Case Of the Week (COW) 31 January 2016

SIGMOID VOLVULUS

Findings
There is disproportion significant dilatation of sigmoid colon and coffee bean sign. The loop is not extending cephalad to the transverse colon OR overlap liver shadow. Seperation of two loops of colon by mesenteric fat noted – SPLIT WALL SIGN. Twist of the colon distal to the dilatation (whirl sign) noted. Rectum is partially distended. There is no mass or lymphadenopathy seen in the retro peritoneum. No free fluid is seen in the peritoneal cavity. No evidence of Pneumoperitoneum.
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Discussion
Sigmoid volvulus is abnormal twisting of the sigmoid colon along its mesenteric axis that causes closed-loop obstruction and can lead to ischemia, perforation, and death. Marked distention of an ahaustral sigmoid colon that assumes a coffee bean– like configuration. The loop, which is classically described as pointing to the right upper quadrant, also can rise to the level of the left hemidiaphragm and overlap the liver shadow A more recently described specific feature of volvulus is cephalic extension of the sigmoid in relation to the transverse colon (the northern exposure sign).

EF; CT Findings of Sigmoid Volvulus AJR 2010; 194:136–143