There are at least four reasons that a vasectomy reversal can fail. One of the most common is when the two ends of the vas deferens pull apart, and this can take place if you put too much strain on your body during the 8 week surgical recovery period. Other potential failure causes include poor surgical technique, the wrong surgery being performed (i.e. vasovasostomy performed when an epididymovasostomy was required), or delayed stenosis (scarring).
