<Tr> <Th> MeSH </Th> <Td> D003456 </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> Cryptorchidism is the absence of one or both testes from the scrotum . The word is from the Greek κρυπτός, kryptos, meaning hidden ὄρχις, orchis, meaning testicle . It is the most common birth defect of the male genital . About 3% of full - term and 30% of premature infant boys are born with at least one undescended testis . However, about 80% of cryptorchid testes descend by the first year of life (the majority within three months), making the true incidence of cryptorchidism around 1% overall . Cryptorchidism may develop after infancy, sometimes as late as young adulthood, but that is exceptional . </P> <P> Cryptorchidism is distinct from monorchism, the condition of having only one testicle . Though the condition may occur on one or both sides, it more commonly affects the right testis . </P>

Failure of the testes to descend into the scrotum at birth