For a study, researchers sought to determine if high-frequency transcutaneous electrical nerve stimulation (hfTENS) lessened pain during a medication abortion. A randomized, placebo-controlled experiment was carried out. Participants who had a pharmaceutical abortion with mifepristone and misoprostol up to 70 days of gestation were given either active 80 Hz hfTENS or sham to use for a minimum of 60 minutes within 8 hours of misoprostol. The primary outcome was maximum pain on an 11-point numerical rating scale 8 hours after misoprostol. Researchers projected 20 per group with 80% power to detect a 2-point difference and 10% attrition. Secondary outcomes were the maximum pain score at 24 hours, the usage of extra analgesics, the difference in score before and after treatment, the experience of side effects, the result of abortions, and acceptability. They used real-time electronic questionnaires to gather data at the baseline, misoprostol (0-hour), 8-hour, and 24-hour intervals, as well as during the follow-up.

They screened 251 patients and randomized 40-20 each to hfTENS or sham—between June 2019 and March 2020, with one post-randomization exclusion and two patients lost to follow-up. The baseline features were comparable. At 8 hours, the median maximum pain ratings for hfTENS and sham were 7.0 (interquartile range 3.0) and 10.0 (interquartile range 3.0), respectively. When hfTENS users were compared to sham, the distribution of these scores was reduced (mean rank 15.17 vs 22.63, P=.036). High-frequency TENS users had a significantly lower post-treatment pain score (2.0 [interquartile range 2.5] vs 0 [interquartile range 1.5], P=.008). There were no statistically significant differences in the usage of supplemental analgesia, the distribution of maximum pain ratings at 24 hours, side effects, or acceptability assessments.

When compared to placebo, high-frequency TENS lowered maximum pain levels within 8 hours of misoprostol administration and pain scores immediately after therapy. High-frequency TENS is a nonpharmacologic pain treatment alternative during a medication abortion.