Pregnancy rates are dependent on several factors. First, there is generally a decline in technical success rates—due to the increasing need to perform more complex and difficult epididymal repairs—as time from vasectomy increases.
More importantly, pregnancy rates also decline because sperm quality and fertility tend to deteriorate progressively with time after vasectomy, due to the effects of chronic obstruction on the duct system—especially on the epididymis. These changes often result in larger numbers of sperm which have poor motility and decreased ability to penetrate and fertilize the egg. Decreasing fertility with increasing patient age may also play a role.
Traditionally, the pregnancy rates (i.e., the percentage of couples able to achieve pregnancy) for reversal surgery in most studies has been approximately the following:
These historical pregnancy rates may no longer be accurate, however. In his over 25 years experience with reversal surgery, including numerous epididymal repairs, Dr. Finnerty began to notice several interesting facts. First, in patients undergoing successful epididymal repairs, pregnancy rates were surprisingly good - even when patients were many years out from vasectomy. Secondly, when the epididymis was explored in men in whom epididymal obstruction was present, sperm quality in the proximal epididymis (closest to the testes) was excellent, with a high precentage of active sperm, while sperm in the mid- and distal epididymis (farther from the testes) was often inactive and of poor quality. Thirdly, when men without epididymal obstruction had poor-quality sperm at the vasectomy site, their surgery was usually technically successful (good sperm counts afterwards), but pregnancies were relatively rare and problems with sperm motility common.
These findings were also noted by Dr. Sherman Silber, one of the pioneers in microsurgical reversal surgery. They indicate that the epididymis develops abnormal function as a result of obstruction, and in many men, epididymal repair will improve pregnancy rates, even when epididymal obstruction is not present.
The main barrier to using these findings to achieve better pregnancy rates has been the ability to perform epididymal repair with high technical success rates. The extremely delicate nature of the epididymal tubule requires extensive surgical experience in order to achieve success. Using his many-year experience combined with new surgical techniques for epididymal repair, Dr. Finnerty has been seeing technical success rates up to 85-90% in surgeries performed over the last several years, and pregnancy rates - even in men who are many years out from vasectomy - look increasingly optimistic.