Etiology and incidence

What are the risk factors?

Caregivers should be asked for both maternal and paternal risk factors, including hormonal exposure, tobacco smoking, and genetic or hormonal disorders. The risk of cryptorchidism increases 3.5 times when a sibling is affected, and 2.3 times when a father is affected.

Undescended testes are also found in some clinical syndromes (Klinefelter's syndrome), hormonal disorders (pituitary insufficiency, testosterone production, 5-alpha-reductase deficiency, androgen receptor insensitivity), and abdominal wall developmental defects (prune-belly syndrome, gastroschisis, omphalocele).


Incidence varies and depends on gestational age, affecting approximately 3% of full-term and 30 % of preterm neonates. Despite spontaneous descent within the first months of life, nearly 1.0% of all full-term male infants still have undescended testes at 1 year of age.

An undescended testis rarely descends after the age of 6 months. Most of the cases are unilateral (85%) and less often bilateral (15%).





6 months


12 months


Cryptorchidism | 1. basics of cryptorchidism
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