Undescended testicles: an epidemiological review

In a retrospective study the records of 447 boys (median age 5 y, age range 2 wk to 12 y) undergoing orchidopexy in a university hospital paediatric s urgical department over a 2-y period were analysed for epidemiological fact ors related to disturbed testicular descent by comparison with the notes of an equal number of otherwise healthy male trauma patients matched for age. There were higher rates of peripartal asphyxia and intrauterine growth ret ardation (reflected by lower birthweights in combination with equal gestati onal age distribution), more complicated deliveries, an increased incidence of congenital malformations and more frequent occurrence of a number of ch ronic diseases in the families of affected boys. First- and second-born boy s were over-represented in the study group. A cyclical pattern for the mont h of birth is suggested by the data, but this did not reach statistical sig nificance. Neither was any statistical difference found for premature deliv ery, the incidence of extra-uterine fertilization, hormonal treatment of th e mother while pregnant, twin pregnancies, threatened or imminent abortions or parental age. The literature dealing with this topic was reviewed. Disc repancies between different studies can be explained, at least in part, by considering different forms of undescended testicles as different nosologic al entities that should be assessed separately in forthcoming research.