Undescended testicle: An update on fertility in cryptorchid men.

Cryptorchidism or undescended testis is one of the most common anomalies encountered in paediatric urology and is estimated to affect 1 to 4 per cent of full term and upto 30 per cent of preterm male neonates. The associated problems of sub-fertility or infertility and malignant transformation have been recognized for long. Fertility is impaired after both unilateral and bilateral cryptorchidism. The reported paternity rates in adults are about two-third for unilateral undescended testis and less than one-third for bilateral disease. Over the last five decades, the concepts related to cryptorchidism have changed dramatically as knowledge about its effects has accrued from research conducted worldwide. The recommended age of orchidopexy has fallen progressively from adolescence to less than one year. The realization that the infantile testes are not in a state of 'suspended animation' and the recognition of the defect in the androgen dependent transformation of gonocytes into adult dark spermatogonia in cryptorchidism have been recognized as the primary cause of sub-fertility in these patients. This has paved the way for hormone therapy in an attempt to simulate the 'post-natal gonadotropin surge' or 'mini-puberty'. This review summarizes the current knowledge about the various factors affecting the fertility status in cryptorchidism with a particular focus on the derangements in the development and maturation of the germ cells and the role of surgery, hormone therapy and antioxidants in reversing these changes.