Ch19: Gastroduodenal Diseases（胃十二指肠疾病）

Preparatory Mindset

Gastroduodenal surgery = peptic ulcer disease (PUD) & its complications (perforation, bleeding, obstruction), and gastric cancer. The lecture (Dr. Pan, 15.8KB) follows the classic teaching: "No acid, no ulcer" → the H. pylori revolution, the ulcer complications (perforation → peritonitis; bleeding → gastroduodenal/left gastric arteries; pyloric obstruction), and gastric cancer (presentation, staging, D2 gastrectomy).

Exam mindset: PUD complications and their surgical management; the surgical indications for peptic ulcer (perforation, hemorrhage, obstruction, penetration, malignancy risk); gastric cancer staging & D2 lymphadenectomy; the blood supply (left gastric artery for lesser-curvature bleeding — ties into Anatomy Ch17). The prep PDFs add the definitions (胃大部切除术, 毕I/毕II式).

Core Concepts

1. Peptic ulcer disease — basics (MUST KNOW)

| Feature | Duodenal ulcer | Gastric ulcer | |---|---|---| | Age/type | Younger, M>F | Older | | Acid | ↑ (hypersecretion) | Normal/low | | H. pylori | ~90% | ~70% | | Pain | Epigastric, relieved by food | Worse with food | | Malignant risk | Essentially none | GU may be malignant — biopsy |

1. Perforation (急性穿孔) — ulcer through the wall → sudden severe epigastric pain, board-like rigidity, free air under the diaphragm (pneumoperitoneum), peritonitis → emergency: laparotomy (patch/Graham omentopexy) or laparoscopic repair + lavage; or non-operative (resuscitation, NPO, NG, antibiotics, PPI) in selected cases 2. Hemorrhage (出血) — erosion into an artery: - DU (posterior wall) → gastroduodenal artery — the classic - GU (lesser curvature) → left gastric artery - GU (posterior wall) → splenic artery (see Anatomy Ch17) - Clinical: hematemesis/melena, shock; treatment: resuscitation, PPI infusion, endoscopy (injection, thermal, clips), angiography/embolization; surgery if endoscopic control fails (oversew/ulcer excision + vagotomy/acid-reducing) 3. Pyloric obstruction (幽门梗阻) — chronic ulcer scarring → vomiting of undigested food, dehydration, hypokalemic hypochloremic metabolic alkalosis; treatment: NG decompression, fluids, treat ulcer; surgery (drainage + vagotomy or distal gastrectomy) if persistent 4. Penetration — ulcer into adjacent organ (pancreas, liver) → pain radiating to the back; medical therapy

• Definition: ulceration of the mucosa exposed to acid-pepsin — gastric ulcer (GU) & duodenal ulcer (DU)
• Pathogenesis: "No acid, no ulcer" — but "if acid, why ulcer (CM exam tested)?" → imbalance of aggressive (acid, pepsin, H. pylori, NSAIDs) vs defensive (mucus, bicarbonate, blood flow, prostaglandins)
• H. pylori (HP): the major cause — colonizes gastric mucosa, increases acid (DU) or impairs defense (GU); eradication (triple therapy: PPI + amoxicillin + clarithromycin ± metronidazole) heals ulcers & prevents recurrence
• NSAIDs: inhibit COX → ↓ prostaglandins → ↓ mucus/bicarbonate → ulcer (esp. GU); stop NSAIDs + PPI
• DU vs GU:
• Complications of PUD (MUST KNOW):
• Stress ulcer: critically ill (ICU, burns — Curling, head injury — Cushing); prophylaxis with PPI

2. Surgical indications for peptic ulcer (MUST KNOW)

• Perforation (emergency)
• Hemorrhage not controlled endoscopically / recurrent
• Pyloric obstruction (non-resolving)
• Penetration
• Suspected malignancy (gastric ulcer not healed on repeat endoscopy/biopsy)
• Failed medical therapy (intractable — rare now with HP eradication/PPI)
• Complications of surgery → now uncommon because of HP eradication

3. Gastric surgery (MUST KNOW)

- Distal (partial) gastrectomy (胃大部切除术): for distal gastric cancer & complicated DU — Billroth I (gastroduodenostomy) or Billroth II (gastrojejunostomy) - Total gastrectomy: for proximal/diffuse gastric cancer; esophagojejunostomy (Roux-en-Y) - Laparoscopic vs open

- Dumping syndrome: rapid gastric emptying → early (hypovolemia: sweating, palpitations, diarrhea after meals — small frequent meals, low carb) & late (hypoglycemia — reactive) - Anastomotic leak (day 3-7: fever, peritonitis) - Bleeding (anastomotic) - Afferent/efferent loop syndrome (B-II) - Alkaline reflux gastritis, bile reflux - Nutritional: B12 deficiency (pernicious — total gastrectomy → B12 lifelong), iron deficiency, weight loss, malabsorption, post-vagotomy diarrhea - Roux stasis syndrome

