In embryonic life, the testicles are initially “lodged” in the abdominal cavity, and then gradually descend as the fetus develops. At 5 months of age, both testes descend to the inguinal ring, and at 9 months, they descend into the scrotum. Therefore, two testicles can be touched in the scrotum of a normally developing baby boy at birth. If, for some reason, the testicles stay in the middle of the descent process and cannot enter the scrotum, cryptorchidism is formed. If only one testicle can be felt in the scrotum, it is called unilateral cryptorchidism; if neither testicle can be felt, it is called bilateral cryptorchidism. There are also a few male babies whose testicles descend into the scrotum only a few months to a year after birth. What is the harm of cryptorchidism: Cryptorchidism is a manifestation of abnormal development of male infants, and its consequences are very serious. (1) It affects fertility. Some data show that 30% to 60% of patients with unilateral cryptorchidism are infertile. In bilateral cryptorchidism, 50% to 100% of patients are sterile. (2) Malignant tumor is easy to occur because the testicles are in the abdominal cavity with high temperature. (3) The testes are in the superficial position of the groin or abdominal cavity and are relatively fixed, so they are easily squeezed and lead to testicular tissue damage. Therefore, male babies must pay attention to the examination of testicles after birth, and if cryptorchidism is found, it should be treated early under the guidance of doctors.