The Effect of Pudendal Nerve Injection at the Time of Vaginal Surgery

Objectives: There is conflicting evidence regarding the effect of isolated pudendal nerve blockade at the time of vaginal surgery. Previous studies have compared pudendal nerve blockade to either normal saline placebo injection or no injection at the time of vaginal surgery demonstrating small or no difference between pain outcomes. However, no studies investigating nerve blocks at the time of vaginal surgery have sought to elucidate the effect of infiltration of the space around the pudendal nerve itself . The primary study objective was to determine if there is a difference in pain control among patients who received a pudendal nerve block, placebo pudendal nerve injection, and patients who received no pudendal injection at the time of vaginal surgery. Secondary objectives were to determine differences in postoperative opioid use and patient-reported satisfaction.

Methods: We performed a secondary analysis of patients procured from two randomized controlled trials at one institution investigating postoperative pain after vaginal pelvic reconstructive surgery. We compared the outcomes of three groups: control group who received no pudendal injection, intervention group who received bilateral pudendal nerve blockade, and placebo group who received bilateral normal saline pudendal injections. The primary outcome was postoperative pain scores using a visual analog scale. Secondary outcomes were opioid use, patient satisfaction, and postoperative complications. Linear mixed effects models were applied to the outcomes at all follow-up timepoints. Treatment effect estimates and 95% confidence intervals were estimated at each timepoint from the model. Continuous variables were also analyzed using Kruskal-Wallis rank sum tests at each timepoint.

Results: A total of 104 patients who underwent vaginal surgery were included for analysis: 36 pudendal nerve block (intervention group), 35 normal saline pudendal injection (placebo group), and 33 no injection (control group). The study groups were well-matched.
At all timepoints, VAS scores and patient satisfaction were equivalent among groups. Linear mixed effects models demonstrated no significant relationship between study group and time for postoperative pain severity scores, opioid use, and patient-reported satisfaction.

Conclusions: The three treatment groups did not differ in postoperative pain scores, opioid use, or satisfaction at all timepoints. Normal saline injection and no injection appear to have equivalent effect and can both serve as adequate placebo/ control for pudendal blockade at the time of vaginal surgery.