Pudendal Nerve Block for Posthemorrhoidectomy Pain: A Prospective, Single-Blinded Randomized Control Trial

BACKGROUND: Postoperative pain is common in hemorrhoidectomy patients. Local anesthetic given either as an intraoperative pudendal nerve block or as a local wound infiltration may help alleviate postoperative pain. OBJECTIVES: This study sought to determine whether the addition of an intraoperative pudendal nerve block to a perianal local wound infiltration and standardized analgesia regimen was superior to a perianal local wound infiltration and standardized analgesia regimen alone in reducing early postoperative pain following hemorrhoidectomy. The secondary objective was to measure differences between treatment groups in perceived perianal numbness, oral opioid requirements, and adverse events. DESIGN: This study was a prospective, single-blinded randomized controlled trial approved by the Eastern Health Human Research and Ethics Committee in Melbourne, Australia (registration number: E09/2014). SETTINGS: Patients were recruited across 3 Australian hospitals. PATIENTS: Eighty patients with symptomatic hemorrhoids requiring hemorrhoidectomy in colorectal surgical outpatient clinics were successfully recruited and enrolled in the study, with 1 patient later dropping out. INTERVENTION: Patients were randomly assigned to either the pudendal nerve block group or a control group. The pudendal nerve block group received 5 mL bupivacaine 0.5% with adrenaline 1:200,000 to both pudendal nerve trunks bilaterally. Both groups received 10 mL of the same local anesthetic injected into the post-hemorrhoidectomy wound bed. MAIN OUTCOME MEASURES: Visual analogue scales were used to record patient pain scores. Dichotomous (yes/no) answers were recorded for secondary objectives. RESULTS: There were no significant differences in postoperative pain between groups at 4 hours, 8 hours, 12 hours, or 24 hours. Additionally, there were no significant differences between groups with respect to perceived perianal numbness, oral opioid usage or adverse events. LIMITATIONS: The authors recognize that without a nerve stimulator, an argument can be made that the pudendal nerve block was not actually achieved. CONCLUSION: Pudendal nerve block does not appear to demonstrate additional benefit in post-hemorrhoidectomy pain reduction beyond local anesthetic to the wound.