Vaginal agenesis occurs in one in 4,000 to one in 5,000 women.'-3 The apparent absence of the vagina may be caused by imperforate hymen, vaginal agenesis, testicular feminization, or fused labioscrotal folds secondary to congenital adrenal hyperplasia, true hermaphroditism, or exposure to exogenous androgens. When a patient presents with primary amenorrhea and the pelvic examination shows the apparent absence of the vagina, the principal diagnoses to consider are imperforate hymen and vaginal agenesis. Imperforate hymen is usually clinically obvious because of a bulging hymen with blood behind it. If there is no bulging obstruction, vaginal agenesis is the major consideration. However, the extent of the vaginal agenesis often cannot be determined on physical examination, and sonographic examination is recommended to delineate more completely the level and extent of the lesion. Two cases are presented in which combined abdominal-perineal scanning allowed a more precise delineation of the extent of vaginal agenesis than could be obtained by abdominal scanning alone.
CASE 1A 16-year-old female presented with primary amenorrhea. There were no complaints of recurrent abdominal pain or any urinary tract complaints. Physical examination showed normal external female sex characteristics and a normal hymen, but complete vaginal atresia just above the hymen was found. Bimanual examination showed a soft fluctuant mass extending from the level of the obstruction into the pelvis. Sonographic evaluation using an abdominal approach