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DEFINITION/INTRODUCTION
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Colonic volvulus refers to the twisting of the colon around its mesenteric axis. Although an uncommon cause of large bowel obstruction in the United States, it is a potentially life-threatening condition that necessitates expedient surgical evaluation and treatment. The twisting of the colon results in a closed-loop obstruction, occlusion of the mesenteric vessels, and subsequent ischemia of the affected segment of bowel. Volvulus can affect any part of the bowel, and is classified based on the segment of colon involved. Given its redundancy and relatively long, narrowly-based mesentery, the sigmoid colon is the most common site of colonic volvulus, followed in frequency by the cecum. Other much rarer forms of colonic volvulus include cecal bascule, transverse colonic volvulus, ileosigmoid knotting, and splenic flexure volvulus. Sigmoid volvulus accounts for up to 80% of all colonic volvuli, while the cecum appears to be involved in approximately 20% of cases.1,2
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In the United States, it is estimated that colonic volvulus accounts for less than 5% of all large bowel obstructions (LBOs), making it the third most common cause of LBO after cancer and diverticular disease in adult patients.1–4 Interestingly, dramatic international geographic variation in the incidence of this disease process has been observed. In some countries, including Pakistan, India, and Brazil, sigmoid volvulus alone has been reported to account for 20% to 30% of all intestinal obstructions and is implicated in over 54% of obstructions in Ethiopia.1 It has long been known that colonic volvulus has a much higher incidence in parts of Africa, the Middle East, and South America. It has been postulated that this variability is related to the very-high-fiber diets common in these regions leading to colonic redundancy, as well as Chagas disease−related megacolon in South America.1
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Not only is there geographic variability in the incidence of colonic volvulus, but also in the demographics of the populations most commonly affected. In the United States and other Western developed nations, the stereotypical demographic of the patient presenting with sigmoid volvulus is an elderly, chronically ill, institutionalized patient with a history of chronic constipation. In addition, there seems to be an association with neuropsychiatric disorders such as Parkinson disease and dementia. However, these comorbidities do not necessarily correlate with volvulus in areas where colonic volvulus is a more endemic phenomenon.2
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While sigmoid volvulus occurs in similar proportions of men and women, with perhaps a slight male bias, cecal volvulus has a clear female predominance. Cecal volvulus also tends to affect younger patients, with a mean age of diagnosis around the fourth or fifth decade of life. Table 44-1 highlights some of the key differences between sigmoid and cecal volvulus.
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