Background: Imperforate hymen is the commonest congenital anomaly that causes closure of the vagina. Ideally, diagnosis should be made early during fetal and neonatal examinations to prevent symptomatic presentations of its complications at puberty. Case report: We report a case of a 15-year-old girl who presented with delayed menarche, eight-month history of cyclic abdominal pain, and a three-week history of lower abdominal swelling. A doctor prescribed anthelmintic and analgesic drugs to her a month ago before she was verbally referred to ESUT Teaching Hospital, Enugu. The development of her secondary sexual characteristics was normal for her age. A 20 cm-sized suprapubic mass, and a bulging pinkishimperforate hymen were found on examination. Her transabdominal ultrasound revealed massive hematometra and hematocolpos. She had virginity-preserving hymenotomy and evacuation of about 1000 mls of accumulated coffee-colored menstrual blood. Conclusion: Clinicians should have high index of suspicion of imperforate hymen when assessing cases of delayed menarche with cyclic lower abdominal pain to prevent the consequences of its delayed treatment like massive hematometra and hematocolpos.
