Transcutaneous Electric Nerve Stimulation for Analgesia During Outpatient Endometrial Biopsy: A Randomized Controlled Trial.

Abstract

To evaluate whether transcutaneous electric nerve stimulation (TENS) decreases pain at the time of outpatient endometrial biopsy. We conducted a randomized, double-blind trial of active TENS compared with placebo TENS at the time of endometrial biopsy. The primary outcome was pain measured on a 0- to 100-mm visual analog scale immediately after biopsy, with secondary outcomes including satisfaction and tolerability of TENS and pain scores at other procedural time points. To detect a 15-mm reduction in pain with a 30-mm SD, 80.0% power, and a significance level of 0.05, 64 participants were required in each arm. From December 2022 to December 2023, 135 participants were randomized with 67 in the placebo TENS arm and 68 in the active TENS arm. Baseline demographic and clinical characteristics were similar between groups. The median (interquartile range) pain score immediately after biopsy was 50 mm (20-80 mm) in the active TENS group and 60 mm (40-100 mm) in the placebo TENS group (P=.039). Pain scores at other time intervals were not statistically significantly different. In a subset analysis, participants with higher-than-median baseline anxiety had postprocedural pain scores (interquartile range) of 50 mm (40-80 mm) in the active TENS group compared with 80 mm (50-100 mm) in the placebo TENS group. Overall satisfaction (interquartile range) with pain control (with 100 mm representing completely satisfied) was 87.5 mm (60-100 mm) for active TENS and 70 mm (41-100 mm) for placebo TENS; 85.3% of active TENS participants would use TENS in a future endometrial biopsy. Minimal side effects were associated with TENS, with one participant reporting itching at the pad sites. Despite a statistical difference in pain scores, a clinical difference was not seen between active and placebo TENS for pain during endometrial biopsy. Satisfaction was higher in the active TENS group, and there were overall minimal side effects associated with TENS. ClinicalTrials.gov, NCT05472740.