Omental torsion

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.

Epidemiology

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.

Clinical presentation

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. A palpable abdominal mass may be detected in 50% of patients ³.

Pathology

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, tumors and cysts. Inguinal hernias are the most common cause of secondary omental torsion.

Risk factors

Any movement that may result in the sudden increase of intra-abdominal pressure or vigorous propulsive movements, e.g. exercise, coughing, sneezing, trauma. 

Radiographic features

Ultrasound

Complex solid and hypoechoic components. In addition to free fluid in the peritoneal cavity may be detected.

CT

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.

Complications

• vascular compromise and progression to omental infarction (necrosis) distal to the point of twist later adhesive formation

• peritonitis

• adhesive bowel obstruction

• sepsis or abscess formation

History and etymology

The first description of omental torsion occurred in 1899 by Eitel ⁸.

Differential diagnosis

Omental torsion must be considered as a differential consideration of the patient with an acute abdomen:

• acute appendicitis

• acute cholecystitis

• ovarian torsion

• perforated diverticulum

• mesenteric lymphadenitis

• mesenteric panniculitis

• epiploic appendagitis

• omental infarct: the omentum may infarct without any torsion which is considered as primary idiopathic segmental infarct