Cryptorchidism, the failure of one or both testes to descend into the scrotum, is one of the most common birth defects of the male genital tract. Risk factors include a positive family history, prematurity, trisomy 21, and Klinefelter syndrome.
- Etymology: “Crypt” and “orchid” come from Greek words for “hidden” and “testicle”, respectively.
Most testicles that are undescended at birth complete their descent within the first 4-6 months of life; spontaneous descent is unlikely to occur thereafter and generally requires surgical repair (aka orchiopexy).
In the presence of an undescended testicle, the physical exam is essential to determine the approximate location of the testicle as well as whether it is ectopic (deviates from the expected path) or retractile (can be brought down into the scrotum without tension but retracts back to a suprascrotal position after a variable period of time).
- One suggested approach to the exam is to place one hand near the anterior superior iliac spine (ASIS) and the other on the scrotum. The first hand’s finger tips are swept along the inguinal canal to gently express any testicular tissue into the scrotum. A true undescended inguinal testis may slide or “pop” under the examiner’s fingers during this maneuver. A retractile testis may be felt by the second hand as the testis is milked into the scrotum by the first hand.
- The cremaster muscle is thought to be hyperactive in the presence of a retractile testis. Thus, a retractile testis that is briefly held in the scrotum allows the cremaster muscle to fatigue and relax, allowing a retractile testis to remain in the scrotal position temporarily. Previously thought to be a normal variant, regular surveillance is advised in cases of retractile testes because of the risk of acquired or ascending cryptorchidism.
Interestingly, ultrasound has no role in the routine evaluation of cryptorchidism. A 2011 systematic review found that ultrasound had an estimated sensitivity and specificity of 45% and 78%, respectively, to accurately localize non-palpable testes. In contrast, diagnostic laparoscopy has nearly 100% sensitivity and specificity for localizing non-palpable testes and allows for concurrent surgical correction.
Two consequences of cryptorchidism are of concern: infertility and malignancy.
- Infertility: A population-based cohort study published in the Lancet showed that cryptorchidism was associated with a 2-times increase in use of assisted reproductive technologies. Furthermore, a smaller cohort study showed the paternity rate in men who had a prior unilateral or bilateral orchiopexy was 89.7% and 65.3%, respectively (versus 93.2% in control men).
- Malignancy: A review published in the Journal of Urology concluded that
- 1) the overall relative risk of cancer in patients with cryptorchidism is up 8 times that of controls;
- 2) surgical correction before age 10 to 12 years lowers the relative risk of developing malignancy to a relative risk less than 3;
- 3) there is no risk of the contralateral testis developing cancer. Furthermore, if a malignancy develops, the most likely type to occur in cryptorchid testicles is a seminoma.