Congenital adrenal hyperplasia: preliminary observations of the urethra in 9 cases

Congenital adrenal hyperplasia is the most common cause of androgen mediated virilization of the genitourinary tract in females. In our study relative lengths of the internal genital duct structure were compared with the degree of virilization of the external genitalia.

The records of 9 consecutive female patients with a median age of 2.6 years with congenital adrenal hyperplasia were studied. There were 4 normal females with a median age of 7.4 months who had a voiding cystourethrogram for urinary tract infection used as controls. The patients with congenital adrenal hyperplasia were stratified into groups as having mild, moderate or severe virilization based on preoperative photographs of external genitalia. By lateral voiding cystourethrograms the length of the proximal urethra, vagina and urogenital sinus was measured and standardized against the femoral metaphysis. The relative length of these internal genital structures was compared to the degree of virilization of the external genitalia.

There were 4 cases classified as normal, and 2 mildly, 4 moderately and 3 severely virilized. The urogenital sinus appeared to lengthen, with increasing virilization of the external genitalia. There was no trend for the proximal urethra to shorten with increasing virilization. The vagina also seemed to shorten with increasing virilization.

Our results suggest that the vagina enters the urogenital sinus at a fixed distance from the bladder neck. With increasing virilization, the majority of urethral lengthening occurs primarily distal to the vaginal opening, that is urogenital sinus lengthening.