Sample · RACS
Malignant left-sided large bowel obstruction with a distended caecum
Colorectal and small bowel · 3 parts · 13 marks. Decide what you would write, then compare with the rubric and model answer. In the app you write it under time and it comes back marked.
Mr Ray Kowalski, 76, presents to a metropolitan emergency department with 4 days of colicky lower abdominal pain, progressive distension and no flatus or stool for 48 hours. He has hypertension and type 2 diabetes and lives independently. Pulse 108, blood pressure 135/80, temperature 37.6 degrees C. His abdomen is grossly distended and tympanic, tender in the right iliac fossa without guarding. Lactate 2.1 mmol/L, white cell count 13.5 x 10^9/L, creatinine 128 micromol/L.
Computed tomography (CT) of the abdomen and pelvis with intravenous contrast shows a 5 cm irregular circumferential mass in the distal sigmoid colon with an abrupt transition, dilated colon proximally with a caecal diameter of 11 cm and a competent ileocaecal valve (small bowel not dilated). There is no free gas or free fluid and no liver lesions.
(a) Outline the significance of the computed tomography findings and your immediate management. 4 marks
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- Closed-loop obstruction: competent ileocaecal valve means the colon cannot decompress into small bowel; this is a surgical emergency (1)
- Caecum is the commonest site of perforation (Laplace law); diameter over about 12 cm, or right iliac fossa tenderness, signals impending ischaemia or perforation; his right iliac fossa tenderness is a warning sign (1)
- Resuscitation: intravenous crystalloid guided by urine output (catheter), correct electrolytes, nasogastric tube if vomiting, analgesia, venous thromboembolism prophylaxis, hold metformin and nephrotoxins (1)
- Decision for intervention within hours (same day), not trial of conservative management; inform theatre and anaesthesia; consent and stoma site marking (1)
- Exclude mimics on the scan and history: volvulus, pseudo-obstruction (no transition point), diverticular stricture; complete staging with CT chest when safe (1)
Significance:
- This is a malignant closed-loop large bowel obstruction. Because the ileocaecal valve is competent, gas and fluid cannot reflux into the small bowel, so pressure keeps rising in the colon.
- By the law of Laplace the caecum, with the widest diameter, has the highest wall tension and is the usual site of perforation. A caecal diameter approaching 12 cm and right iliac fossa tenderness suggest impending caecal ischaemia.
- The appearance (irregular circumferential mass, abrupt transition) is most consistent with sigmoid carcinoma rather than volvulus or pseudo-obstruction.
Immediate management:
1. Resuscitate: two large-bore cannulas, crystalloid boluses, urinary catheter with hourly output, correct potassium and magnesium, nasogastric tube if vomiting, intravenous analgesia; withhold metformin; venous thromboembolism prophylaxis.
2. Bloods: group and hold, coagulation, carcinoembryonic antigen as a baseline.
3. Decide on the same day: he needs decompression within hours, not a period of observation. I would book theatre, discuss with the anaesthetist and the consultant on call (if I am not), consent him including a stoma, and have the stomal therapy nurse mark both iliac fossae.
4. CT chest to complete staging if it does not delay treatment.
(b) Discuss the options for definitive management of the obstruction and justify your choice for Mr Kowalski. 5 marks
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- Hartmann procedure (resection, end colostomy, rectal stump): safest when septic, unstable, ischaemic or perforated proximal colon, or poor physiology; disadvantage high rate of non-reversal (1)
- Resection with primary anastomosis (with or without on-table lavage or defunctioning ileostomy): acceptable in a fit patient with viable colon and no faecal peritonitis (1)
- Self-expanding metal stent as a bridge to surgery: option in selected patients at experienced centres; reduces stoma rate; perforation risk and concern about oncological outcome; contraindicated with signs of perforation or caecal ischaemia (1)
- Subtotal colectomy with ileorectal anastomosis if caecum is ischaemic, serosal tears or synchronous right lesion; consider bowel frequency in the elderly (1)
- Defunctioning loop colostomy/ileostomy alone: palliative or for bridging to neoadjuvant therapy (not relevant for sigmoid cancer unless unresectable) (1)
- Justified choice for this patient: right iliac fossa tenderness makes stenting unattractive; laparotomy, inspect caecum; oncological sigmoid resection with high tie; Hartmann or anastomosis decided on findings and physiology (1)
The options are:
- Emergency oncological resection with end colostomy (Hartmann procedure). Safest when there is faecal contamination, ischaemic proximal colon, haemodynamic instability or poor physiology. Downside: many elderly patients never have the stoma reversed.
- Resection with primary anastomosis, with or without a defunctioning loop ileostomy. Appropriate in a physiologically fit patient with healthy, viable bowel and no peritonitis; the data in selected patients show similar leak rates to elective surgery in experienced hands.
- Subtotal colectomy with ileorectal anastomosis. Chosen if the caecum is ischaemic or has serosal tears, or there is a synchronous proximal lesion. Avoids a stoma but bowel frequency can be troublesome at 76.
- Colonic stent as a bridge to elective surgery in 1-2 weeks. Reduces stoma rates and allows staging and optimisation, but carries a perforation risk and concerns about local recurrence; it is not appropriate with signs of impending perforation or ischaemia and needs an endoscopist available promptly.
- Loop stoma alone: mainly palliative or for unresectable disease.
My choice: Mr Kowalski has right iliac fossa tenderness with a caecum at 11 cm, which I regard as impending caecal ischaemia, so I would not stent. I would perform a midline laparotomy, decompress and inspect the caecum first. If the caecum is viable, I would perform a sigmoid colectomy with high ligation of the inferior mesenteric pedicle. Given his age, diabetes, raised creatinine and a dilated, oedematous proximal colon, I would most likely perform a Hartmann procedure; if he were stable with healthy bowel I would consider a primary anastomosis with a defunctioning ileostomy. If the caecum has serosal tears or is non-viable I would extend to a subtotal colectomy.
He has a Hartmann procedure. Histology: moderately differentiated adenocarcinoma, pT3 N1b (3 of 18 nodes positive), clear margins, no extramural venous invasion. CT chest is clear. He has recovered well and is home on day 9.
(c) Outline his subsequent management and follow-up. 4 marks
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- Present at colorectal multidisciplinary team meeting; stage III disease (1)
- Adjuvant chemotherapy recommended for stage III: fluoropyrimidine with oxaliplatin (CAPOX or FOLFOX), 3 months CAPOX acceptable for lower-risk (T1-3 N1); consider frailty and neuropathy; start within about 8 weeks (1)
- Mismatch repair / microsatellite testing of the tumour (Lynch screening and prognosis) (1)
- Complete colonoscopy of the remaining colon (via stoma and rectal stump) within about 3-6 months as synchronous lesions occur (1)
- Surveillance: carcinoembryonic antigen and CT chest, abdomen and pelvis for about 3-5 years; colonoscopy at 1 year then per guideline; consider Hartmann reversal after chemotherapy if fit, with contrast enema/endoscopy of stump (1)
- Discuss at the colorectal multidisciplinary team meeting: this is stage III (node-positive) colon cancer.
- Refer to medical oncology for adjuvant chemotherapy: a fluoropyrimidine with oxaliplatin. For T3 N1 disease three months of capecitabine and oxaliplatin is an accepted option; at 76 his fitness, renal function and neuropathy risk decide whether oxaliplatin is added or capecitabine alone is used. Aim to start within about eight weeks of surgery.
- Request mismatch repair immunohistochemistry on the specimen if not already done (screen for Lynch syndrome; also informs prognosis).
- He has not had a complete colonoscopy: arrange endoscopy of the colon via the stoma and of the rectal stump within three to six months to exclude synchronous cancers or polyps.
- Surveillance per Cancer Council Australia guidelines: clinical review and carcinoembryonic antigen regularly, CT chest, abdomen and pelvis (for example yearly) for about three to five years, and colonoscopy at one year.
- Stoma: stomal therapy follow-up. Discuss Hartmann reversal after chemotherapy if he is fit and wishes it; check the stump with flexible sigmoidoscopy or contrast study first.
Where candidates lose marks here
- Treating closed-loop obstruction as a candidate for a period of conservative management: examiners expect a decision for intervention within hours.
- Reciting every operation without choosing one for this patient and saying why (the question asks you to justify your choice).
- Offering a stent despite right iliac fossa tenderness that suggests caecal ischaemia.
- Forgetting completion colonoscopy, because the colon was never fully examined before emergency surgery.
- Spending too long on part (a) resuscitation detail: extra detail earns no extra marks.
Original content written for Fellowship Ready, for exam preparation only, not clinical advice. Not affiliated with the Royal Australasian College of Surgeons.