Acute urinary retention in two adolescent girls with imperforate hymen.

Acute urinary retention is rare symptom in young adolescent girls. Imperforate hymen can be a cause of acute urinary retention possibly due to the pressure effect of the distended vagina (hematocolpos) on the lower urinary tract. However, the mechanism of progression to urinary retention is unknown. We report on two cases of adolescent girls with imperforate hymen who presented with acute urinary retention. A series of volume tolerance tests of the urinary bladder and urodynamic studies before operation revealed highly elevated urethral resistance, which was induced by interaction of large amount of urinary volume in the bladder and the large size of hematocolpos. After operation, urinary retention could not be observed and the urethral pressure returned to normal.