The aim of this randomized and double-blind study was to introduce and examine the clinical utility of an improved ultrasound-guided pudendal nerve block technique, and compare the effective of two different postoperative analgesia techniques, local infiltration analgesia and pudendal nerve block for PPH operation.

A total of 60 patients with mixed hemorrhoid were divided into ultrasound-guided pudendal nerve block group (Group PNB) and local infiltration analgesia group (Group LA) with 30 patients each. Group PNB received ultrasound-guided PNB after the surgery: 0.5% ropivacaine 10 mL each side and 0.5% ropivacaine 20 mL for Group LA. The postoperative analgesia effect measured by Median VAS pain scores. The Analgesia requirements, nausea and vomiting, spasm of anal sphincter during the first 48 postoperative hours and the satisfaction of the patients were also recorded. Ultrasound-guided assessment was confirmed by the anatomical structure and the local anesthetic expanding.

There was a significant reduction in the analgesia duration and the tramadol consumption in Group PNB compared with Group LA. The median VAS within the first 12 hours in PNB group was much lower (Z=-5.909, P< 0.001). The spasm of anal sphincter in Group PNB was less than Group LA in 48 hours after operation (t=10.502, P<0.0001); the satisfaction of the patients was higher in Group PNB (Χ²=8.531, P<0.05).

Ultrasound-guided PNB could provide good postoperative analgesia for PPH, and decrease the rate of urinary retention.