Volvulus refers to torsion of a segment of the alimentary tract, which often leads to bowel obstruction. The most common sites of volvulus are the sigmoid colon and cecum. Volvulus of other portions of the alimentary tract, such as the stomach, gallbladder, small bowel, splenic flexure, and transverse colon, are rare.
The diagnosis and treatment of sigmoid volvulus will be reviewed here. Cecal volvulus is discussed separately. (See "Cecal volvulus".)
Volvulus of the sigmoid colon represents approximately 40 to 70 percent of colonic volvulus depending upon the age of patients and the geographic location of the series (picture 1) [1-4]. In one series of 137 patients with colonic volvulus, the following colonic segments were involved :
- Cecum – 52 percent
- Sigmoid – 43 percent
- Transverse colon – 3 percent
- Splenic flexure – 2 percent
The precise incidence of sigmoid volvulus in the population is not well-established, and its prevalence among patients who present with acute intestinal obstruction varies geographically. In the United States, sigmoid volvulus is a relatively uncommon cause of intestinal obstruction representing fewer than 10 percent of cases in most series . In contrast, for unclear reasons, the prevalence is much higher in other parts of the world [5-8]. As an example, sigmoid volvulus was responsible in 80 percent of cases of intestinal obstruction from the Bolivian and Peruvian Andes , and 50 percent of cases of large bowel obstruction in Nigeria . The incidence may also be increased in Brazil, where it may be a complication of megacolon caused by Chagas disease . (See "Pathology and pathogenesis of Chagas disease".)