Etiology of azoospermia in 100 consecutive nonvasectomized men.

History was taken systematically for 100 azoospermic, nonvasectomized men referred consecutively to a Danish fertility clinic. The men were examined by ultrasound, and their blood samples were analyzed for karyotype, Y microdeletions, and cystic fibrosis transmembrane conductance regulator gene mutations. In 29% of patients, the condition could be explained by genetic abnormalities; in 22%, by diseases or external influence; and in 27%, by former cryptorchidism. The azoospermic condition remained unexplained in only 22%.