Cryptorchidism, as the name implies, is a hidden testicle. Another name: incomplete testicular descent is better understood as the testicle is not in its normal position (i.e. scrotum) and is a common urological condition in young boys. The incidence of cryptorchidism ranges from 3.4% to 5.8% among full-term newborns. As children grow older, some of them continue to descend into the scrotum, and the prevalence is around 0.8% by 6 months of age, but there is still a 10% prevalence among premature babies. There are many high-risk factors, such as high maternal age, maternal obesity, prematurity, low birth weight, and even high consumption of cola drinks during pregnancy. The clinical manifestation is that the testicles cannot be felt in one or both scrotums. Of course, is it true that every child who cannot feel the testicles in the scrotum has cryptorchidism? The answer is no. There are some diseases, including congenital testicular atrophy or testicular agenesis, testicular ectopic or transverse ectopic testicles, which also prevent the testicles from being palpated in the scrotum, but of course, these diseases are still within the scope of cryptorchidism. Sometimes the testicle is difficult to be touched by parents due to contraction of the levator muscle to the root of the scrotum or inguinal area, and clinically diagnosed testicular retraction or sliding testicle generally falls under this condition. The harmful effects of cryptorchidism include the abnormal position of the testicles which affects the development of the testicles. Generally speaking, the position of the scrotum is slightly lower than the body temperature, which is also the temperature needed by the testicles, and if the testicles are in the groin or abdominal cavity for a long time, the higher temperature is not suitable for the development of the testicles and affects the development of sperm. Cryptorchidism is mostly combined with hiatal hernia (hidden or with clinical symptoms), which may be accompanied by testicular or intestinal necrosis due to hiatal hernia entrapment. Occasionally, testicular torsion occurs in cryptorchidism. In addition, one side of the scrotum is empty, leading to psychological stress for the child and parents, which may lead to psychological disorders in the long run. The treatment of cryptorchidism currently includes hormone treatment and surgery. There are hormones such as chorionic gonadotropin (HCG), GnRH or LHRH (LH-releasing hormone), but only HCG is available in China. Many parents are hesitant to apply hormone therapy, worrying about the side effects of hormones. I personally believe that hormone (HCG) is still available, and its side effects are mainly from the side effects of increased testosterone after the application of HCG, including scrotal coloration, scrotal penis enlargement, testicular enlargement, and penile erection, which usually subside or mostly subside after stopping the medication. As for the issue of hormone efficacy, many parents are concerned about whether they should not have surgery after using hormones. In the literature, especially the early literature, hormone has a high cure rate, but it seems that according to my observation, including peer-to-peer communication, only a very few patients are cured by hormone treatment to achieve a satisfactory testicular position, and the majority of patients still need surgery at the same time. Surgery for cryptorchidism is already a very mature surgery, and in China, it is generally performed around the age of 1 to 2 years old, and I tend to prefer surgery around the age of 1. Most patients can still lower their testicles into the scrotum through surgery; of course, for a few patients with high testicular position, especially in the abdominal cavity, some of them still have high testicular position after surgery. The rate of testicular atrophy after surgery is still relatively low when the surgery is mastered skillfully. Traditional open surgery is still the preferred surgical approach for many surgeons. Laparoscopic surgery is very advantageous for exploring the non-palpable testis. Laparoscopic surgery is gradually being partially carried out for cryptorchidism where the testicles can be felt. It is still advantageous for suitable patients to choose laparoscopic surgery, especially for the aesthetic appearance of the postoperative wound. After cryptorchidism surgery, even if the surgery is very successful, the testicle on the affected side still has abnormal development after the surgery, and it is common that the testicle on the affected side is generally smaller than the normal testicle. Dr. Lee’s research suggests that bilateral cryptorchidism has a 38% infertility rate compared to 6% for normal controls, which means a 6 times higher risk of infertility than normal. Unilateral cryptorchidism has a 10.5% infertility rate. Of course, parents do not need to worry too much. With the development of medical science and assisted reproduction, the infertility situation will be gradually improved by medical technology. If the parents touch the scrotum of the affected child and suspect that the testicles are not touched, they should seek the help of a pediatric urologist in time, and a careful physical examination and ultrasound examination can usually make a clear diagnosis. Once cryptorchidism is diagnosed, all treatment should be completed before 2 years of age. Performing cryptorchidism surgery at an older age (older than 2 years) will make the surgery more difficult and reduce the success rate.