Undescended testis (cryptorchidism) is a condition in which the testicle is not located in the scrotum and cannot be properly felt. Instead of descending along its normal pathway, the testis may remain in the inguinal region, abdomen, or another abnormal location (ectopic testis). Treatment is recommended between 6 and 12 months of age to prevent potential complications. In some cases, the testis may be absent or severely underdeveloped, and even when present, it is often smaller than a normally descended testis.
During fetal development, the testes form in the abdominal cavity and descend into the scrotum before birth. When this process is disrupted, the testis fails to reach the scrotum, resulting in cryptorchidism. Although the exact cause is not fully understood, several factors have been proposed. These include dysfunction of the structures that guide testicular descent, lower-than-normal intra-abdominal pressure, congenital abnormalities of the testis, or hormonal influences affecting the descent process.
There are two main reasons why treatment of undescended testis is essential.
First, it reduces the risk of infertility. The testes need to be located in the scrotum, where the temperature is approximately 1–2°C lower than core body temperature, to support normal sperm production. When the testis remains outside the scrotum, exposure to higher temperatures can impair spermatogenesis. In fact, degeneration of the testis can begin as early as one year of age. By age four, the testis may become firm, and by around six years of age, it may progressively shrink. Semen analysis in patients with cryptorchidism shows abnormalities in approximately 50% of unilateral cases and up to 75% of bilateral cases.
Second, early treatment helps reduce the risk of testicular cancer. Patients with undescended testis have been reported to have a fivefold higher risk of developing testicular cancer compared to the general population. Additionally, about 10% of all testicular cancer cases occur in individuals with a history of cryptorchidism. While surgical correction does not completely eliminate this risk, it allows for easier examination and earlier detection. When the testis is positioned in the scrotum, abnormalities can be identified more readily, improving the chances of early diagnosis and treatment.
Diagnosis is typically made through physical examination and ultrasound imaging. The child may be positioned with legs flexed or in a frog-leg position to facilitate palpation. If the testis cannot be felt, ultrasound is used to locate it within the inguinal canal or abdominal cavity. Only about 30–40% of undescended testes are palpable, making imaging essential in many cases. Accurate localization is important because the surgical approach depends on the position of the testis.
As noted earlier, treatment is necessary to prevent infertility and reduce cancer risk. Early intervention is strongly recommended, ideally between 6 and 12 months of age. While spontaneous descent may occur before 6 months, the likelihood decreases significantly afterward. Therefore, treatment should generally be completed by 18 months of age at the latest.
The primary treatment is orchiopexy, a surgical procedure that creates a space in the scrotum and secures the testis in its proper position. This procedure is widely performed due to its high success rate and relatively low risk. In cases where the spermatic vessels are too short to allow immediate descent, a staged surgical approach may be used. If the testis is severely underdeveloped or nonviable, testicular autotransplantation or removal may be considered. Hormonal therapy has also been used in some cases to stimulate testicular descent, although its effectiveness is variable.
Through systematic diagnosis and treatment, patients with undescended testis can achieve favorable outcomes. If any abnormalities are suspected in a child, prompt evaluation by a specialist is important. Early diagnosis and timely treatment play a crucial role in ensuring healthy growth and long-term well-being.