Sigmoid volvulus

Case contributed by Dr Seamus O'Flaherty


Two days of abdominal pain and distension.

Patient Data

Age: 40 years
Gender: Male

Massive gaseous colonic dilatation. Moderate fecal loading in the rectum. No obvious air-fluid levels. Highly suspicious of large bowel obstruction with transition point in left lower quadrant and large bowel loops extending to right upper quadrant. Etiology suggestive of sigmoid volvulus. No hemoperitoneum. ​

Upward deviation of the mediastinal structures and compression of the lung bases. There is atelectasis and mild prominence of the vascular structures but no pulmonary consolidation.


There is prominent dilatation of the large bowel, particularly of the proximal sigmoid colon and ascending colon which is displaced. Maximum colonic diameter of 19 cm. Whirl sign present on coronal slices, at the level of the sigmoid mesentery, identifying the site of a sigmoid volvulus. 


Intra-operative findings of a massive sigmoid volvulus with dusky colored bowel wall and areas of macroscopic necrosis. There was no perforation. Patient proceeded to Hartmann's procedure with end colostomy formation. 

Case Discussion

This case provides an excellent example of a massive sigmoid volvulus with classic imaging findings.

A sigmoid volvulus arises in the pelvis from the left lower quadrant, often with a "coffee-bean" sign present. Because the sigmoid colon rotates around its mesentery, this creates a whirling pattern of the vessels at the base of the mesentery. This can be appreciated on the CT coronal reformats (whirl or whirlpool sign). 

As the large bowel obstruction is rather distal, there is dilatation of the descending, transverse and ascending colon, creating a closed-loop obstruction at the ileocecal valve. The large bowel loops dilate up toward the right upper quadrant and there are usually very few air-fluid levels. 

In comparison, a cecal volvulus arises in the right lower quadrant and the dilated bowel extends toward the left upper quadrant. The distal large bowel collapses whilst the small bowel becomes distended. This is often associated with many air-fluid levels. 

This patient had 48 hours of symptoms prior to presentation and, due to obstructed blood flow through the sigmoid mesentery, had ischemic bowel that was not viable and required resection. 

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Case information

rID: 77499
Published: 18th May 2020
Last edited: 20th Jan 2021
Inclusion in quiz mode: Included
Institution: Epworth Healthcare

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