Omental torsion is defined as a twist of the omentum along its long axis with consequent impeding of its vascularity that may mimic acute abdomen 1.
Omental torsion is a rare cause of acute abdominal pain that occurs in the third to fifth decade of life with slight male predominance 2.
Sudden right lower quadrant or right paraumbilical abdominal pain that mimics acute appendicitis. The pain is persistent and non-radiating with increasing severity. Nausea and vomiting may also be a feature.
An abdominal palpable mass lesion may be detected in 50% of the patient 3.
Primary omental torsion
No identifiable cause but may be related to local omental anatomical variations that allow a movable segment of omentum to twist around the proximal fixed point 4:
- bifid omentum
- accessory omentum
- bulky omentum
- redundant omentum
- redundancy of omental veins that lead to kink in the associated shorter arteries
Secondary omental torsion
More frequent than primary omental torsion. It occurs secondary to hernial sacs, surgical scars or wounds, tumours and cysts. Inguinal hernias are the most common cause of secondary omental torsion.
Any movement that may result in the sudden increase of intra-abdominal pressure or vigorous propulsive movements, e.g. exercise, coughing, sneezing, trauma.
Complex solid and hypoechoic components. In addition to free fluid in the peritoneal cavity may be detected.
CT is the main diagnostic tool and may show 5
- fat density lesion in the right paraumbilical or right lower quadrant
- streaks of whirling and concentric pattern (whirl sign)
- whirling pattern may not be visualized if the axis of rotation is not perpendicular to the transverse scanning plane 1
- free fluid may be detected in the peritoneal cavity
Treatment and prognosis
Laparoscopy can identify and remove the infarcted part of the omentum, as well assess for other probable pathologies, such as appendicitis or acute cholecystitis
The condition is self-limited in most cases. Treatment of the cause of secondary types is necessary.
If omental torsion is untreated, spontaneous detorsion may occur and may result in adhesion seen in the right lower abdominal quadrant incidentally during any surgery.
- vascular compromise and progression to omental infarction (necrosis) distal to the point of twist later adhesive formation
- adhesive bowel obstruction
- sepsis / abscess formation
Omental torsion must be considered as a differential consideration of the patient with an acute abdomen:
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- 2. Tsironis A, Zikos N, Bali C, Pappas-Gogos G, Koulas S, Katsamakis N: Primary Torsion of the Greater Omentum: Report of Two Cases and Review of the Literature. The Internet Journal of Surgery 2008., 17(2)
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- 4. Karayiannakis AJ, Polychronidis A, Chatzigianni E et-al. Primary torsion of the greater omentum: report of a case. Surg. Today. 2002;32 (10): 913-5. doi:10.1007/s005950200180 - Pubmed citation
- 6. Tandon AA, Lim KS. Torsion of the greater omentum: A rare preoperative diagnosis. Indian J Radiol Imaging. 2010;20 (4): 294-6. doi:10.4103/0971-3026.73540 - Free text at pubmed - Pubmed citation
- Kim J, Kim Y, Cho OK et-al. Omental torsion: CT features. Abdom Imaging. 2004;29 (4): 502-4. doi:10.1007/s00261-003-0155-2 - Pubmed citation