Microperforate hymen in a primigravida in active labor: a case report.

BACKGROUND

A microperforate hymen is a rare congenital hymenal anomaly frequently mistaken for an imperforate hymen. While an imperforate hymen is suggested when hematocolpos is present and the hymen bulges and is discolored by retained menstrual blood, a microperforate hymen is an incomplete obstructive anomaly usually permitting normal menstrual flow. The microperforation is quite difficult to visualize.

CASE

A 21-year-old primigravida at 38 weeks' gestation in active labor was referred to a university hospital because of absence of a vaginal opening. Inspection revealed normal external genitalia with an obstructing membrane at the level of the introitus. Because of arrest of labor coupled with lack of a definitive diagnosis, a cesarean section was performed. Subsequent digital exploration confirmed the diagnosis of microperforate hymen.

CONCLUSION

A pinhead-sized opening of the hymen can permit spontaneous pregnancy. Lack of awareness of this unusual entity can cause diagnostic difficulty.