Apparent fertility of human spermatozoa from the caput epididymidis.

Fifty-one patients with obstructive azoospermia caused by blockage at the caput epididymidis have been followed for 4 years after undergoing "specific tubule" vasoepididymostomy, bypassing the corpus and cauda. The patency rate was 73%, and the pregnancy rate was 31%. There was no correlation between sperm count and pregnancy rate, but there was a strong correlation with sperm motility. With less than 20% motility, only 15% of the patients became pregnant, but with greater than 20% motility postoperatively, 58% became pregnant. If the wife was over 30 years old, only 21% got pregnant. If the wife was under 30, 67% got pregnant. "Redo" cases were just as likely to succeed as "first-time" attempts. In the "patent" cases, 43% of patients with spermatozoa that never reached or traversed the corpus or cauda epididymidis produced a pregnancy. Spermatozoa from the proximal caput produced a 33% pregnancy rate, whereas spermatozoa from the distal caput produced a 50% pregnancy rate. One-half of the pregnancies occurred more than 2 years postoperatively.