Omental infarction is a rare cause of acute abdomen resulting from vascular compromise of the greater omentum. This condition has a non-specific clinical presentation and is usually managed conservatively. The term along with epiploic appendagitis is grouped under the broader umbrella term intraperitoneal focal fat infarction 9.
Patients may present with 1:
- sudden onset of abdominal pain
- right lower quadrant pain and tenderness
- absence of fever and gastrointestinal symptoms
- encountered in healthy patients, such as marathoners, because of low omental blood flow
Primary omental infarction
The classic location of primary omental infarction is in the right lower quadrant. The vascular compromise occurs along the right edge of the greater omentum where the arterial supply is usually tenuous.
Sometimes it is the result from kinking of venous channels in the inferior part of the greater omentum in the pelvis. Occasionally omentum twists on itself resulting in omental torsion leading to both arterial and venous compromise. The omentum may infarct without torsion, and this is called as primary idiopathic segmental infarction 8.
Secondary omental infarction
- post surgery
- abdominal trauma
- omental inflammation
Primary omental infarction is usually seen in the right lower quadrant. Secondary omental infarction is located at the site of initial insult. It is usually larger than 5 cm, which helps distinguishing it from epiploic appendagitis 1.
- focal area of increased echogenicity in the omental fat
- focal area of fat stranding
- swirling of omental vessels in omental torsion
- hyperdense peripheral halo
Treatment and prognosis
This condition is often self-limiting and can be managed conservatively. Occasionally complications such as abscess formation occur which require surgery or radiological drainage.
General imaging differential considerations include:
- usually smaller areas of fat stranding compared to the omental infarction
- ovoid central area of preserved fat
- hyperdense central dot (thrombosed vessel)
- more a clinical differential, as the appendix should be identified inflamed
- fat stranding surrounding a colonic diverticulum
- when differentiating from the omentum, remember that the mesenterium always has a bowel loop at its end
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