An 82-Year-Old Woman With Abdominal Pain

James J. McCombie, MB ChB

Disclosures

March 13, 2017

Discussion

This patient was diagnosed with sigmoid volvulus. Volvulus is a rotation of part of the intestine around an axis somewhat perpendicular to the line of its mesentery, resulting in partial or complete obstruction of the lumen. If not relieved, the condition can lead to bowel ischemia, gangrene, and perforation, often with significant mortality.

In general, volvulus is responsible for 1%-7% of large-bowel obstructions.[1] In a series of large-bowel volvulus cases, the sigmoid was involved in 76% of patients, the cecum in 22%, and the transverse colon in 2%.[2] Volvulus of the splenic flexure accounts for 1% of cases.[3] Because volvulus involves twisting around a pedicle formed by the mesentery, a sigmoid mesocolon that is vertically longer (from its root) than it is wide is frequently cited as a predisposing factor.[4]

Rotation leading to clinical symptoms is generally between 180° and 720°, in either a clockwise or counterclockwise direction. Lesser degrees of rotation may produce either no symptoms or transient and spontaneously resolving abdominal pain. Rotation of 360° or more generally leads to strangulation and/or obstruction.

The incidence of sigmoid volvulus is not well established. It is a relatively uncommon cause of intestinal obstruction, generally accounting for < 10% of cases in most series.[5,6] More than 50% of patients are older than 70 years. Many patients have neuropsychiatric illness or are bedridden and have chronic constipation. A high-residue and low-fiber Western diet is implicated in the genesis of chronic constipation and provides an educational and therapeutic target to reduce the incidence of constipation and subsequent volvulus.[7,8]

Sigmoid volvulus also occurs as a complication of megacolon, and this association is particularly identified in areas where Chagas disease is endemic, such as Brazil.[9] Another interesting association is that volvulus (sigmoid more often than cecal) accounts for 25% of cases of intestinal obstruction in pregnancy, occurring more frequently in the third trimester, perhaps as a result of uterine displacement of the colon.

Typical presentations of sigmoid volvulus may include some or all of the following: colicky abdominal pain (often with persistence of pain between spasms), constipation, obstipation, and subjective complaints of abdominal bloating or fullness. Examination frequently reveals massive distention (that is often asymmetric) and generalized tympany.

Severe pain, focal tenderness, peritoneal signs, tachycardia, and hypotension should raise the possibility of strangulation, necrosis, or perforation. In addition, an elevated white blood cell count and high anion gap metabolic acidosis with increased lactate levels also suggest intra-abdominal complications, as identified above. The medical history often includes previous episodes of nonadhesive colonic obstruction as well as fecal impaction, which is reported in 40%-60% of cases.[10]

A plain radiograph of the abdomen is often diagnostic and typically reveals a greatly distended loop of large bowel that has lost its haustral markings. This loop rises out of the pelvis towards the transverse colon. A distinct vertical crease is often present, which results from apposition of the walls of adjacent dilated bowel and can be traced downward to the point of torsion. This has been called the "coffee bean" sign. Rectal gas is usually absent. If a barium enema is performed, the contrast column tapers at the site of obstruction, forming an "ace of spades" or "bird's beak" appearance.

CT confirms the distended loop of sigmoid colon, possibly demonstrating a "whirl sign," in which the afferent and efferent loops of bowel are rotated around a tightly twisted mesentery. In addition, there are two transition points in sigmoid volvulus, and both of these transition points can sometimes be detected with CT. In these cases, the transition points are typically in proximity and oriented in opposite directions.[11]

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