Sigmoid volvulus
Updates to Article Attributes
Sigmoid volvulus is a cause of large bowel obstruction and occurs when the sigmoid colon tortes on the sigmoid mesocolon.
Epidemiology
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.
Clinical presentation
Symptoms are that of a large bowel obstruction - constipation, abdominal bloating, nausea and/or vomiting. Onset may be acute or chronic.
Pathology
Aetiology
There is a wide range of causes, some are region-specific 5:
- chronic constipation and/or laxative abuse
- fibre-rich diet (especially in Africa)
- Chagas disease (especially in South America)
Associations
- chronic neurological conditions (e.g. Parkinson disease, multiple sclerosis, pseudobulbar palsy)
- chronic psychiatric conditions (e.g. chronic schizophrenia)
Radiographic features
Sigmoid volvulus is differentiated from a caecal volvulus by its ahaustral wall and the lower end pointing to pelvis.
Plain film
Abdominal radiographs will demonstrated a large, dilated loop of colon, often with a few air-fluid levels. Specific signs include:
- coffee bean sign 5
- Frimann Dahl's sign - three dense lines converge towards site of obstruction
- absent rectal gas 5
Fluoroscopy
Although now uncommonly performed, a water soluble contrast enema exquisitely demonstrates this condition, with the appearances described as the bird of prey sign.
CT
- large gas-filled loop without haustral markings, forming a closed-loop obstruction 6, 7
- whirl sign - twisting of the mesentery and mesenteric vessels
- beak sign - if rectal contrast has been administered 6
Treatment and prognosis
Rectal tube insertion is successful in successful in treating 90% of cases 5. Mortality rate is 20-25% 7. The most serious complication is bowel ischaemia.
Differential diagnosis
- large bowel obstruction from other causes
- caecal volvulus
- colonic pseudo-obstruction
-</ul><h4>Treatment and prognosis</h4><p>Rectal tube insertion is successful in successful in treating 90% of cases <sup>5</sup>. Mortality rate is 20-25% <sup>7</sup>. </p><h4>Differential diagnosis</h4><ul>- +</ul><h4>Treatment and prognosis</h4><p>Rectal tube insertion is successful in successful in treating 90% of cases <sup>5</sup>. Mortality rate is 20-25% <sup>7</sup>. The most serious complication is <a title="Bowel ischaemia" href="/articles/intestinal-ischaemia">bowel ischaemia</a>.</p><h4>Differential diagnosis</h4><ul>