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Sigmoid volvulus occurs when the last part of the colon twists on itself, causing obstruction and compromising the blood supply to the colon.
The sigmoid colon is an S-shaped part of the colon that is in the left lower side of the abdomen, above the rectum. With age, this part of the colon or its attachments to the abdominal wall stretch out, allowing it to twist on itself, similar to the twisting of a long balloon, resulting in a volvulus. When this happens, the colon becomes blocked. In addition, the blood supply may be reduced, leading to injury or death of the tissues of that part of the colon. If not treated quickly, this can result in a perforation, a hole in the bowel through which stool and gas can spill into the abdomen. Perforations can be fatal without urgent intervention. Older age, chronic constipation, and living in a nursing home increase the risk of having sigmoid volvulus.
Patients commonly experience one or several days of lower abdominal pain, bloating, constipation, lack of passing gas, and sometimes nausea and vomiting. Because the sigmoid colon is twisted on itself, stool and gas cannot pass beyond it and the bowel becomes obstructed. The physical examination and history for a patient with a swollen tender abdomen and constipation may indicate sigmoid volvulus. Laboratory test results may be normal or show signs of infection if the blood supply to the sigmoid colon is compromised. An abdominal x-ray scan may show a large dilated colon or air within the abdomen outside the intestine if there is perforation. A computed tomography scan or a contrast enema through the rectum may also be used to confirm the diagnosis.
Sigmoid volvulus is considered a medical emergency and should prompt immediate treatment. If the colon is twisted and the blood supply is intact, then a colonoscopy may be performed to untwist the colon. This usually resolves the blockage quickly. However, this is only a temporary solution because the risk of the sigmoid twisting on itself again is high. Patients who are successfully treated with a colonoscopy should undergo elective surgery to remove the sigmoid colon during the same hospital stay. This can usually be done without need for a colostomy (a surgical opening to divert the intestine). If the colon has been without adequate blood flow for too long or perforation of the bowel has occurred, then the patient should undergo emergency surgery to remove the sigmoid colon. In these situations, the risk of needing to have a colostomy is higher. Similarly, a history of previous surgeries, overall health and nutrition, or other patient factors may also increase the risk of needing to have a colostomy. There are no means to prevent sigmoid volvulus, and prophylactic surgery is not recommended.
Conflict of Interest Disclosures: None reported.
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Oren D, Atamanalp SS, Aydinli B, et al. An algorithm for the management of sigmoid colon volvulus and the safety of primary resection: experience with 827 cases. Dis Colon Rectum. 2007;50(4):489-497.
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