Omental infarction is one of the diseased included under the term intraperitoneal focal fat infarction  and is a rare cause of acute abdomen resulting from compromise of the vascular structures of the greater omentum.
The greater omentum is a double layer of peritoneum that extends inferiorly from the greater curvature of the stomach, turns superiorly on itself to drape over the transverse colon, and extends to the retroperitoneal pancreas. Its blood its supplied by both right and left gastroepiploic arteries.
This disease has a non-specific clinical presentation, with signs and symptoms that comprise acute abdominal pain, right lower quadrant pain and tenderness, and abscence of fever. It may be either primary; more frequent in the right lower quadrant, as a result of a mechanical or haemodynamic compromise; or secondary, particularly to surgery, abdominal trauma or inflammation of the omentum. The secondary form normally presents at the site of initial insult.
The greater omentum appears on CT as a band of fatty tissue that contains small vessels and is located just anterior to the transverse colon. It has a variable thickness, which depends primarily on the weight of the individual. Segmental omental infarction typically occurs on the right (mimicking appendicitis or gallbladder disease), a predilection that has been attributed to an embryologic variant of the blood supply of the right portion of the omentum, which predisposes it to venous thrombosis
Reactive bowel wall thickening may occur, but the inflammatory process in the omentum usually is disproportionately more severe.
Useful procedures for the diagnosis of omental infarction include ultrasound (US) and computed tomography (CT). The characteristic finding on the former is a focal area of hyperechogenicity in the omental fat. On the latter, the findings comprise a focal area of fat stranding, which may vary in size; a peripheral halo of increased attenuation; and, in cases where there is a mechanical cause, a swirling of the omental vessels (whirlpool sign).
The main differentials are epiploic appendagitis, which is more usual on the left side and is usually smaller than 5 cm, and mesenteric panniculitis, which is commonly originated in the mesenteric root.
Omental infarction is often self-limiting and can be managed conservatively. If complications such as an abscess occur, surgery or radiological drainage is needed.