The case most likely to have a successful outcome is the man who has had a vasectomy done within the last 24 months and who has a partner with proven fertility, whilst the least successful is the older man with a vasectomy going back 15 or 20 years with a partner who has never had a child. I have operated on the whole spectrum of men and have had success at both ends so to speak, but overall I would expect there to be significant numbers of sperm in the ejaculate in about 85% of cases, and a successful pregnancy to ensue in about 50% of cases over the two year period following surgery. Whilst statistics are fine to predict how a whole group will respond to a treatment, they are of no use at all in predicting the individual