The phrase “a boy’s balls to drop” describes testicular descent, a necessary biological process during male fetal development. The two testes, which produce sperm and male hormones, migrate from their initial location inside the body to their final position in the scrotum. This journey must be completed for the male reproductive system to function correctly later in life. Understanding this process, its timing, and potential issues is important.
The Developmental Journey
The testes initially form high in the abdomen near the kidneys during the first few months of gestation. This migration to the scrotum is guided by the gubernaculum, a fibrous cord-like structure that shortens and helps pull the testis downward.
The descent occurs in two main phases: the transabdominal phase, which moves the testes to the entrance of the groin, and the inguinoscrotal phase, which involves passing them through the inguinal canal and into the scrotal sac. This intricate movement is regulated by hormones, including Insulin-like 3 (INSL3) and testosterone. The physical reason for this relocation is to ensure the testes reside outside the main body cavity.
The internal body temperature is too high for the healthy production of sperm, a process known as spermatogenesis. The scrotum acts as an external thermoregulator, maintaining a temperature that is a few degrees cooler than the core body temperature. This cooler environment is a biological necessity for future reproductive capacity, making successful descent a requirement for fertility.
Standard Timing and Variations
The majority of testicular descent happens during the last trimester of pregnancy, typically between the 25th and 35th weeks of gestation. Approximately 97% of full-term male infants will have both testes fully descended and palpable in the scrotum at birth. Descent is less common in premature infants because they miss the final weeks of this developmental stage.
For the small percentage of full-term newborns whose testes have not yet descended, they often complete their journey on their own shortly after birth. This spontaneous descent usually occurs within the first three to six months of life. If a testicle is felt in the groin area but can be easily guided down into the scrotum, it may be a “retractile testis.” This common variation is caused by an overactive muscle reflex that pulls the testicle up, but it does not require surgical intervention.
Understanding Undescended Testes
When one or both testes fail to reach the scrotum by six months of age, the condition is formally diagnosed as Cryptorchidism, or an undescended testicle. This is the most common male genital abnormality found at birth, affecting about 1% to 3% of full-term boys. Undescended testes may be located anywhere along the normal path of descent, such as in the inguinal canal, or in rare cases, still within the abdominal cavity.
Leaving the testes in an undescended position past infancy exposes them to the higher core body temperature, which can damage the cells responsible for future sperm production. This exposure significantly increases the risk of infertility or subfertility in adulthood, especially when both testes are affected. Even a single undescended testicle can increase the risk of infertility by 10% to 30%.
Cryptorchidism is one of the strongest known risk factors for developing testicular cancer later in life. The cancer risk is estimated to be five to ten times higher for men who had an undescended testicle compared to the general male population. Undescended testes are also more prone to testicular torsion, a painful medical emergency where the organ twists on its blood supply, which can lead to the loss of the testicle.
Addressing Undescended Testes
If a testicle has not descended on its own by six months of age, treatment is recommended because spontaneous descent is highly unlikely after this point. The goal of intervention is to move the testicle to the cooler environment of the scrotum before cell damage or other complications occur. Delaying treatment beyond one to two years can negatively impact the testicle’s ability to develop and function normally.
The primary treatment for a truly undescended testicle is a surgical procedure called Orchiopexy. This operation is generally performed between six and eighteen months of age. The surgeon makes a small incision, usually in the groin, to locate the testicle, free it from surrounding tissues, and then secure it within a small pouch created inside the scrotum.
Early Orchiopexy can significantly reduce the potential for fertility issues later on, although it may not completely eliminate the increased lifetime risk of testicular cancer. The procedure also moves the testicle into a position where it can be easily monitored through self-examination as the child grows into adolescence. Regular follow-up appointments with a pediatrician or urologist are necessary after the surgery to ensure the testicle remains in the correct position and to monitor its health.