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

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

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

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.

The pathophysiology of colonic volvulus is quite straightforward: the colon twists at least 180 degrees, resulting in closed-loop obstruction and occlusion of the vascular supply. Particularly in the case of sigmoid volvulus, the underlying mechanism of this twisting involves the presence of a large, floppy, redundant colon in combination with a long, narrow mesenteric base. This set of conditions, more common in elderly, infirm patients with constipation, accounts for the predominant involvement of the sigmoid colon. The relatively narrow mesentery provides a pivot point around which the heavy, mobile colon can rotate. In some cases, the colon may detorse spontaneously, and indeed, some patients report a history of similar symptoms at the time of presentation. However, the volvulus becomes problematic as it results in obstruction of the bowel lumen as well as occlusion of the arterial and venous blood supply, with a subsequent natural history of bowel gangrene, necrosis, and perforation.

Multiple underlying etiologies for this process have been proposed, all of which share the resulting pathogenesis of an enlarged, redundant colon that is prone to twisting. Chronic constipation and laxative use are likely the most common causes of sigmoid volvulus in the United States. However, a redundant colon can also contribute to the problem of constipation, making it difficult to ascertain the directionality of the causal relationship between these two processes. In other geographic areas, a high-fiber diet has been implicated, or possibly even genetic variation in colon and mesenteric length. In South America, Chagas disease is commonly an underlying cause of megacolon and subsequent volvulus. Hirschsprung disease is similarly associated with both a dilated colon and colonic volvulus.

In contrast to sigmoid volvulus, in which the chronic colonic elongation that predisposes to twisting is generally conceptualized as an acquired condition, the pathogenesis of cecal volvulus may in fact be more congenital in nature.⁵ While the same underlying situation of a floppy colon is necessary for cecal volvulus, this is more commonly seen in the setting of either prior mobilization of the right colon or congenital non-fixation of the cecum. This notion is further suggested by the differences in patient demographics that have been observed between cecal and sigmoid volvulus. As noted earlier, cecal volvulus patients tend to be much younger, more often female, and of thinner body habitus. These characteristics as well as intraoperative findings suggest that incomplete congenital fixation of the cecum plays a primary role in the pathogenesis of cecal volvuli.² Therefore, cecal and sigmoid volvulus should be thought of as distinct disease processes, affecting different patient populations and having different underlying etiologies.

Colonic volvulus can present as a partial or complete large bowel obstruction. Nonspecific signs and symptoms of acute bowel obstruction include nausea, vomiting, abdominal pain, distention, and constipation or obstipation. Sigmoid volvulus is often associated with significant abdominal distention, given the distal location of the obstruction, and obstipation. Cecal volvulus, in contrast, may present with less impressive distention and signs and symptoms consistent with distal small bowel obstruction. If the volvulus has progressed to gangrene and perforation of the involved colon, the patient may present with diffuse abdominal pain and tenderness consistent with peritonitis. Fever and leukocytosis are ominous signs suggestive of ongoing or impending bowel compromise.

The differential diagnosis for colonic volvulus includes other causes of mechanical and non-mechanical bowel obstruction, such as obstructing colon cancer, diverticular disease, and Ogilvie syndrome. These may be differentiated on the basis of acuity, associated signs and symptoms, and imaging. The patient may report a history of intermittent obstructive symptoms or chronic constipation, especially in the case of sigmoid volvulus.

The diagnosis of volvulus can often be made with plain radiographs alone. The classic “bent inner tube” or “coffee bean” sign on an anteroposterior abdominal radiograph is diagnostic of sigmoid volvulus in up to 80% of cases.⁶ With this finding, the “coffee bean” arises from the pelvis, and the cleft is classically oriented toward the left lower quadrant, pointing in the direction of the sigmoid colon (Fig. 44-1). Additional findings suggestive of closed loop obstruction include air−fluid levels on supine or decubitus images and absence or paucity of gas in the rectum, which can be particularly helpful in differentiating this diagnosis from pseudo-obstruction.⁶ The diagnosis of sigmoid volvulus can be confirmed with a contrast enema demonstrating a bird’s beak appearance (Fig. 44-2). While this imaging study may also be therapeutic in some cases, resulting in colonic detorsion, contrast enema should be avoided if there is concern for perforation or bowel compromise.