A rare twist in ohvira syndrome: When menstrual blood takes an unusual route: A case report.

Obstructed Hemivagina and Ipsilateral Renal Anomaly (OHVIRA) syndrome is a rare congenital Müllerian anomaly comprising uterus didelphys, obstructed hemivagina, and ipsilateral renal agenesis. A 20-year-old female presented with cyclical perianal bleeding and severe dysmenorrhea. Initial ultrasound revealed a large tubular cystic pelvic lesion with internal echoes, initially misinterpreted as a dilated ectopic ureter or adnexal mass, especially in the context of absent left kidney. A separate normal uterus was also visualized. On repeat ultrasound during menstruation, the lesion had decompressed via a fistulous tract opening near the perianal region, allowing recognition of the structure as a second uterine horn. MRI confirmed uterus didelphys, obstructed left hemivagina with hematometra and hematosalpinx, and a fistulous tract extending from the obstructed horn to the left perianal skin. The fistula was presumed to be an acquired complication of prior undocumented pelvic surgery. Surgical excision of the obstructed horn and fistulous tract was recommended; however, the patient declined treatment and was subsequently lost to follow-up. This case highlights a rare and diagnostically challenging variant of OHVIRA syndrome complicated by a perianal fistula, likely acquired postoperatively. It underscores the importance of considering Müllerian anomalies in adolescent females with renal agenesis and pelvic pain, especially when imaging is inconclusive. Repeat imaging timed with menses and multidisciplinary input are essential for accurate diagnosis and management.