Swedish Study Shows Anesthetic Instillation Reduces IUD Placement Discomfort
A randomized trial in Sweden found that delivering the anesthetic mepivacaine directly into the uterus via a catheter significantly lowered pain scores during IUD insertion compared with placebo. Nearly 80% of patients receiving the drug said they would recommend the method, and the number needed to treat for one patient to report tolerable pain was 15. The authors note that even modest pain reductions could have broad clinical impact given the frequency of IUD placements worldwide.
The double-blind trial ran from May 2021 to June 2024 at 11 Swedish gynecology, maternal health, and youth clinics. Participants were nulliparous women aged 18-31 choosing copper or levonorgestrel hormonal IUDs; those with pelvic infections, local anesthetic allergies, or ongoing pregnancies were excluded. The 2% mepivacaine concentration represented an increase from the 1% used in the research group's earlier pilot work.
Patients receiving the drug showed a mean pain score roughly 15 mm lower on the 100-mm scale, and the number needed to treat for one additional patient to report tolerable pain was 15. The technique does not address pain from speculum or tenaculum placement, which some patients experience separately. Prior research has explored lidocaine gels, intracervical injections, and paracervical blocks for similar purposes.
This study could reshape clinical protocols for IUD insertion, potentially making intrauterine anesthetic instillation a standard offering. Since IUDs are used worldwide, even modest pain improvements may increase patient comfort and contraceptive uptake. However, the approach requires additional equipment and training, and its applicability to broader populations—including those who have given birth—remains uncertain. The findings may also encourage further research into minimally invasive pain management for gynecologic procedures.