One or both testes may be absent from the scrotum at birth in about 20% of premature or low-birth-weight male infants and in 3–6% of full-term infants. Cryptorchidism is found in 1–2% of males after 1 year of age but must be distinguished from retractile testes, which require no treatment. Infertility or subfertility occurs in up to 75% of men with bilateral cryptorchism and in 50% of men with unilateral cryptorchism. Some patients have underlying hypogonadism, including hypogonadotropic hypogonadism.
For a testis that is not palpable, it is important to locate the testis and bring it into the scrotum or prove its absence. About one-third of nonpalpable testes are located within the inguinal canal, one-third are intra-abdominal, and one-third are absent. Ultrasound can detect an inguinal testis. If ultrasound is negative, MRI is performed to locate the testis. Surgery for cryptorchid testes (orchiopexy) should be performed by age 12–24 months and is generally successful. Alternatively, hCG, 1500 units intramuscularly daily for 3 days, causes a significant rise in testosterone if the testes are present. Therapy with hCG results in a testicular descent rate of about 25%.
The lifetime risk of testicular neoplasia is 0.002% in healthy males. The risk of malignancy is higher for cryptorchid testes (0.06%) and for intra-abdominal testes (5%). Orchiopexy decreases the risk of neoplasia when performed before 10 years of age. For bilateral undescended testes, boys with early orchiopexy (before age 13 years) appear to have relatively normal fertility, whereas boys with delayed orchiopexy may have reduced fertility. With a unilateral undescended testis, about 50% descend spontaneously and early orchiopexy does not improve fertility, so orchiopexy is usually delayed until after puberty. For intra-abdominal testes, orchiectomy after puberty is usually the best option.
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