Trial Supports New Method for Easing IUD Insertion Pain

Intrauterine instillation of the anesthetic mepivacaine significantly reduced pain during intrauterine device (IUD) insertion, a Swedish randomized trial showed.

Mean pain score during IUD placement was 43.8 mm on a visual analog scale (range 0 to 100, with higher scores indicating worse pain) for patients who received mepivacaine administered via hydrosonography catheter versus 58.6 mm for those in the placebo group (P<0.001), reported Karin Elgemark, MD, of the Karolinska Institutet in Stockholm, and colleagues in JAMA.

Nearly all patients (98.3%) in the mepivacaine group said their pain was tolerable compared with 91.4% of the placebo group (relative risk [RR] 1.08, 95% CI 1.02-1.13). The number needed to treat for one patient to report tolerable pain was 15.

“Considering the frequency of IUD placements worldwide, even modest reductions in the proportion of individuals experiencing intolerable pain may have important clinical implications,” Elgemark and team wrote.

Of note, 79% of patients who received mepivacaine said they’d recommend the pain relief method to others versus 68.6% of the placebo group (RR 1.15, 95% CI 1.01-1.31).

Nikki Zite, MD, MPH, an ob/gyn at the University of Tennessee Graduate School of Medicine in Knoxville, told MedPage Today that “patients benefit from knowing providers are concerned and trying to address their pain, even if they don’t receive actual pain medication.”

In recent years, patients have increasingly reported pain during IUD insertion, including on social media. The CDC has urged physicians to counsel their patients about possible pain associated with IUD placement, while the American College of Obstetricians and Gynecologists has called for clinicians to discuss pain management options.

In another study also published in JAMA, one in five IUD insertion patients universally offered intravenous moderate sedation received it, indicating that a desire for pain control may be more prevalent than previously thought.

Zite noted that studying IUD insertion pain is hard because it involves multiple steps. Some people, for instance, find the speculum and the tenaculum used to manipulate the uterus painful.

“The strategy these authors were investigating to manage pain would have no impact on speculum or tenaculum placement and it was not asked about during the assessment,” she pointed out.

Previous studies have assessed intracervical/intrauterine lidocaine gel, intracervical injections, and paracervical blocks as pain control methods, but Elgemark and team were interested in a minimally invasive approach. Some of the authors had previously conducted a small pilot trial using 1% intrauterine mepivacaine for IUD insertion pain relief, and based on those findings, bumped the concentration to 2% mepivacaine and designed this trial to evaluate the effect more robustly.

This double-blind trial took place from May 2021 to June 2024 at 11 outpatient gynecology, maternal health, and youth clinics across Sweden. Eligible patients had never given birth, were ages 18 to 31, and were opting for a copper IUD or a 19.5-mg or 13.5-mg levonorgestrel-releasing hormonal IUD. People with ongoing pregnancies and those replacing their IUDs were excluded, as were those with pelvic infections or allergies to local anesthetics.

In all, 370 patients (mean age 21.7) were randomly assigned 1:1 to either intrauterine instillation of 10 mL of mepivacaine (20 mg/mL) or to sodium chloride (9 mg/mL). Both were administered via hydrosonography catheter 2 minutes before IUD placement. Mepivacaine was chosen over lidocaine because of faster onset and less potential toxicity.

IUDs were placed by gynecologists and midwives. Elgemark noted that clinicians received a theoretical presentation, but not practical training, on how to use the catheter, and that the equipment used is common in gynecology clinics.

The authors acknowledged some limitations to their study. It was not designed to shed light on the relative efficacy of mepivacaine versus other pain relief approaches, and it didn’t account for clinician-assessed IUD placement difficulty or patient anxiety.

While the study is well designed for its target outcome, Zite said some institutional review boards in the U.S. may have had concerns about “essentially not providing any pain management in the name of research for a procedure we routinely offer various pain management options for.”