Gastrointestinal and Colorectal Surgery
This domain tests the acute abdomen and the elective colorectal cancer pathway: diagnosis, staging, timing of surgery, and the choice between resection, stoma and conservative treatment. Expect scenarios where the decision to operate depends on a single CT finding.
Acute presentations
- Appendicitis: Alvarado score plus ultrasound or CT; appendicectomy for most, antibiotics alone only in selected uncomplicated cases. A phlegmon is treated with antibiotics and drainage, with interval appendicectomy debated.
- Small bowel obstruction: fluids, nasogastric tube, CT to find the transition point and exclude closed loop or strangulation. Operate for strangulation, closed loop, peritonitis or failure of conservative management at 24-48 hours.
- Perforated peptic ulcer: omental (Graham) patch, peritoneal lavage, then Helicobacter eradication.
- Diverticulitis: Hinchey I-II antibiotics; III purulent peritonitis with lavage or resection; IV faecal peritonitis with Hartmann resection or primary anastomosis in selected patients.
Colorectal cancer
- Right colon: iron-deficiency anaemia and a mass; right hemicolectomy with ileocolic anastomosis; obstruction is uncommon.
- Left colon: change in bowel habit and obstruction; consider a stent as a bridge to surgery, or Hartmann versus resection with anastomosis.
- Rectum: neoadjuvant chemoradiotherapy for locally advanced disease (T3/T4 or N+), then total mesorectal excision.
- Staging: CT chest, abdomen and pelvis, pelvic MRI for rectal cancer, baseline CEA, and complete colonoscopy.
Worked example
A 65-year-old with distension and vomiting has a CT showing a closed-loop obstruction at the ileocaecal valve with a 4 cm caecal mass. Reasoning: a closed loop with a competent valve risks perforation and ischaemia, so decompress endoscopically only as a temporising measure in a high-risk patient; here, resuscitate and operate. A right hemicolectomy treats the obstruction and the cancer in one operation, with primary anastomosis because the colon is unprepared but the field is not faeculent.
Traps
- Assuming obstruction always means a left-sided cancer - right colon cancer obstructs less often but does occur.
- Treating Hinchey IV diverticulitis with antibiotics and observation.
- Forgetting synchronous tumours: examine the whole colon after emergency resection.
- Delaying surgery for a small bowel obstruction that a CT shows is a closed loop.