(You may wish to read the FAQ, 'What is the likelihood of a Vasectomy Reversal being successful and what are the factors involved?')

Some of the best success rates reported in the literature for vasovasotomy are a patency rate of 99% with a pregnancy rate of 64%, not including couples where the woman was infertile. This means that in the hands of the surgeon who quoted these rates, he was able to restore sperm flow in the vas tube 99% of the time, and this allowed a pregnancy rate of 64%.

Not every time that sperm flow returns to the vas is pregnancy guaranteed. The expected results for vasoepididymostomy in the hands of the same surgeon are lower, reportedly at 65% patency rate and a 41% pregnancy rate.

Factors influencing the success rate of reversal surgery include the following:

• Time interval since vasectomy
  The length of time passed since the vasectomy greatly impacts success, as seen on this chart:

As previously noted, with longer intervals between vasectomy and reversal, there is an increased rate of epididymal blockage as well as rupture and obstruction of the epididymal tubules.

• Sperm granuloma
  Sperm granulomas at the vasectomy site are a favourable prognostic sign and increase the likelihood of success.
  
• Anti-sperm antibodies
  Post-operative, sperm-bound antibodies result in a lower pregnancy rate.
  
• Quality of vasal fluid
  Vasoepididymostomy is required when sperm are absent in the vasal fluid. As noted previously, the vasal fluid is checked before decision is made whether to proceed with a vasovasotomy versus vasoepididymostomy to reverse the vasectomy.
  
• Microsurgical technique
  Technique, judgment and experience are important factors for success.
  
• Associated conditions
  Any condition that impairs sperm production for example a varicocele may lower postoperative pregnancy rates.
  

If a man has had a failed vasectomy reversal, it is reasonable to have a repeat reversal surgery. These can often be successful.

• In one study that looked at the patency and pregnancy rates of a repeat attempt at vasectomy reversal, success rates only dropped slightly: the second reversal surgeries yielded a 75% patency rate versus a 86% patency rate for vasectomy reversals that were successful in the first attempt.
  
• In another study group where success was obtained on the first attempt reversal surgery, second attempt reversal surgery yielded a 43% pregnancy rate compared to a 52% pregnancy rate on the first attempt.
  

Therefore it is not necessary to give up after one failed reversal attempt. However, one may want to look carefully at making sure the second attempt maximizes all the factors responsible for successful surgery in the favour of the patient.

When a vasectomy reversal surgery is successful with a vasovasotomy, it can often take three months or more for the semen analysis to reveal a good sperm count. Sperm count usually will be better quality after six months.

After a vasoepididymostomy, sperm usually takes longer to appear in the ejaculate and in most cases can take four to six months. In general, the first semen analysis after a vasectomy reversal is often obtained within one or two months, and then every two to three month after until sperm counts and sperm movement are normal, or until pregnancy occurs.

Even if a couple does not plan to conceive right away, it is best not to delay having a vasectomy reversal. The average time interval from vasectomy reversal until pregnancy is twelve months, and it can often take two years or longer for the highest percentage of pregnancies to be achieved. Couples must also consider that after an initially successful vasectomy reversal, i.e., when patency is achieved, a late obstruction will occur in up to 12% of men by fourteen months after the operation. This means that if sperm flow is demonstrated after vasectomy reversals couples should not wait to attempt achieving a pregnancy. At a minimum, semen should be stored for future use should pregnancy fail to occur with regular intercourse.