In a Foramen of Winslow hernia viscera enter the lesser sac through the foramen of Winslow. Usually this consists of small intestine but colon, omentum and the gallbladder may also enter.
Risk factors:
(1) enlarged foramen of Winslow
(2) unusually long small bowel mesentery
(3) elongated right liver
(4) persistence of the ascending mesocolon
(5) intestinal malrotation
(6) defect in the gastrohepatic ligament
(7) lack of fusion between the cecum or ascending mesocolon to parietal peritoneum
(8) common intestinal mesentery
Clinical features:
(1) small bowel obstruction
(2) gastric outlet obstruction
(3) progressive abdominal pain which is reduced by forward flexion
(4) obstructive jaundice
(5) strangulation of bowel with ischemia
CT findings:
(1) air-fluid level in the lesser sac
(2) bird beak sign
(3) absence of the cecum and ascending colon in the right gutter
(4) loops of bowel in the high sub-hepatic space
(5) mesenteric vessels are stretched, posterior to the main portal vein and anterior to the inferior vena cava
