Vasa aplasia and cystic fibrosis.

Bilateral vasa aplasia is considered an invariable finding in cystic fibrosis, but such patients are rarely seen in male infertility clinics. The improved survival beyond 20 years of age is likely to change this. In a clinical study of a group of male cystics the vasa were absent in 8 of 11 boys and epididymal abnormalities were palpable in the majority. The main cause of infertility appears to be mechanical obstruction. Whether the absence is due to a primary failure of mesonephric duct development or secondary to luminal obstruction and subsequent atrophy is not known.