Clockwise whirlpool sign at color Doppler US: an objective and definite sign of midgut volvulus.

PURPOSE: To evaluate the clockwise whirlpool sign at color Doppler ultrasound (US) in the diagnosis of midgut volvulus.

MATERIALS AND METHODS: Pediatric patients (160 boys, 76 girls; age range, 0 day to 14 years) with possible midgut volvulus underwent abdominal gray-scale US and color Doppler US. Midgut volvulus was diagnosed by recognition of the whirlpool sign (wrapping of the superior mesenteric vein and the mesentery around the superior mesenteric artery). If the whirlpool rotated clockwise with caudal movement of the transducer, the direction of the whirlpool was defined as clockwise.

RESULTS: Color Doppler US showed a whirlpool sign that was clockwise in 12 of 13 patients with surgically confirmed midgut volvulus and counterclockwise in three patients without midgut volvulus. Sensitivity, specificity, and positive predictive value of clockwise whirlpool sign for midgut volvulus were 92%, 100%, and 100%.

CONCLUSION: The clockwise whirlpool sign is diagnostic of midgut volvulus. Color Doppler US should be performed as an initial imaging study in children suspected of having midgut volvulus.