors (cT3 or higher) to detect radiologically occult peritoneal disease that would preclude curative resection, present in up to 30 percent of patients with seemingly resectable disease on imaging.

The TNM staging system categorizes gastric cancer by depth of invasion, nodal involvement, and metastatic status. T1 tumors are confined to the mucosa (T1a) or submucosa (T1b), T2 tumors invade the muscularis propria, T3 tumors penetrate through the muscularis into the subserosa, T4a tumors perforate the serosa (visceral peritoneum), and T4b tumors invade adjacent structures. Nodal staging is based on the number of positive regional lymph nodes: N1 indicates 1 to 2 positive nodes, N2 indicates 3 to 6 positive nodes, and N3 indicates 7 or more positive nodes. Stage groupings range from Stage I (early localized disease) with 5-year survival of 60 to 80 percent, to Stage IV (metastatic disease) with 5-year survival below 5 percent. Adequate staging requires examination of at least 15 lymph nodes.

<image>Panel A: World map showing geographic distribution of gastric cancer incidence with highest rates in East Asia, Eastern Europe, and South America. Panel B: Endoscopic appearance of gastric cancer showing ulcerated mass and comparison of intestinal versus diffuse (linitis plastica) subtypes. Panel C: Physical examination findings in advanced disease including Virchow's node, Sister Mary Joseph nodule, and Blumer's shelf locations. Panel D: T stage diagram showing depth of invasion from mucosa through serosa and into adjacent structures.</image>

VI. Gastric Cancer Treatment

Early gastric cancer confined to the mucosa without lymph node involvement may be treated with endoscopic resection in carefully selected cases. Endoscopic mucosal resection and endoscopic submucosal dissection can achieve curative resection for well-differentiated tumors less than 2 centimeters without ulceration and without lymphovascular invasion. The advantages include preservation of the stomach with maintained quality of life and avoidance of surgical morbidity. However, strict criteria must be met, and complete pathological examination of the specimen is essential to confirm curative resection. Tumors with submucosal invasion (T1b) have significant risk of lymph node metastases (up to 20 percent) and generally require surgical resection with lymphadenectomy.

Surgical resection with adequate margins and lymphadenectomy is the cornerstone of curative treatment for resectable gastric cancer. The extent of gastrectomy depends on tumor location, with the goal of achieving at least 4 to 6 centimeter proximal margins. Subtotal (distal) gastrectomy is appropriate for tumors of the antrum and distal body that can be resected with adequate margins while preserving the proximal stomach. Total gastrectomy is required for proximal tumors, tumors of the gastric body that cannot be adequately cleared with subtotal resection, and linitis plastica due to submucosal spread. D2 lymphadenectomy, removing both perigastric and celiac axis nodal stations, has become the standard at experienced centers, improving staging accuracy and likely improving survival without significantly increasing morbidity when splenectomy and distal pancreatectomy are avoided.

Reconstruction following gastrectomy restores alimentary continuity while minimizing postgastrectomy complications. Following subtotal gastrectomy, Billroth I reconstruction (gastroduodenostomy) provides the most physiologic reconstruction but may have tension; Billroth II (gastrojejunostomy) is technically easier and more commonly performed. Roux-en-Y reconstruction diverts biliopancreatic secretions away from the gastric remnant, reducing bile reflux gastritis, and is increasingly preferred. Following total gastrectomy, Roux-en-Y esophagojejunostomy is the standard reconstruction, with the alimentary limb typically 50 to 60 centimeters in length. A jejunal pouch may be created to provide a reservoir, potentially improving early nutritional status, though long-term benefits are debated.

Perioperative systemic therapy improves outcomes for locally advanced gastric cancer compared to surgery alone. Neoadjuvant chemotherapy (or perioperative chemotherapy given before and after surgery) has become the standard approach in many Western countries based on the MAGIC and FLOT trials, which demonstrated survival benefits with perioperative FLOT (5-FU, leucovorin, oxaliplatin, docetaxel) or ECF regimens. Adjuvant chemoradiation following surgery is an alternative approach supported by the INT-0116 trial, particularly when neoadjuvant therapy was not administered. In East Asia, where D2 lymphadenectomy is standard, adjuvant chemotherapy alone has shown benefit. Patients with unresectable locally advanced disease may receive chemotherapy with reassessment for potential conversion to resectability. Palliative chemotherapy extends survival in metastatic disease, and targeted therapy with trastuzumab is added for HER2-positive tumors.

<image>Panel A: Endoscopic submucosal dissection technique for early gastric cancer showing injection, circumferential incision, and en bloc resection. Panel B: Extent of gastric resection comparing subtotal gastrectomy for distal tumors versus total gastrectomy for proximal tumors with margin requirements. Panel C: Reconstruction options including Billroth I, Billroth II, and Roux-en-Y configurations following partial and total gastrectomy. Panel D: Multimodality treatment algorithm showing perioperative chemotherapy approach versus adjuvant therapy following surgery.</image>

VII. Postgastrectomy Syndromes

Dumping syndrome is the most common postgastrectomy complication, occurring in up to 25 to 50 percent of patients following gastric surgery, though severe symptoms requiring intervention affect only 5 to 10 percent. Early dumping occurs within 15 to 30 minutes of eating and results from rapid emptying of hyperosmolar contents into the small bowel, causing fluid shifts into the intestinal lumen with subsequent vasomotor symptoms including diaphoresis, palpitations, flushing, tachycardia, and hypotension, along with gastrointestinal symptoms including cramping, bloating, and diarrhea. Late dumping occurs 2 to 3 hours postprandially and results from reactive hypoglycemia caused by rapid glucose absorption triggering excessive insulin release, presenting with sweating, tremor, weakness, confusion, and hunger. Dietary modifications are the cornerstone of management, including small frequent meals, avoiding concentrated sugars and liquids with meals, increasing protein and fat intake, and lying down after eating.

Alkaline reflux gastritis occurs when biliopancreatic secretions reflux into the gastric remnant following procedures that disrupt the pylorus, particularly Billroth II gastrectomy. Patients experience constant burning epigastric pain unrelated to meals and often unresponsive to acid-suppressing medications, along with nausea and bilious vomiting that does not relieve the pain (unlike dumping, where vomiting may provide relief). Endoscopy reveals erythematous, edematous mucosa with bile staining, and biopsy shows foveolar hyperplasia and inflammatory changes. Medical management with cholestyramine to bind bile acids and prokinetic agents has limited efficacy. Surgical treatment with Roux-en-Y reconstruction to divert biliopancreatic secretions away from the gastric remnant is the definitive treatment for refractory cases.

Afferent and efferent loop syndromes are mechanical complications specific to Billroth II reconstruction. Afferent loop syndrome results from obstruction or stasis in the afferent limb (the duodenal stump and proximal jejunum carrying biliopancreatic secretions), causing distension with accumulation of bile and pancreatic juice, presenting as postprandial abdominal pain relieved by bilious vomiting that does not contain food. Chronic afferent loop syndrome may lead to bacterial overgrowth with steatorrhea and vitamin deficiencies. Acute complete obstruction is a surgical emergency that can lead to afferent loop perforation. Efferent loop syndrome involves obstruction of the efferent limb, presenting similarly to small bowel obstruction with abdominal distension and vomiting. Both conditions are treated with surgical revision, typically conversion to Roux-en-Y reconstruction.

Long-term nutritional complications following gastrectomy require awareness and proactive management. Iron deficiency anemia results from loss of gastric acid required for iron solubilization and conversion to the absorbable ferrous form, often necessitating oral or intravenous iron supplementation. Vitamin B12 deficiency develops after total gastrectomy (or over time after subtotal gastrectomy) due to loss of intrinsic factor, requiring parenteral B12 supplementation every 1 to 3 months. Calcium and vitamin D malabsorption contribute to metabolic bone disease, requiring supplementation and monitoring of bone density. Weight loss is expected following gastrectomy, with patients typically losing 10 to 15 percent of body weight after subtotal gastrectomy and more after total gastrectomy, necessitating nutritional counseling and possibly involvement of a dietitian.

<image>Panel A: Pathophysiology of early dumping showing rapid gastric emptying, osmotic fluid shifts, and resulting vasomotor and GI symptoms versus late dumping with reactive hypoglycemia timeline. Panel B: Endoscopic appearance of alkaline reflux gastritis showing bile-stained erythematous mucosa in gastric remnant. Panel C: Anatomy of afferent loop syndrome showing dilated obstructed afferent limb in Billroth II reconstruction. Panel D: Algorithm for nutritional monitoring following gastrectomy including iron, B12, calcium, and vitamin D supplementation schedule.</image>

VIII. Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumors are mesenchymal neoplasms arising from the interstitial cells of Cajal, the pacemaker cells that coordinate gastrointestinal motility. The stomach is the most common location, accounting for approximately 60 percent of GISTs, followed by the small intestine at 30 percent. The vast majority of GISTs harbor activating mutations in the KIT (CD117) or PDGFRA genes, which drive tumor cell proliferation and provide therapeutic targets. The biologic behavior of GIST spans a spectrum from benign to frankly malignant, with risk stratification based on tumor size, mitotic rate, and anatomic location, with non-gastric GISTs having higher malignant potential at any given size.

Clinical presentation of gastric GIST varies with tumor size and location. Small GISTs are often discovered incidentally during imaging or endoscopy performed for other indications. Symptomatic tumors may cause gastrointestinal bleeding from mucosal ulceration (the most common presentation), vague abdominal discomfort, or early satiety from mass effect. Large tumors may present as a palpable abdominal mass. Unlike gastric adenocarcinoma, GISTs grow as submucosal masses that expand outward and may present with large size while still potentially resectable. Obstruction is uncommon because GISTs typically do not narrow the lumen circumferentially.

Diagnostic evaluation of suspected GIST includes imaging and tissue diagnosis. CT scan reveals a well-defined, enhancing mass that may show central necrosis or ulceration in larger tumors. Endoscopy demonstrates a submucosal mass with intact overlying mucosa, though central ulceration may be present. Endoscopic ultrasound allows characterization of the tumor layer of origin (muscularis propria) and guides fine-needle aspiration for tissue diagnosis. Immunohistochemistry confirms the diagnosis with approximately 95 percent of GISTs positive for CD117 (c-KIT) and 70 percent positive for DOG1. Mutational analysis identifies KIT exon 11 mutations (most common and most responsive to therapy), KIT exon 9 mutations (more common in intestinal GIST), PDGFRA mutations, and wild-type tumors.

Surgical resection is the primary treatment for localized GIST, with the goal of complete resection with negative margins. Unlike gastric adenocarcinoma, wide margins are not required, and a 1 to 2 centimeter margin or resection with clear margins is adequate. Lymphadenectomy is not performed because GISTs rarely metastasize to lymph nodes. Wedge resection or segmental gastrectomy is appropriate for most gastric GISTs, preserving as much stomach as possible. Adjuvant imatinib, a tyrosine kinase inhibitor targeting KIT and PDGFRA, is recommended for 3 years following resection of high-risk GISTs (large tumors, high mitotic rate, or tumor rupture), reducing recurrence rates by approximately 50 percent. For metastatic or unresectable GIST, imatinib is the first-line systemic therapy, with sunitinib and regorafenib available for resistant disease.

<image>Panel A: Endoscopic and endoscopic ultrasound appearance of gastric GIST showing submucosal mass arising from muscularis propria layer. Panel B: CT scan demonstrating large enhancing gastric GIST with central necrosis and comparison with smaller incidental GIST. Panel C: Risk stratification based on size and mitotic rate showing categories from very low to high risk. Panel D: Surgical resection specimen showing wedge gastrectomy with preserved gastric architecture and clear margins.</image>

IX. Other Gastric Conditions

Gastric polyps are relatively common findings on upper endoscopy, with management determined by histologic type and associated risks. Fundic gland polyps are the most common type, representing 50 to 70 percent of gastric polyps, and are associated with chronic PPI use. These polyps are almost universally benign and typically require no treatment or surveillance. Hyperplastic polyps arise in the setting of chronic gastritis, including H. pylori-associated gastritis, and have low but measurable malignant potential (less than 2 percent), with larger polyps (greater than 1 centimeter) warranting removal and surveillance. Adenomatous polyps are true neoplastic lesions with significant malignant potential (approximately 30 to 40 percent for larger lesions) and should be completely excised, with subsequent surveillance similar to colonic adenoma surveillance.

Gastric volvulus is a rare but potentially life-threatening condition in which the stomach rotates around itself, causing obstruction and potential ischemia. Organoaxial volvulus, rotation along the longitudinal axis connecting the cardia and pylorus, is more common and often associated with paraesophageal hernia. Mesenteroaxial volvulus, rotation along the transverse axis, is less common and more frequently associated with acute symptoms. The classic presentation is Borchardt's triad: severe epigastric pain and distension, retching with inability to vomit, and inability to pass a nasogastric tube. Acute gastric volvulus requires emergent surgical intervention with reduction, assessment of gastric viability, and gastropexy to prevent recurrence. Chronic or intermittent volvulus may be managed electively with repair of any associated hernia and gastropexy.

Bariatric surgery for morbid obesity encompasses several gastric procedures with different mechanisms and outcomes. Sleeve gastrectomy has become the most commonly performed bariatric operation, involving vertical resection of approximately 80 percent of the stomach along the greater curvature, creating a tubular stomach with restricted capacity and reduced ghrelin production. Roux-en-Y gastric bypass creates a small proximal gastric pouch connected to a Roux limb, combining restriction with malabsorption and hormonal changes that improve glucose metabolism. Adjustable gastric banding, while declining in popularity, uses an adjustable silicone band to create restriction. Biliopancreatic diversion with duodenal switch is a primarily malabsorptive procedure reserved for super-obese patients. Sleeve gastrectomy and gastric bypass produce similar long-term weight loss (approximately 25 to 30 percent excess weight loss), though bypass may be superior for type 2 diabetes remission.

Gastric lymphoma, primarily mucosa-associated lymphoid tissue (MALT) lymphoma and diffuse large B-cell lymphoma, represents approximately 3 to 5 percent of gastric malignancies. MALT lymphoma is strongly associated with chronic H. pylori infection, which provides antigenic stimulation driving lymphoproliferation. Early-stage MALT lymphoma localized to the mucosa and submucosa may regress with H. pylori eradication alone, with complete remission achieved in 60 to 80 percent of patients. Higher-stage MALT lymphoma and diffuse large B-cell lymphoma require chemotherapy (typically R-CHOP regimen) with or without radiation therapy. Surgical resection is rarely indicated and is reserved for complications such as bleeding, perforation, or obstruction during treatment. Following H. pylori eradication, surveillance endoscopy is performed every 3 to 6 months initially to confirm regression and detect relapse.

<image>Panel A: Endoscopic appearance comparing fundic gland polyps (small, sessile, multiple) with hyperplastic polyp and adenomatous polyp morphology. Panel B: Anatomic diagram of gastric volvulus showing organoaxial rotation along the longitudinal axis versus mesenteroaxial rotation along the transverse axis. Panel C: Bariatric surgery procedures comparing sleeve gastrectomy, Roux-en-Y gastric bypass, and adjustable gastric band anatomy. Panel D: Endoscopic appearance of gastric MALT lymphoma showing mucosal irregularity and post-H. pylori eradication regression.</image>

X. Zollinger-Ellison Syndrome

Zollinger-Ellison syndrome is caused by gastrin-secreting neuroendocrine tumors (gastrinomas) that cause massive acid hypersecretion resulting in severe peptic ulcer disease, diarrhea, and esophagitis. The gastrinoma triangle, defined by the junction of the cystic and common bile duct superiorly, the junction of the second and third portions of the duodenum inferiorly, and the junction of the neck and body of the pancreas medially, contains the vast majority of sporadic gastrinomas. Approximately 75 percent are sporadic while 25 percent occur in the setting of multiple endocrine neoplasia type 1 (MEN1), which presents at younger ages with multiple tumors and associated parathyroid hyperplasia and pituitary adenomas. Gastrinomas are malignant in 60 to 90 percent of cases, with metastases to regional lymph nodes and liver determining prognosis.

Clinical features of Zollinger-Ellison syndrome reflect the consequences of chronic acid hypersecretion. Peptic ulcer disease is the hallmark, often with multiple ulcers, ulcers in atypical locations (distal duodenum, jejunum), ulcers resistant to standard therapy, or rapidly recurring ulcers after treatment. Diarrhea occurs in up to 70 percent of patients due to acid-induced damage to the intestinal mucosa, inactivation of pancreatic lipase causing fat malabsorption, and direct effects of high gastrin on intestinal motility. Severe gastroesophageal reflux disease with esophagitis and stricture formation may occur. The diagnosis should be suspected in any patient with refractory ulcer disease, multiple ulcers, ulcers associated with diarrhea, or family history of MEN1.

Diagnosis of Zollinger-Ellison syndrome requires demonstration of elevated fasting gastrin levels with confirmation of acid hypersecretion. Fasting serum gastrin exceeding 1000 pg/mL (normal less than 100 pg/mL) in the setting of gastric pH below 2 is virtually diagnostic. However, elevated gastrin can occur with achlorhydria (atrophic gastritis, PPI use), so gastric pH must be confirmed to be acidic, which excludes the common situation of elevated gastrin from hypochlorhydria. For borderline gastrin elevations, the secretin stimulation test demonstrates a paradoxical rise in gastrin (greater than 120 pg/mL increase) in gastrinoma patients, whereas gastrin decreases or remains stable in other conditions. Following biochemical diagnosis, localization studies including CT, MRI, somatostatin receptor scintigraphy (octreotide scan), and endoscopic ultrasound identify the primary tumor and assess for metastatic disease.

Management of Zollinger-Ellison syndrome includes control of acid hypersecretion and treatment of the gastrinoma itself. Proton pump inhibitor therapy at high doses (often 2 to 3 times standard dosing or more) effectively controls acid secretion in most patients, healing ulcers and preventing complications. Unlike other peptic ulcer disease, lifelong therapy is required unless the gastrinoma is completely resected. Surgical resection is indicated for sporadic gastrinomas without liver metastases, as resection can achieve cure in approximately 30 to 40 percent of cases. Surgery for MEN1-associated gastrinomas is controversial because tumors are typically multiple and recurrence is common, though resection may be considered for tumors exceeding 2 centimeters given higher malignant potential. Metastatic disease is managed with somatostatin analogs, cytotoxic chemotherapy, targeted therapies, and hepatic-directed treatments for liver metastases.

<image>Panel A: Gastrinoma triangle anatomy showing the boundaries defined by the cystic duct, second-third duodenal junction, and pancreatic neck-body junction. Panel B: CT and octreotide scan showing gastrinoma in the duodenal wall with hepatic metastases. Panel C: Secretin stimulation test tracing showing paradoxical gastrin rise diagnostic of gastrinoma versus normal response. Panel D: Surgical exploration showing duodenotomy with identification of small duodenal gastrinoma.</image>

Summary

• Gastric anatomy: 5 regions (cardia, fundus, body, antrum, pylorus); blood supply from celiac trunk branches with redundant arcades
• Gastric physiology: parietal cells produce acid, G cells produce gastrin; cephalic, gastric, and intestinal phases of acid secretion
• Peptic ulcer disease: H. pylori and NSAIDs are main causes; treat with PPI and H. pylori eradication
• Surgical indications: perforation, hemorrhage uncontrolled endoscopically, obstruction, intractability
• Gastric cancer: H. pylori is a risk factor; surgery with D2 lymphadenectomy; Roux-en-Y reconstruction after total gastrectomy
• Postgastrectomy syndromes: dumping (early and late), alkaline reflux gastritis, nutritional deficiencies (iron, B12)
• GIST: c-kit positive mesenchymal tumor; surgical resection without lymphadenectomy; adjuvant imatinib for high-risk tumors
• Gastric volvulus: Borchardt's triad (pain, retching without vomiting, inability to pass NG tube); emergent reduction and gastropexy
• Zollinger-Ellison syndrome: gastrinoma causing acid hypersecretion; elevated gastrin with low pH; high-dose PPI therapy
• Bariatric surgery: sleeve gastrectomy most common; Roux-en-Y gastric bypass for diabetes and reflux

Key Terms

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