Sigmoid Colectomy
What the Examiner Expects
Resection of the sigmoid colon with a colorectal anastomosis, the most commonly performed elective colon operation. For diverticular disease, the entire diseased sigmoid must be resected with the distal margin on compliant, non-thickened rectum (the most common technical error is leaving diseased sigmoid and anastomosing to thickened sigmoid, which leads to recurrence). The proximal margin should be on non-inflamed descending colon. For cancer, high ligation of the IMA at its origin is required for lymph node harvest. The left ureter must be identified and protected, typically crossing the left iliac vessels at the pelvic brim.
Key Examiner Focus Points
- Most common indications: diverticular disease (complicated), sigmoid cancer, volvulus
- For cancer: high ligation of IMA for lymph node harvest
- For diverticulitis: ligate IMA distal to left colic takeoff (preserves left colic artery)
- Distal margin must be on the upper rectum (below the rectosigmoid junction)
- Anastomosis to the upper rectum should be tension-free with adequate blood supply
Common Curveballs
Complicated diverticulitis with a phlegmon — can you do a primary anastomosis?
In the elective setting after the inflammation resolves, yes. In the acute setting with a contained phlegmon, manage nonoperatively with antibiotics and percutaneous drainage of any abscess. Operate electively 6–8 weeks later. If emergent surgery is needed (free perforation), Hartmann's procedure is safest in a contaminated field, though primary anastomosis with diverting ileostomy is acceptable in selected patients.
During laparoscopic sigmoid colectomy, you cannot identify the left ureter
Stop and find it before proceeding. Open the retroperitoneum lateral to the sigmoid and trace the ureter from the pelvic brim. Consider ureteral stents preoperatively in reoperative or inflammatory cases. Ureteral injury is a preventable complication — never ligate the IMA without seeing the ureter.
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