Alimentary Tract
Core concepts
The alimentary tract questions reward a disciplined approach: localize the lesion, then reason about obstruction, inflammation, perforation, and ischemia as separate mechanisms. Know the classic presentations of appendicitis, small-bowel obstruction (SBO), large-bowel obstruction, diverticulitis, and peptic ulcer disease, and understand which findings push you toward operative versus nonoperative management.
Traps
- SBO vs. ileus: SBO has crampy pain, vomiting, and hyperactive early bowel sounds; ileus has diffuse distension with absent sounds and often a recent operation or medication trigger. Questions test whether you can distinguish them from the history alone.
- Right- vs. left-sided diverticulitis: right-sided disease mimics appendicitis; left-sided is the classic sigmoid picture. Don't anchor on age.
- Perforation signs: free air may be absent on plain film; clinical peritonitis and hemodynamics drive the decision, not the radiograph.
- Upper GI bleeding: the most common cause of significant upper GI hemorrhage is peptic ulcer disease; variceal bleeding requires different initial priorities (resuscitation and portal hypertension management).
Rule of thumb
For any acute abdomen, ask: Is there peritonitis, hemodynamic instability, or evidence of strangulation/perforation? If yes, operate. If no, image and observe. For SBO, a trial of nonoperative management is reasonable in the stable patient without fever, leukocytosis, or peritoneal signs, but a closed-loop obstruction or strangulation is a surgical emergency.
Worked example
A 62-year-old with crampy abdominal pain, vomiting, and a distended abdomen after prior pelvic surgery: suspect adhesive SBO. Obtain CT with contrast to identify a transition point and rule out strangulation. Stable, no peritonitis → nasogastric decompression and serial exams; worsening or peritoneal signs → laparotomy.