We report a case of duodenal malrotation that presented in adulthood as midgut volvulus. On colour Doppler ultrasound, findings of a clockwise rotation of the superior mesenteric vein around the superior mesenteric artery (whirlpool sign) and a distinctive 'whirl'-like pattern resulting from an encircling of loops of the bowel around the SMA on CT is diagnostic of midgut volvulus.
Puvaneswary, M., & Rajaratnam, S. (2003). Midgut volvulus in an adult. Australasian Radiology, 47(1), 83–84. https://doi.org/10.1046/j.1440-1673.2003.01112.x