The stem
A 50-year-old woman has worsening abdominal pain, no bowel movement for a week, and nausea and vomiting.
Abdominal X-ray and CTImages on Radiopaedia
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Case courtesy of Thuan Tzen Koh, Radiopaedia.org. View the case. Licensed CC BY-NC-SA 3.0.
The examiner’s questions
Question 1Describe the abdominal X-ray.Show the model answer
Distended large bowel containing faeces, with no gas in the rectum and no free gas.
Question 2What does the CT show?Show the model answer
A 2.5 cm circumferential stenosing lesion of the distal sigmoid colon, with dilated, faeces-filled colon above it, and moderate ascites.
Question 3Why is the caecum at risk of perforation?Show the model answer
If the ileocaecal valve is competent, the colon becomes a closed loop. The caecum has the widest diameter, so its wall is under the greatest tension and it is the commonest site of perforation.
Question 4What are the management options?Show the model answer
Resuscitation and staging. Emergency resection, often a Hartmann's procedure, or a defunctioning stoma; in selected patients a colonic stent as a bridge to elective surgery. Decisions are made with the multidisciplinary team.
After you answerThe teaching pointShow
In a patient over 50 with large bowel obstruction and no volvulus, the cause is cancer until proved otherwise.
Related: Model clerking: rectal bleeding →
Source case on Radiopaedia: “Large bowel obstruction secondary to colon cancer”, by Thuan Tzen Koh.
This station page is shared under CC BY-NC-SA 3.0, the licence of the Radiopaedia case it uses.