Diagnostic modalities imaging of sigmoid volvulus in adults

In adults, large bowel obstruction is predominantly attributed to colon or rectal cancer, diverticular disease, or colonic volvulus. Obstruction from the colonic volvulus results from twisting a redundant segment of the colon on its mesentery. Volvulus predominantly occurs in the sigmoid colon or cecum in over 95% of cases, with the remainder involving either the transverse colon or splenic flexure. The diagnosis of volvulus is established through clinical evaluation and imaging modalities. Abdominal plain x-rays are usually diagnostic with a coffee bean appearance showing a massive distended sigmoid colon, providing diagnostic clarity in 50% to 75% of cases. Nevertheless, the diagnostic efficacy of abdominal computerized tomography (CT) and magnetic resonance imaging (MRI) is typically claimed to exceed 90%. In CT and MRI, the characteristic finding of sigmoid volvulus is the mesenteric whirl sign, resulting from a rotating sigmoid mesentery, together with a dilated sigmoid colon and air-fluid levels in the small intestine. The diagnostic accuracy of CT and MRI was 97.3% and 95.6% respectively.