Pain after vasectomy

We studied the influence of the timing of injection of bupivacaine into the vas deferens on the intensity and duration of scrotal pain following vasectomy. Forty-two patients undergoing vasectomy under general anaesthesia were randomly allocated to have the operation performed on either the left or the right side first. On the first side to be operated upon, 5 ml bupivacaine 0.5% was infiltrated along the line of the scrotal incision. The vas deferens was identified and 1 ml bupivacaine 0.5% was injected into its lumen, with 0.5 ml directed proximally and 0.5 ml directed distally. After completion of the procedure on that side, the operation continued on the other side. On this occasion, the same dose of bupivacaine was injected into the vas deferens after division and ligation, and subcutaneously along the scrotal incision after skin closure. Median [interquartile range] visual analogue pain scores on the first side to be operated upon were significantly lower than on the second side on day 1 (7 [1.5-19] vs. 11 [2.5-47]) (p < 0.01) and day 7 (0 [0-8.5] vs. 0 [0-18.8]) (p < 0.05) postoperatively. The median [interquartile range] duration of postoperative discomfort was less on the first side operated upon than on the second (3 [1-7] vs. 6 [2-7]) (p < 0.01). Although statistically significant differences occurred between the treatment groups, the actual differences were small and may not be clinically significant.