The stem
A 25-year-old man presents with constipation, abdominal distension and discomfort.
Abdominal X-ray and CTImages on Radiopaedia
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Case courtesy of Andrea Molinari, 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
A grossly dilated loop of large bowel with a central dense cleft, giving the "coffee bean" sign, and an air-fluid level in the dilated colon.
Question 2What is the diagnosis?Show the model answer
Sigmoid volvulus.
Question 3Which signs confirm it on CT?Show the model answer
The whirl sign, where the mesentery and bowel loops twist around a fixed point; a beak-shaped narrowing at the point of twist; and the split-wall sign, where twisted mesenteric fat separates the walls of the sigmoid.
Question 4How is it managed?Show the model answer
If there is no peritonitis or bowel ischaemia, endoscopic decompression with a flatus tube. Emergency surgery if the bowel is gangrenous or perforated, or decompression fails. Elective resection is considered afterwards because recurrence is common.
After you answerThe teaching pointShow
Sigmoid volvulus is classically a disease of elderly, constipated or institutionalised patients, but this patient was 25. He was treated successfully with endoscopic decompression.
Related: Model clerking: bowel obstruction →
Source case on Radiopaedia: “Sigmoid volvulus”, by Andrea Molinari.
This station page is shared under CC BY-NC-SA 3.0, the licence of the Radiopaedia case it uses.