Presumed idiopathic omental hemorrhage mimicking complicated appendicitis: a rare case report.

INTRODUCTION AND IMPORTANCE: Acute abdominal pain is a common cause of emergency department visits. Massive presumed idiopathic omental hemorrhage (IOH) is an extremely rare condition that may clinically and radiologically resemble complicated appendicitis or malignancy and may require urgent operative exploration despite misleading initial imaging. CASE PRESENTATION: A 48-year-old obese male with prediabetes presented with sudden-onset abdominal pain that was initially located in the epigastric region, then migrated to the right lower quadrant. Clinical examination and sonography suggested complicated appendicitis. A CT scan showed a mass-like lesion in the right lower quadrant, along with free intraperitoneal fluid, raising suspicion for malignancy or complicated appendicitis. An exploratory laparotomy was performed and revealed 2.5 liters of hemoperitoneum and active bleeding from the greater omentum with a normal appendix. Ligation of the bleeding vessel with partial omentectomy was performed. The WBC count dropped from 19.5 × 103/µL preoperatively to 11.5 × 103/µL at discharge. The patient was stable and discharged a few days after the operation. CLINICAL DISCUSSION: IOH is a rare and life-threatening condition that can mimic the clinical features of common causes of acute abdomen. IOH can be the result of a congenital vascular malformation, spontaneous rupture of fragile omental vessels, or intermittent omental torsion. In our case, the imaging findings were misleading and initially reported as complicated appendicitis. Early surgical intervention remains the cornerstone of the diagnosis and treatment of IOH, as delaying proper management can put the patient's life at risk. CONCLUSION: Although IOH is rare, it should be considered in patients presenting with an acute abdomen and atypical imaging findings. Increased awareness among surgeons can facilitate prompt intervention and improve outcomes.