Transcutaneous electrical nerve stimulation (TENS) for pain control during first-trimester abortion: A single-blinded randomized controlled trial

Abstract

Introduction High-frequency, high-intensity transcutaneous electrical nerve stimulation (TENS), pulsating electrical currents that activate underlying nerves, is an inexpensive and non-invasive pain control approach. We sought to compare TENS to intravenous sedation (IV) for pain control in first-trimester surgical abortion. Method We conducted a non-inferiority, single-blinded, randomized controlled trial of participants undergoing surgical abortion up to 11 weeks’ gestation. Participants received TENS (electrodes parallel to the spinal cord at the T10-L1 and S2-S4 levels) or IV (100mcg fentanyl and 1mg versed). Providers administered the IV sedation and research staff administered the TENS and were therefore not blinded. The primary outcome was self-reported pain with aspiration (visual analogue scale, VAS 100mm, 0 “no pain” and 100 “worst pain imaginable”). Non-inferiority limit was defined as 15mm. We also assessed participant demographics and blinding. Results A total of 109 participants were enrolled (55 TENS, 54 IV) between January 2018 and October 2019. Participants had a mean gestational age of 56-days across groups (p = 0.88); groups were similar with regard to age, race and ethnicity, parity, and BMI. Nine (16%) in the TENS group were given IV sedation and excluded from the per-protocol analysis. 100 participants were included in the per-protocol analysis (46 TENS, 54 IV). Mean reported VAS for aspiration was 64.78 mm (SD24.16) and 60.35mm (SD26.06) in the TENS and IV groups, respectively, with a mean difference of 4.43mm (95% CI −5.6 to 14.47). One IV group participant received additional IV medications (2%). Post-procedure, in both groups the majority of participants identified their correct assignment (p = 0.96); one in five in both groups incorrectly identified their assignment (21.7%, n = 10 TENS; 22.2%, n = 12 IV). Intention-to-treat analysis (n = 109) yielded non-inferior results for the primary outcome. Conclusions TENS for pain control during first-trimester surgical abortion is non-inferior to IV sedation with respect to the primary outcome of pain with aspiration. TENS could be a pain control option for patients without access to IV sedation or for those who are ineligible to receive IV sedation due to additional cost, lack of sedation provider or restrictions, including the need for a designated driver. Expanding pain control options improves quality of care and access to abortion.