Rotation of sigmoid volvulus occurs

In sigmoid volvulus, * Always rotation is anticlockwise. * It requires one and half turn of rotation to cause vascular obstruction and gangrene which eventually leads into perforation either at the root or at the summit of the sigmoid loop. * Enormous distension of the colon occurs. Sometimes ileum comes to the root of the sigmoid volvulus and encircles it causing compound volvulus in which case knotted small bowel also becomes gangrenous. -ileosigmoid knotting. ref:SRB 's manual of surgery,ed 5,pg no- 931