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Sigmoid volvulus

Sigmoid volvulus is a cause of large bowel obstruction and occurs when the sigmoid colon twists on its mesentery, the sigmoid mesocolon.

Large bowel volvulus accounts for ~5% of all large bowel obstructions, with ~60% of intestinal volvulus involving the sigmoid colon 6. It is more common in the elderly 7.

Symptoms are that of a large bowel obstruction: constipation, abdominal bloating, nausea and/or vomiting. Onset may be acute or chronic.

There is a wide range of causes; some are geographically-specific 5:

  • chronic constipation and/or laxative abuse
  • fiber-rich diet (especially in Africa)
  • Chagas disease (especially in South America)

Sigmoid volvulus is differentiated from a cecal volvulus by its ahaustral wall and the lower end pointing to the pelvis.

Abdominal radiographs will show a large, dilated loop of the colon, often with a few gas-fluid levels. Specific signs include:

Although now uncommonly performed, a water-soluble contrast enema exquisitely demonstrates this condition, with the appearances described as the beak sign (or bird beak sign).

Endoscopic detorsion (e.g. rigid/flexible sigmoidoscopy, colonoscopy) in sigmoid volvulus cases without ischemia or perforation successfully treats ~80% (range 60-95%) of patients and is recommended as the initial treatment 8. Occasionally patients suffer from recurrent sigmoid volvulus, for which a surgeon may consider sigmoid colopexy (surgical fixation of the sigmoid colon), or in the surgically unfit, a percutaneous endoscopic colostomy (PEC) might be performed.

The mortality rate is 20-25% 7. The most serious complication is bowel ischemia.

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Article information

rID: 6398
Section: Signs, Radiography
Synonyms or Alternate Spellings:
  • Torsion of the sigmoid colon
  • Sigmoid colon volvulus

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Cases and figures

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  • Case 6: Frimann Dahl’s sign - sigmoid volvulus
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  • Case 11: on virtual colonoscopy
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  • Case 17: classic AXR appearances
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