Normal position of the testes at term birth is on the bottom of the scrotum. In 29% of newborn boys, the testes have failed to descend normally (cryptorchidism), and at the age of three months, 13% of all boys remain cryptorchid. Thereafter spontaneous descent occurs rarely, whereas testicular ascent starts to appear and acquired cryptorchidism becomes a problem almost as often as congenital disorder. Cryptorchidism is associated with an increased risk of testicular cancer and subfertility. Germ cell loss in a cryptorchid testis appears already during the second year, and therefore early orchidopexy is generally recommended for treatment. Early operation (before 1 year) has been reported to improve testicular growth as compared with later operation (at 3 years). Hormonal treatment with either human chorionic gonadotropin (hCG) or gonadotropin releasing hormone agonist is still used in some countries, although the efficacy is rather poor (approximately 20%) and some short-term and long-term potential side effects have been reported after hCG (interstitial bleeding, inflammation, increased apoptosis, reduced adult testicular size). The benefit is the avoidance of surgery. In most cases the reason for cryptorchidism remains elusive, although several rare genetic mutations disturbing hormonal regulation of testicular descent are known. Normal function of hypothalamo-pituitary-testicular axis is necessary, and disorders of synthesis/action of androgens and/or insulin-like peptide 3 can cause cryptorchidism. Environmental endocrine disrupters affecting these systems are suspected to be involved in etiology. Links to impaired semen quality, increased risk of testicular cancer and hypospadias suggest that cryptorchidism can be a part of testicular dysgenesis syndrome (TDS) where fetal maldevelopment of the testis can result in one or several signs depending on the timing and nature of the disrupting agent/event.
Declaration of interest: The author declares that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This work was supported, however funding details are unavailable.