Prenatal Ultrasonographic Diagnosis of Hydrometrocolpos

Prenatal diagnosis of an imperforate hymen remains a clinical challenge. We present a case of a 28-year-old female who was sent to our hospital for an anomaly scan at 32 weeks of gestation. The lower abdomen of the fetus showed a cystic mass, which was funnelling towards the vulva and measured approximately 5.8 × 3.9 cm. The mass showed low level internal echoes and was initially diagnosed as a distended urinary bladder with fluid debris level. The patient was made to wait for 30 to 45 minutes for emptying of the urinary bladder. After 45 minutes, the patient was rescanned and this time another cystic mass appeared adjacent to the existing mass, which was actually the filling of the urinary bladder. Since the sex of the fetus was female and the mass was separate from the urinary bladder funneling towards the vulva, we diagnosed it as a case of hydrometrocolpos.