• Gastrectomy types:
• Vagotomy (for DU historically): truncal, selective, highly selective (parietal cell) — with drainage (pyloroplasty/gastrojejunostomy) for truncal; reduces acid; now rarely first-line (HP eradication)
• Post-gastrectomy complications (MUST KNOW):

4. Gastric cancer (MUST KNOW)

- Early gastric cancer: endoscopic resection (EMR/ESD) if very early (mucosal, well-diff, <2 cm, no nodes) or gastrectomy - Resectable advanced: radical gastrectomy (distal/total) + D2 lymphadenectomy (perigastric + nodes along named vessels); curative R0 resection; neoadjuvant/adjuvant chemo (perioperative FLOT/ECF) improves survival; ± chemoradiation - Unresectable/metastatic: palliative — chemo (HER2+: trastuzumab), symptom control (stenting, bypass, palliative resection for bleeding/obstruction), best supportive care - Lymphadenectomy D1 vs D2: D1 = perigastric nodes; D2 = D1 + nodes along left gastric, common hepatic, splenic, celiac arteries (standard for cure in Asia)

• Epidemiology: common in East Asia (China, Japan, Korea); H. pylori (major risk), diet (salted/smoked), smoking, family history, pernicious anemia, prior partial gastrectomy
• Types: intestinal type (older, better prognosis — related to HP, diet) vs diffuse type (younger, worse — signet ring cells, linitis plastica); early gastric cancer (EGC: confined to mucosa/submucosa regardless of nodes) vs advanced
• Presentation: often asymptomatic early; weight loss, epigastric pain, early satiety, anorexia, anemia (iron deficiency), vomiting (obstruction), hematemesis/melena, palpable mass; left supraclavicular node (Virchow's — via thoracic duct), Krukenberg (ovarian mets), Blumer's shelf (rectal shelf), Sister Mary Joseph nodule (umbilicus)
• Diagnosis: endoscopy + biopsy (gold standard); staging with CT (chest/abdomen/pelvis), EUS (depth), laparoscopy (peritoneal mets); tumor markers (CEA, CA19-9)
• Staging: TNM (tumor depth T1-4, nodes N, mets M) → stage I-IV
• Treatment (MUST KNOW):
• Prognosis: depends on stage; early = excellent; advanced/metastatic = poor
• Linitis plastica: diffuse infiltrating ("leather bottle") stomach — poor prognosis

High-Yield Points

• "No acid, no ulcer"; H. pylori & NSAIDs are the causes; triple therapy eradicates HP
• PUD complications: perforation (board-like rigidity, free air — emergency), bleeding (DU→gastroduodenal a., GU→left gastric/splenic a.), pyloric obstruction (hypokalemic hypochloremic alkalosis), penetration (back pain)
• Surgical indications: perforation, uncontrolled/recurrent bleeding, obstruction, penetration, suspected malignancy
• GU must be biopsied (malignant potential); DU essentially never malignant
• Gastric cancer: H. pylori & diet; intestinal vs diffuse; EGC (mucosa/submucosa)
• Metastatic signs: Virchow's node, Krukenberg tumor, Blumer's shelf
• Diagnosis: endoscopy + biopsy; staging CT/EUS/laparoscopy
• Treatment: radical gastrectomy + D2 lymphadenectomy; perioperative chemo; HER2+ → trastuzumab; endoscopic resection for very early
• Post-gastrectomy: dumping, B12 deficiency (total gastrectomy — lifelong B12), anastomotic leak
• DU pain relieved by food; GU worse with food

Topic Summary

Peptic ulcer: H. pylori & NSAIDs; DU (younger, acid hypersecretion, no malignant risk) vs GU (older, must biopsy). Complications: perforation (emergency — free air, board-like rigidity; patch repair), hemorrhage (DU→gastroduodenal artery; GU→left gastric/splenic artery; endoscopic control first), pyloric obstruction (hypokalemic hypochloremic alkalosis), penetration (back pain). Surgical indications: perforation, uncontrolled bleeding, obstruction, penetration, suspected malignancy. Surgery: gastrectomy (B-I/B-II/Roux-en-Y) ± vagotomy; complications (dumping, B12 deficiency, leak). Gastric cancer: H. pylori & diet; intestinal vs diffuse; diagnosis by endoscopy + biopsy; treatment = radical gastrectomy + D2 lymphadenectomy ± perioperative chemo; metastatic signs (Virchow, Krukenberg, Blumer's shelf); HER2+ → trastuzumab. Early gastric cancer may be resected endoscopically.