Abdominal and Gastrointestinal Disorders
Core approach
Approach abdominal pain by anatomy, acuity, and physiologic stability. Core diagnoses include appendicitis, cholecystitis, cholangitis, pancreatitis, perforated viscus, bowel obstruction, mesenteric ischemia, diverticulitis, GI bleeding, hernia, and abdominal aortic aneurysm. Use history, examination, laboratory studies, and targeted imaging; remember that elderly, immunosuppressed, and pregnant patients may lack classic findings. Assess volume status and transfusion needs in GI bleeding, and involve surgery early for peritonitis, perforation, ischemia, or strangulation.
Traps
Normal laboratory values do not exclude surgical disease. Pain out of proportion to examination suggests mesenteric ischemia, especially with atrial fibrillation or vascular disease. Elderly patients with bowel obstruction may have little pain or vomiting. A normal lipase does not exclude pancreatitis, and an elevated lipase is not specific. Avoid giving opioids as a substitute for serial abdominal examinations. In lower GI bleeding, hypotension and anticoagulation increase risk; do not delay resuscitation for colonoscopy.
Worked example
A 70-year-old with atrial fibrillation develops severe periumbilical pain, and the abdomen is soft with minimal tenderness. Lactate is elevated. Think acute mesenteric ischemia and obtain CT angiography urgently while resuscitating and involving surgery. Rule of thumb: pain out of proportion plus vascular risk equals mesenteric ischemia until excluded.
Key concepts
Recognize Charcot triad and Reynolds pentad in cholangitis. Suspect strangulation with obstruction when fever, tachycardia, localized tenderness, or acidosis appear. In upper GI bleeding, resuscitate, risk-stratify, and arrange endoscopy; in perforation, give antibiotics and surgical consultation.