Colorectal Surgery
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Direct answer
Vascular anatomy dictates the operation in colorectal surgery: a right hemicolectomy ligates the ileocolic (and right colic) vessels and joins ileum to transverse colon, a splenic flexure tumour needs an extended right hemicolectomy, and left-sided disease is governed by the inferior mesenteric artery. Complete mesocolic excision with central vascular ligation — Hohenberger's principle, the colon-cancer counterpart of total mesorectal excision — is the oncological standard, and laparoscopic resection is routine. Anastomotic leak, running at roughly 3–5 per cent, is the complication every decision orbits: low rectal joins are defunctioned with a loop ileostomy, and contaminated emergencies end in a Hartmann's procedure rather than a risky primary anastomosis.
What you must remember
- Caecum and ascending colon: right hemicolectomy with ileocolic vessel ligation; hepatic flexure and proximal transverse colon: extended right hemicolectomy adding the middle colic vessels.
- Splenic flexure: extended right hemicolectomy with ileocolic or ileorectal anastomosis, or a left hemicolectomy — the watershed segment approached from either side.
- Descending and sigmoid colon: left hemicolectomy or sigmoid colectomy ligating the inferior mesenteric artery below or at the left colic origin.
- Complete mesocolic excision (CME): sharp dissection along the mesocolic fascia with central tie of the feeding artery and full mesenteric lymphovascular clearance — Hohenberger's Erlangen improvement in outcomes.
- High versus low IMA ligation trades extra nodal yield (high) against better blood supply and preserved autonomic nerves (low) — oncological outcomes are broadly equivalent.
- Anastomotic leak presents classically around day 5–7 with tachycardia, fever, peritonism or an unexplained arrhythmia in the elderly; tachycardia alone on day 5 warrants CT with contrast.
- A defunctioning loop ileostomy is standard for anastomoses within roughly 5–6 cm of the anal verge, irradiated pelvises, and emergencies where a primary join is still attempted.
- Hartmann's procedure — sigmoid colectomy, end colostomy, closed rectal stump — is the default for perforated sigmoid diverticulitis and obstructed unprepared sigmoid cancer, reversed in only about half; about 5 per cent harbour synchronous cancers, so colonoscopy or CT colonography precedes elective surgery, and obstructing left cancers can be bridged with a stent to permit one-stage surgery.
Working through a splenic flexure tumour
A 66-year-old woman has an obstructing adenocarcinoma at the splenic flexure with proximal dilatation. The reasoning begins with blood supply: the splenic flexure is the watershed between the middle and left colic territories, its marginal artery often tenuous. That drives two choices. First, the extent — extended right hemicolectomy removing terminal ileum to descending colon, ligating ileocolic, right and middle colic vessels, with an ileosigmoid anastomosis; alternatively a left hemicolectomy with high IMA ligation. Second, the obstruction — she is obstructed but stable, so a stent as a bridge to surgery decompresses the bowel, converts an emergency into a semi-elective resection and often avoids a stoma. At laparotomy the CME plane is respected, the omentum goes with the specimen, and at least twelve lymph nodes are sought. The anastomosis is checked with an air-leak test, and a proximal ileostomy decided by bowel health and contamination. This chain — vascular territory first, obstruction second, leak risk third — is what turns a surgical question into an exam answer.
How the examiner frames high ligation
The high-versus-low IMA ligation question is a trap for candidates who answer with conviction on the wrong axis. High ligation at the IMA origin gives the apical nodes and a longer specimen but devascularises the left colon and approaches the preaortic plexus; low ligation below the left colic preserves hypogastric nerves and colonic perfusion. Randomised comparisons show no meaningful survival difference, so ligation level follows the tumour's lymphovascular pedicle and the blood supply needed for the anastomosis — not ideology. Adding that the ascending left colic branch is preserved when possible shows the judgement examiners reward.
Frequently asked questions
Which operation suits a caecal cancer?
A right hemicolectomy with ligation of the ileocolic vessels and an ileocolic anastomosis, extended to include the middle colic vessels for hepatic flexure tumours.
What does complete mesocolic excision add over conventional resection?
Sharp mesocolic-plane dissection with central vascular ligation delivers an intact mesentery, more lymph nodes and lower local recurrence — the colon counterpart of total mesorectal excision.
When is a defunctioning loop ileostomy added?
For low rectal anastomoses, irradiated pelvises, emergency joins with unprepared bowel, and whenever a leak would be poorly tolerated — it turns a catastrophe into a managed complication.
How does an anastomotic leak typically present?
Around day 5–7 with tachycardia, fever, abdominal signs or, in the elderly, confusion or atrial fibrillation; unexplained tachycardia after colorectal surgery is a leak until excluded by CT.
What is the role of colonic stenting in obstruction?
Bridge-to-surgery decompression in obstructing left-sided cancer allowing staging and one-stage resection, or definitive palliation in advanced disease; perforation and migration are the key risks.
Why is Hartmann's reversal not always performed?
Because patients are often elderly and comorbid and reversal is major pelvic surgery; about half are never reversed — a fact to discuss at consent.