Efficacy and safety of pudendal nerve block for postoperative analgesia of hemorrhoids: a systematic review of 7 randomized controlled trials

Pudendal nerve block (PNB) is one of the common anesthesia methods, which has been widely applied in postoperative analgesia of hemorrhoids in recent years. To analyze the effectiveness and safety of PNB on postoperative analgesia of hemorrhoids, we conducted a systematic review of 7 randomized controlled trials (RCT) searched from PubMed, Embase, Web of Science, the Cochrane Central Register of Controlled Trials (CENTRAL), the China Network Knowledge Infrastructure (CNKI), the Wan Fang Database and Chinese Biomedicine (CBM), which were published before 7th September, 2020, and involved a total of 560 participants. We evaluated the function of PNB in improving outcomes of postoperative analgesia of hemorrhoids. Visual analogue scale (VAS) scores on postoperative 6, 12, 24, 48 h and the first time of defecation were enhanced by the application of PNB. The incidence of urinary retention, the need for analgesics [odds ratio (OR), 0.11; 95% CI, 0.04-0.37; P=0.0003] and the incidence of side effects (OR, 0.12; 95% CI, 0.04-0.39; P=0.004) in patients receiving PNB were lower than those of controls. In addition, there was no significant difference in the incidence of bleeding between groups. PNB could effectively relieve postoperative pain of hemorrhoids and reduce complications without increasing the incidence of side effects. Our results still need to be confirmed by high-quality, multi-center clinical studies.