Cryptorchidism: a prospective study of 7500 consecutive male births, 1984-8. John Radcliffe Hospital Cryptorchidism Study Group.

A total of 7441 boys were examined for cryptorchidism at birth and, if present, again at 3 months of age. After excluding boys with severe congenital malformations noted at birth, the cryptorchidism rates at 3 months in babies weighing less than 2000 g, 2000-2499 g, and greater than or equal to 2500 g were 7.7%, 2.5%, and 1.41% respectively. The overall rate was 1.55%. The cryptorchidism rate at birth had increased by 35.1% and at 3 months by 92.7%, over Scorer's rates in the 1950s. Part of these increases may be attributable to differences in neonatal mortality, but the increases in babies weighing 2500 g or more of 50.2% at birth and 77.4% at 3 months are unlikely to be overestimates. At birth 1.92% of boys had bilateral cryptorchidism and 3.0% unilateral cryptorchidism. Boys with cryptorchidism at 3 months were more likely to have hypospadias, a small scrotum, and poor scrotal rugation compared with boys having normally descended testes at birth. Factors predicting descent by 3 months in babies cryptorchid at birth are birth weight, laterality and scrotal size, babies with low birth weight, bilateral cryptorchidism, and normal scrotal size being more likely to have normally descended testes by 3 months. Descent by 3 months was more likely the lower the testis along the normal pathway of descent. The orchidopexy rate at an average age of 3 years was 1.24%. This is substantially lower than in other series and lower than our estimated rate of 2.9% using Hospital In-Patient Enquiry data for England and Wales.