A transverse septum can form during embryogenesis when the Müllerian ducts fuse improperly to the urogenital sinus. Its incidence is estimated at 1 in 30,000 to 1 in 80,000 women. A complete transverse septum will block menstrual flow and is a cause of primary amenorrhea. The accumulation of menstrual debris behind the septum is termed cryptomenorrhea. Some transverse septa are incomplete and may lead to dyspareunia or obstruction in labor. A surgical incision will relieve the situation.
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