Patient selection: history of Roux-en Y anastomosis
Risk factors:
(1) retrocolic procedure
(2) rapid weight loss with reduction in adipose tissue
(3) laparoscopic procedure
Types:
(1) transmesocolic: bowel loops herniate through the surgical defect in the transverse mesocolon
(2) jejunostomy mesenteric: bowel prolapse through a defect in the small bowel mesentery
(3) Petersen type: bowel loops protrude behind the Roux loop before the small bowel eventually passes through the defect in the transverse mesocolon in the Petersen defect (space located between the jejunal mesentery of the Roux limb and transverse mesocolon)
Clinical findings:
(1) small bowel obstruction, often without vomiting
(2) palpable abdominal mass
(3) volvulus with ischemia
CT findings:
(1) swirled mesentery
(2) small bowel obstruction
(3) hurricane eye (distal tubular mesentery with surrounding small bowel loops)
(4) beaking of superior mesenteric vein (decreased caliber with beaked appearance)
(5) criss cross appearance of second order mesenteric vessels (reversal of the anatomic relationship of the superior mesenteric artery and vein)
(6) mushroom sign (mushroom-shaped mesenteric root between the superior mesenteric artery and the distal mesenteric arterial branch)
(7) small bowel behind superior mesenteric artery
(8) weeping mesentery (edematous mesentery with enlarged lymph nodes)
(9) right-sided anastomosis
