Cryptorchidism: isolated and associated with other genitourinary defects.

Cryptorchidism is the most common disorder of sexual differentiation in male children, with an incidence of 3.4 per cent in the term newborn, decreasing to 0.8 per cent at 1 year of age. The mechanisms of normal testicular descent are multifactorial and include an intact hypothalamic-pituitary-testicular axis, as well as a normal gubernaculum and epididymis. In boys with cryptorchidism, the testes demonstrate degenerative changes histologically as early as 1 to 2 years of age. Both testes may be affected, even with a unilateral undescended testis. The most important long-term complications of cryptorchidism include infertility and testicular cancer. The risk of malignancy is approximately 40 times higher in male subjects with cryptorchidism than in normal men, and is highest in male subjects who have had an intra-abdominal testis and in certain intersex conditions. Orchiopexy does not appear to lessen this risk. Hormonal therapy with HCG or LH-RH has remained unproven in clinical trials in the United States; therefore, orchiopexy remains standard treatment. HCG is recommended if the clinician suspects that a testis is retractile, however. Orchiopexy should be performed between 12 and 18 months of age to prevent the degenerative changes that are demonstrable by 2 years.