Basic knowledge about cryptorchidism: Cryptorchidism is defined as the failure of the testicles to descend from the lumbar retroperitoneum to the scrotum according to the normal developmental process. Cryptorchidism is an important cause of male infertility or the development of testicular cancer. The incidence of cryptorchidism still has the chance to continue to decline after birth, but after 1 year of age, the chance of decline decreases significantly. The etiology of cryptorchidism is unknown. It is currently believed that the etiology of cryptorchidism is related to multiple factors such as endocrine, genetic and physical-mechanical. The testes of cryptorchidism often have different degrees of dysplasia, and are significantly smaller in size than the healthy side with a flabby texture. The pathological changes of cryptorchidism become more obvious with increasing age. The higher the location, the more serious the pathological damage is, while the closer to the scrotum, the less severe the pathological damage is. Even in bilateral cryptorchidism, there is a certain amount of androgen production, which can maintain the development of male secondary sexual characteristics and rarely affects the sexual behavior in adulthood. The diagnosis of cryptorchidism can be confirmed by clinical manifestations and physical examination. In bilateral cases, the development of scrotum is even worse, and there is even no obvious scrotum. On palpation, the scrotum on the affected side is empty and there is no testicle. However, it should be noted that the absence of testicles in the scrotum is not always cryptorchidism. It should be distinguished from retractile testis and sliding testis. Retractile testis: The testis can be pushed into the scrotum and can stay in the scrotum for a period of time after releasing the hand. Sliding testicle: If the testicle is pushed into the scrotum and immediately returns to the original position after releasing the hand, it is a sliding testicle and belongs to cryptorchidism. Treatment of cryptorchidism: After the diagnosis of cryptorchidism is clear, treatment should be given as soon as possible so that the testicles in abnormal position can be lowered to the normal scrotal position. If the testicle does not descend after 6 months of life, there is little chance that it will descend on its own.