Apparent doubling of frequency of undescended testis in England and Wales in 1962-81.

Examination of Hospital Inpatient Enquiry data for England and Wales for the years 1962-81 shows that the annual number of discharges with a diagnosis of undescended testicle has risen by a factor of 2.3. Cohort analysis suggests that the cumulative rate to age 15 of discharge for undescended testis has risen from 1.4% for the 1952 birth-cohort to 2.9% for the 1977 birth-cohort. Whether this is a reflection of an increase in true cryptorchidism is not known. Changes in known risk factors for cryptorchidism--exogenous oestrogen exposure, being first-born, and low birth-weight--cannot fully account for the apparent increase. With the tendency to carry out orchidopexies on apparently undescended testes at younger ages in order to preserve fertility, it is possible that a considerable number of boys with retractile testes that would have descended naturally at puberty are now being operated upon.