Results of microsurgical vasoepididymostomy: role of epididymis in sperm maturation.

One-hundred-and-ninety patients with obstructive azoospermia caused by bilateral epididymal blockage have been followed for greater than or equal to 4 years after undergoing 'specific tubule' vasoepididymostomy. When anastomosis was required in the corpus epididymidis, the 'patency' rate was 78% and the overall pregnancy rate was 56%. The pregnancy rate for 'patent' cases was 72%, indicating that a high fertility rate can be obtained with spermatozoa that have not passed through the full length of corpus epididymidis. By contrast, with vasoepididymostomy to the caput epididymidis there was a 73% 'patency' rate, but the overall pregnancy rate was only 31%. The pregnancy rate for 'patent' cases was 43%. Spermatozoa from the corpus epididymidis have a higher rate of fertility than spermatozoa from the caput epididymidis, but spermatozoa from proximal areas of the corpus have no less fertility than spermatozoa from the distal corpus epididymidis. The most remarkable observation is that in almost half the cases, spermatozoa which have never journeyed beyond the caput epididymidis seem to be capable of causing pregnancy.