Gastrointestinal Surgery
Oesophagus and stomach
Dysphagia is progressive for solids then liquids in malignancy, but intermittent for both in achalasia. Boerhaave perforation presents with chest pain, subcutaneous emphysema and pleural effusion after vomiting; contrast study and early surgery are key. Peptic ulcer disease: perforation gives sudden severe pain and free air; bleeding stops spontaneously in most, and endoscopy is first-line. Gastric cancer staging uses CT and laparoscopy; the trap is calling a GIST a carcinoma - GISTs are CD117-positive and rarely metastasise to nodes.
Small bowel, appendix and colon
Small bowel obstruction is adhesional in about 80%. Look for strangulation: pain out of proportion, fever, tachycardia, tenderness, rising lactate and a closed-loop configuration. Appendicitis is atypical in the elderly and pregnant; a normal white cell count does not exclude it. Diverticulitis is classified by Hinchey; Hinchey I–II is usually medical, III–IV needs drainage or resection. Colorectal cancer presents with iron-deficiency anaemia on the right and obstruction on the left.
Anorectum and abdominal wall
Benign anal disease is high-yield: fissures are in the midline posterior, painful with defecation, and treated with stool softeners and topical agents; fistulae are classified by Park's rule; haemorrhoids are classified by degree. Inguinal hernia anatomy (deep ring lateral to inferior epigastric vessels, direct medial) is examined repeatedly. A hernia that is tender, irreducible and associated with obstruction is strangulated, not simply incarcerated. Richter's hernia strangulates part of the bowel wall without obstruction.
Rule of thumb
Never label abdominal pain in a woman of childbearing age as appendicitis without a pregnancy test. For obstruction, the decision for theatre hinges on strangulation, not on the number of air-fluid levels.