Cryptorchidism

Abstract

Testicular descent is controlled by the hypothalamic- pituitary-testicular axis and requires a complex series of anatomical changes, especially in the genitoinguinal ligament or gubernaculum. The latter structure undergoes an initial swelling reaction, and then profound remodeling to enable it to migrate to the scrotum along with the testis, which descends inside a special peritoneal diverticulum within the gubernaculum, the processus vaginalis. The first phase of descent is regulated by insulin-like hormone 3 (INSL3), which is the second inguinoscrotal phase controlled by androgens, which appear to act indirectly via the genitofemoral nerve. Cryptorchidism, or undescended testis (UDT), is probably caused by multiple different anomalies in the regulation of the two stages of descent, but the common causes remain unknown. Congenital UDT results from failure of gubernacular migration before birth, while acquired UDT developing in children is caused by failure of the spermatic cord to elongate in proportion to growth of the boy as a whole. UDT interferes with germ cell development in the testicular tubules shortly after birth, most likely secondary to the abnormally high ambient temperature of the testis in the groin rather than the specialized, low-temperature environment of the scrotum. Evidence is emerging that orchidopexy is likely to be optimal between 6 and 12 months of age to allow postnatal germ cell development to occur at the correct temperature, so that there are adequate numbers of spermatogenic stem cells after puberty and no abnormal primitive germ cells that might predispose to malignancy. Orchidopexy should be done by inguinal or scrotal route for palpable testes, but laparoscopy, first for diagnosis and then orchidopexy, is now the gold standard for impalpable UDT. Long-term follow-up is still required to confirm the current view that early surgery at 6 to 12 months should improve the prognosis for fertility and malignancy risk.