Omental infarction (OI) is a condition where the greater omentum is subjected to ischemic damage due to interrupted blood flow. It is rare and often characterized by right lower quadrant abdominal pain [1]. One in one thousand laparotomies performed is secondary to acute abdomen arising from OI.

OI can be classified into primary and secondary [2]. In primary disease, the exact pathogenesis is unknown. There is a greater incidence of OI on the right hand side, and literature suggests that the reason lies in abnormal vasculature, stemming from embryonic factors, making it particularly vulnerable to congestion and decreased blood flow [3]. This is often referred to as primary idiopathic segmental OI [4]. In some cases the omentum first twists around itself, which then leads to OI. Conditions that predispose to omental torsion are obesity, adhesions, increased peristalsis, intra abdominal masses, and increased abdominal pressure [5]. Obesity is thought to increase the risk of torsion because of the additional fat tissue that disrupts the arterial blood supply and increases the weight of the omentum [6]. Males are more affected by idiopathic OI than females. OI has been known to occur in children as well, notably those who are obese. Secondary OI results from various medical conditions such as trauma, surgery, vascular disease and hypercoagulable states.

Because of its uncommon occurrence and non specific presentation, OI is frequently misdiagnosed, as clinicians suspect more common causes of acute abdomen, namely appendicitis, acute cholecystitis, peptic ulcer disease and so on [7]. Constitutional symptoms such as fever, as well as gastrointestinal upset (nausea, vomiting, diarrhea) are usually absent. Right sided guarding may be elicited [3].

• Left Flank Pain

  A 75-year-old woman presented with acute lower abdominal and left flank pain with rebound tenderness. [ncbi.nlm.nih.gov]

• Peritoneal Disease

  Surgery Volume 75, Issue 4 （April 2013） 臨床雑誌外科 75巻4号 （2013年4月） CTで術前診断し腹腔鏡下に手術しえた特発性分節性大網梗塞の1例 御井 保彦 1, 阿部 紘一郎, 宗實 孝, 有川 俊治, 高橋 洋 1 三木市立三木市民病院 外科 キーワード： 梗塞, 術前診断, 腹腔鏡法, 腹膜疾患, 網, 腹部CT Keyword: Infarction, Omentum, Peritoneal Diseases, Laparoscopy pp.404 [webview.isho.jp]

• Abdominal Fullness

  Physical examination revealed epigastric and right upper abdominal fullness, and laboratory studies showed elevated erythrocyte sedimentation rates, with normal leukocyte counts and coagulation profiles. [ncbi.nlm.nih.gov]

• Abdominal Rigidity

  On physical examination, the patient was febrile with a temperature of 38.1 C and had severe left lower quadrant tenderness and abdominal rigidity. [onlinejets.org]

• Epigastric Tenderness

  Clinical examination revealed epigastric tenderness without peritoneal irritation. Blood analysis showed moderate leucocytosis and strongly elevated CRP. No fever was present. [eurorad.org]

• Protein S Deficiency

  Omental gangrene and porto-mesenteric thrombosis in a patient of protein C and protein s deficiency. Indian J Surg 2013;75 Suppl 1:409-11. 10. Park KE, Chung DJ, Kim W, Hahn ST, Lee JM. [jmgims.co.in]

• Microscopic Hematuria

  Routine investigations showed leucocytosis and microscopic hematuria in urinalysis. He was put on antibiotics and analgesics, recovered in 2 days and discharged since he was not willing for surgery. [saudisurgj.org]

As the clinical picture is unreliable in diagnosis, more emphasis has been placed on imaging modalities. Because of their improved availability, accuracy, and thus detection rate, fewer exploratory laparotomies are being done [2] [8]. Furthermore, this may explain the apparent increased incidence of omental infarction, added to more awareness of the condition by physicians [9]. Radiology is thus paramount, as it confirms the diagnosis and influences management.

In primary omental OI, abnormalities are likely to be present in the right lower quadrant, whereas secondary OI mostly appears at the site of the causative injury. The distinction between idiopathic omental infarction, and infarction secondary to torsion can only be definitively made intra-operatively.

Imaging:

• Abdominal ultrasound: This may show a focused hyper-echoic accumulation of fat that is not compressible.
• Computerized tomography (CT): This may show a well demarcated lesion with fat stranding, between the anterior abdominal wall and the bowel [10]. Omental torsion may be indicated by twisted blood vessels, which is known as the swirl sign [8]. The whole lesion may have a hyperdense rim around it. Pelvic and abdominal CT scanning is the imaging modality of choice [11].

• Hemorrhagic Ascites

  Primary omental leiomyosarcoma masquerading as hemorrhagic ascites. Hum Pathol. 1984; 15 :233-237. 9. Wagner JC, Sleggs CA, Marchand P. Diffuse pleural mesothelioma and asbestos exposure in the North Western Cape Province. [wjgnet.com]

• Fibrinoid Necrosis

  Final pathological examination revealed hemorrhagic infiltrations, thrombosis of the tissue, acute inflammatory cellular infiltrate, and fibrinoid necrosis, and POI was diagnosed [Figure 3]. [onlinejets.org]

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