在卵子受精后12周至7个月间,睾丸由腹膜后腰部经腹股沟管下降至阴囊。在下降过程中睾丸停留在不应停留的位置,就形成睾丸下降异常,睾丸下降不全或睾丸未下降称之为隐睾。隐睾在未成熟儿中占9.2%～30%,在成熟儿中占3.4%～5.8%。引起睾丸下降不全或睾丸未下降的主要原因是:1)睾丸 Between 12 and 7 months after fertilization, the testes drop from the retroperitoneal to the scrotum through the inguinal canal. In the process of descending testicular rest should not stay in the position, the formation of abnormal testicular descent, testicular descent or testicular decline is not known as cryptorchidism. Cryptorchidism is 9.2% to 30% in immature children and 3.4% to 5.8% in mature children. Cause of testicular descent or testicular decline is not the main reason: 1) testicular