Sigmoid Volvulus: Diagnostic Modalities and Sigmoid Gangrene.

In SV, abdominal pain/tenderness, obstipation, and asymmetrical abdominal distention (Figure 1a), which are described as the volvulus triad, are observed in 52%-99% of patients.1,3 In our evaluation, these clinical features were found in 98.9%, 96.6%, and 92.4% of patients, respectively. Other clinical features are vomiting, hyperkinetic or hypokinetic bowel sounds, empty rectum or melanotic stool, and shock.1,3 In endemic regions, the determination of the abovementioned features in a middle aged or elderly man is generally suggestive of SV.3 Plain abdominal X-ray radiography demonstrating an omega-shaped sigmoid colon with small intestinal air-fluid levels is diagnostic in 25%-90% of patients (Figure 1b)1,3; this was observed in 68.2% of our patients. Nevertheless, the diagnostic values of computerized tomography (CT) and magnetic resonance imaging (MRI) are generally reported to be over 90%. In CT and MRI, the pathognomonic finding of SV is mesenteric whirl sign arising from rotated sigmoid mesentery in addition to the dilated sigmoid colon and small intestinal air-fluid levels (Figures 1c, 1d).3 In our evaluation, the diagnostic accuracy of CT and MRI were 97.3% and 95.6%, respectively. Endoscopic sign of SV is a spiral torsion of the lumen, usually 20-30 cm from the anal verge (Figure 1e). Endoscopy is diagnostic in 76%-100% of patients3; this was observed in 98.7% of our patients. When CT, MRI, or endoscopy are not used, SV is easily misdiagnosed as an intestinal obstruction, which generally requires an emergency laparotomy.1,3