Cryptorchidism

Cryptorchidism is the absence of one or both testes from the scrotum, with the missing testes in the inguinal canal. It is the most common birth defect of the male genitalia. The undescended testis will have impaired spermatogenesis (since spermatozoa develop best at temperatures less than 37° Celsius) but normal testosterone levels if unilateral (Leydig cells are unaffected by temperature). There is an increased risk of developing hypospadias of the penis or a seminoma of the affected testicle. Prematurity is associated with an increased risk of developing the condition. Serum inhibin B levels are decreased, while FSH and LH levels are increased. Testosterone is decreased in bilateral cryptorchidism, but normal in the unilateral variant.