A Case of Non-obstetric Ovarian Vein Thrombosis Associated With Acute Pyelonephritis Presenting to the Emergency Department.

Ovarian vein thrombosis (OVT) is a rare type of venous thromboembolism (VTE) that is most often reported during the postpartum period and is rarely seen outside pregnancy. In non-obstetric settings, its presentation is often nonspecific and may resemble more common urinary, gastrointestinal, or gynecologic emergencies. It may also be missed on contrast-enhanced abdominopelvic CT, particularly when CT interpretation is biased toward a more common diagnosis. We report the case of a 36-year-old woman who presented to the emergency department (ED) with sudden-onset abdominal and pelvic pain, urinary symptoms, and significant systemic inflammation. Initial contrast-enhanced CT was interpreted as left-sided acute pyelonephritis, and antibiotic therapy was started. On day three, a subsequent review of the same CT examination by an attending radiologist identified an extensive left-sided OVT that had been missed on the preliminary on-call CT report, and the patient was recalled to the ED for initiation of therapeutic anticoagulation. Rivaroxaban was prescribed for three months, with a good clinical course. This report highlights non-obstetric OVT as an uncommon but important differential diagnosis in women with acute abdominal or pelvic pain that may closely resemble urinary, gastrointestinal, or gynecologic emergencies. A systematic evaluation of the ovarian and other abdominopelvic veins on contrast-enhanced CT, with additional review by an attending radiologist when appropriate, may help reduce the risk of missed diagnoses.