Tehran University of Medical Sciences (TUMS) Academic Journal of Surgery 2423-3218 8 3 2025 12 22 81 85 Sepideh Aarabi Department of Emergency Medicine, Sina hospital, Tehran University of Medical Sciences, Tehran, Iran 2025 08 12 Warfarin remains a cornerstone anticoagulant therapy for patients with mechanical heart valves but carries significant bleeding risks. Ovarian hemorrhagic cysts represent a rare but potentially life-threatening complication in women of reproductive age receiving anticoagulation therapy. The combination of warfarin overdose and ovarian bleeding can result in severe hemoperitoneum requiring emergency intervention. I present the case of a 48-year-old woman with a history of mitral valve replacement who was admitted to the emergency department with acute pelvic pain. The patient had been receiving warfarin therapy for mechanical valve anticoagulation and developed signs of warfarin overdose with an International Normalized Ratio of 8.9. Computed tomography revealed a large hemorrhagic ovarian cyst with associated hemoperitoneum. Conservative management was initially attempted with warfarin reversal using prothrombin complex concentrate. However, due to hemodynamic instability, the patient required emergency laparotomy. Right salpingo-oophorectomy was performed. The patient recovered fully and was discharged on postoperative day 9. Emergency physicians and surgeons should maintain high clinical suspicion for ovarian hemorrhagic complications in women of reproductive age receiving anticoagulation therapy, particularly when presenting with acute pelvic pain, oliguria, and elevated coagulation parameters. Early recognition, appropriate reversal of anticoagulation, and timely surgical intervention when indicated can prevent life-threatening complications and preserve reproductive function. https://ajs.tums.ac.ir/index.php/ajs/article/view/320