Alimentary Tract and Abdominal Surgery
Core concepts
Acute abdominal pain requires an organized history, focused examination, and selective laboratory and imaging studies. Understand appendicitis, biliary colic and cholecystitis, small- and large-bowel obstruction, hernia, perforated viscus, gastrointestinal bleeding, mesenteric ischemia, and inflammatory bowel disease. For bowel obstruction, distinguish simple from closed-loop or strangulated obstruction; fever, tachycardia, localized tenderness, metabolic acidosis, and pain out of proportion suggest ischemia and operative urgency. For upper GI bleeding, resuscitate first, start a proton-pump inhibitor, and arrange endoscopy within 24 hours; suspected variceal bleeding also needs vasoactive therapy and antibiotics. Lower GI bleeding in a stable patient is evaluated by colonoscopy after bowel preparation, while unstable or massive bleeding may require angiography or surgery.
Traps
Do not anchor on gastroenteritis in an elderly or anticoagulated patient. A normal plain film does not exclude perforation or ischemia; CT is more sensitive. Murphy sign supports cholecystitis but is not specific. In appendicitis, atypical presentations are common in pregnancy, older adults, and immunocompromised patients. Avoid immediate surgery for uncomplicated diverticulitis; most cases are managed medically. A virgin abdomen after prior surgery may still have obstruction, but consider malignancy and hernia.
Worked example
A 68-year-old with generalized peritonitis, free air on CT, and hypotension has a perforated viscus. Resuscitate, give broad-spectrum antibiotics, and proceed to source control rather than ordering more imaging. Rule of thumb: peritonitis, pneumoperitoneum, or strangulation equals operative evaluation; stable obstruction without these features often starts nonoperative with decompression and serial reassessment.