Transcutaneous electrical nerve stimulation for pain management during intrauterine device insertion: a randomized controlled trial.

BACKGROUND

Pain during intrauterine device (IUD) insertion is a significant patient concern. Current pharmacologic strategies inadequately address procedural pain, highlighting the need for rigorous evaluation of novel approaches.

OBJECTIVE

To evaluate whether high-frequency transcutaneous electrical nerve stimulation (TENS) reduces pain with IUD insertion.

STUDY

DESIGN

We conducted a double-blind randomized controlled trial in which 98 participants undergoing LNG 52 mg or CuT380A IUD insertion received either active high-frequency TENS or sham TENS. We measured pain using a 100-mm visual analog scale (VAS) at multiple time points during the procedure. The primary outcome was pain at the time of IUD insertion. Participants completed a pre-procedure survey asking about demographic and reproductive characteristics, anticipated pain, and anxiety. We asked participants post-procedure about satisfaction with pain during procedure and the TENS device. Clinicians completed a post-procedure survey asking about their perception of participant pain and ease of insertion. We estimated a total sample size of 98 to achieve 80% power to detect a 20 mm difference in pain scores, with 10% attrition/protocol deviation and 15% inflation to account for nonparametric distribution. We performed an intention-to-treat analysis and calculated mean pain scores and standard deviations. We used t-tests to compare mean pain scores at the time of IUD insertion and chi-square tests to compare categorical variables. We dichotomized parity as nulliparous (no prior delivery) vs. parous (any delivery greater than 20 weeks).

RESULTS

Between March 2024 and April 2025, we screened 150 participants and enrolled 99 individuals (active n=49; sham n=50) with one post-randomization exclusion. Baseline characteristics were similar, with a median age of 29 years and just over half having had a previous birth (53.1%). Pain at the time of IUD insertion did not differ between active and sham TENS groups (50.8 ± 26.9 mm vs 50.6 ± 29.2 mm; p=0.97). We also observed no differences in procedure duration. Nulliparous participants reported higher pain scores overall compared to parous individuals, but we detected no difference in pain scores relative to treatment intervention within groups (nulliparous - active 58.8 ± 28.7 mm, sham 59.3 ± 25.5 mm, p=0.95; parous - active 43.5 ± 23.3 mm vs. sham 43.2 ± 30.6, p=0.97). While clinician estimates and participant-reported maximum-pain scores were mildly correlated (Pearson's correlation coefficient = 0.41), there was a significant difference between mean clinician-estimated and participant-reported maximum pain scores (p<0.001), 48.9 ± 26.8 mm vs. 60.5 ± 25.2 mm, respectively. Participants undergoing IUD insertions perceived as difficult by clinicians reported higher mean pain scores than those perceived as easy (71.6 ± 24.2 mm vs. 56.0 ± 24.4 mm, respectively; p=0.006).

CONCLUSION

High-frequency active TENS did not reduce pain during IUD insertion compared with sham TENS. These findings were not affected by parity.