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Large bowel obstruction, volvulus and Ogilvie's syndrome
Large bowel obstruction in an adult is cancer until proven otherwise; sigmoid volvulus is usually untwisted endoscopically and then resected, caecal volvulus is operated on, and obstruction without a mechanical cause (Ogilvie's) is treated by correcting the cause and then with neostigmine.
Why it matters in the exam
Large bowel obstruction questions ask you to separate four causes: an obstructing tumour (the most common), sigmoid volvulus, caecal volvulus and pseudo-obstruction (Ogilvie's). Each appears in a different setting: tumour — an older patient with weight loss and a change in bowel habit; sigmoid volvulus — an institutionalised older patient with chronic constipation and neurological disease; caecum — a somewhat younger adult; Ogilvie's — an inpatient after surgery, childbirth or severe illness, with electrolyte disturbances and opioids.
The exam also tests the "closed loop" concept: when a competent ileocaecal valve stops gas from returning to the small bowel, the caecum distends, and a diameter above 12 cm sharply raises the risk of perforation. You are asked about the treatment of each cause: endoscopic detorsion and a rectal tube for sigmoid volvulus, followed by resection before discharge, since it tends to recur; surgery for caecal volvulus; and for pseudo-obstruction — conservative care, correction of potassium and magnesium and stopping opioids, and if there is no improvement — neostigmine with cardiac monitoring, then colonoscopic decompression.
Key points
- A tumour is the leading cause of large bowel obstruction.
- Caecum above 12 cm — danger of perforation.
- Sigmoid volvulus — endoscopic detorsion, then resection during the same admission.
- Caecal volvulus — surgery.
- Ogilvie's — conservative care and electrolyte correction, then neostigmine 2 mg with cardiac monitoring.
Summary table
| Cause | Who and what | Imaging | Treatment |
|---|---|---|---|
| Obstructing tumour | Older adult, weight loss, change in bowel habit; the most common cause | CT: mass with dilated bowel above | Right side — resection with primary anastomosis; left side — resection (sometimes Hartmann's) or a stent as a bridge to surgery |
| Sigmoid volvulus | Older, institutionalised, constipated, neurological disease | X-ray: a dilated "coffee bean" loop rising from the pelvis; CT | Detorsion by sigmoidoscopy and a rectal tube, then sigmoid resection in the same admission; gangrene or peritonitis — immediate surgery |
| Caecal volvulus | Somewhat younger adult | Dilated caecum displaced to the left upper abdomen; CT | Surgery: right hemicolectomy |
| Pseudo-obstruction (Ogilvie's) | Inpatient after surgery, childbirth or severe illness; opioids, electrolyte disturbance | Marked colonic dilatation without a transition point | Conservative care, correct electrolytes, stop opioids; neostigmine 2 mg intravenously with cardiac monitoring; colonoscopic decompression |
| Impending perforation | Caecum above 12 cm, local tenderness, peritoneal signs | CT: free or intramural air | Urgent surgery |
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Sources
- ASCRS Clinical Practice Guidelines for the Management of Colonic Volvulus and Acute Colonic Pseudo-Obstruction, 2016 — Endoscopic and operative management
- WSES guidelines on obstructive left colon carcinoma, 2018 (update 2017) — Emergency resection versus stenting
- Sabiston Textbook of Surgery, 21st edition (2022) — Colon and Rectum
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.