To evaluate high-frequency, high-intensity transcutaneous electrical nerve stimulation (TENS) as an inexpensive, noninvasive pain management approach for first-trimester aspiration abortion.
We conducted a noninferiority, single-blind, randomized controlled trial of patients seeking aspiration abortion at up to 83 days of gestation. Participants received TENS (placed posteriorly, T10-L1 and S2-S4) or intravenous (IV) sedation (fentanyl, midazolam). The primary outcome was pain with aspiration, as self-reported by visual analog scale (VAS, 100 mm). To detect at least a 15 mm mean difference on the 100 mm VAS with 90% power and a significance level of .05, a total of 90 participants were required.
Between January 2018 and October 2019, we enrolled 109 participants (55 TENS, 54 IV). Participant median gestation was 53 days (range 36–82) in the TENS group and 58 days (range 35–82) in the IV group (P=.65). Group demographics and clinical histories were similar. Intention-to-treat analysis (n=109) yielded noninferior results for the primary outcome (mean difference 4.8 mm, 95% CI −5.9 to 13.5 mm). In the per-protocol analysis, 9 (16%) in the TENS group were excluded after receiving IV sedation; 100 participants were included (46 TENS, 54 IV). Median (range) reported VAS for aspiration was 73 mm (13–97) and 66 mm (0–99) in the TENS and IV groups, respectively (P=.40). With a mean difference of 4.4 mm (95% CI −5.6 to 14.5 mm), we found TENS to be noninferior to IV. Physicians underestimated participant pain, perceiving pain to be 34 mm (6–91) in the TENS group and 25 mm (0–83) in the IV group (P=.003).
We found TENS to be a noninferior alternative to IV sedation for aspiration pain during first-trimester abortion. Expanding pain management options can improve quality of and access to abortion. Transcutaneous electrical nerve stimulation could be a standalone or adjunct approach for abortion pain management for those without access to or are ineligible to receive IV sedation due to the lack of sedation practitioner, designated driver, or local restrictions.
CLINICAL TRIAL REGISTRATION: