Numbing the womb before an IUD cut placement pain in a Swedish trial
In 370 nulliparous women, instilling mepivacaine into the uterus before IUD placement lowered pain by about 15 mm on a 100-mm scale versus saline. It is a real effect, not a cure for the procedure.
| Group | Value (mm) |
|---|---|
| Intrauterine mepivacaine | 43.8 |
| Placebo saline | 58.6 |
Fear of pain is one of the reasons people give for not choosing an intrauterine device, and for those who have never given birth the placement can genuinely hurt. That fear is not trivial: it shapes contraceptive choices, and easing the procedure has been linked to better satisfaction and to patients feeling more in control of the decision [s1]. Clinicians have tried a range of local anaesthetics to blunt the pain, with mixed and often disappointing results — a lidocaine gel or a paracervical injection frequently fails to move the needle. A trial published in JAMA on 17 September tested a different approach: instilling anaesthetic directly into the uterine cavity before the device goes in [s1].
What the trial did
The study was a multicentre, double-blind, randomised, placebo-controlled trial at 11 outpatient gynaecology, maternal-health and youth clinics in Sweden, running from May 2021 through June 2024 [s1]. It enrolled nulliparous participants aged 18 to 31 who had chosen a smaller-diameter IUD — the 19.5 mg or 13.5 mg levonorgestrel devices or a copper IUD [s1]. A total of 370 people were randomised 1:1, 185 to each group [s1].
Two minutes before placement, participants received either 10 mL of mepivacaine at 20 mg/mL or 10 mL of sodium chloride at 9 mg/mL, delivered through a hydrosonography catheter into the uterus [s1]. Participants, clinicians and outcome assessors were all blinded to which they got [s1]. The primary outcome was the clinician-adjusted difference in pain during placement, scored on a 100-mm visual analog scale [s1].
What it found
The two groups were well matched, with a mean age of 21.7 years in each [s1]. Mean pain during placement was 43.8 mm (standard deviation 24.7) with mepivacaine and 58.6 mm (SD 21.5) with placebo saline — an unadjusted mean difference of 14.8 mm, with a 95% confidence interval of 10.0 to 19.6 and a P value below .001 [s1]. Adjusting for the individual clinician gave a near-identical result, a difference of 14.2 mm (95% CI 9.7 to 18.6) [s1]. The confidence interval sits well clear of zero, so this is a real reduction rather than a chance blip.
Tolerability moved in the same direction. Pain rated as tolerable was reported by 172 of 175 participants (98.3%) given mepivacaine and 159 of 174 (91.4%) given placebo, a relative risk of 1.08 (95% CI 1.02 to 1.13) and a number needed to treat of 15 (95% CI 9 to 43) [s1]. In other words, for every 15 people given the anaesthetic, roughly one more found the procedure tolerable than would have on saline alone.
How to read it
The result is positive and reasonably clean, but scale matters. A drop from a mean of about 59 mm to about 44 mm on a 100-mm scale is meaningful, yet it leaves the average participant still reporting placement pain in the middle of the range [s1]. Mepivacaine reduced the pain; it did not abolish it. The number needed to treat of 15 for "tolerable" pain says much the same thing — most people found the procedure tolerable either way, and the drug shifted a minority from just-intolerable to tolerable [s1].
The design is a strength worth naming. Blinding extended to the people scoring the pain, the comparator was an identical-looking saline instillation, and the trial was run across 11 clinics rather than a single specialist centre, which makes the effect less likely to be an artefact of one enthusiastic team [s1]. Mepivacaine is a long-established generic anaesthetic, and the report lists no commercial sponsor of the trial [s2].
The limits are equally clear. The findings apply to nulliparous people aged 18 to 31 receiving smaller-diameter devices; they do not automatically transfer to larger IUDs, to people who have given birth, or to older or younger patients [s1]. The instillation adds a step — a catheter and a two-minute wait — and the trial does not weigh that added time and cost against the pain reduction, nor does it report how the technique would fit an ordinary clinic's workflow [s1].
What to watch
The trial is registered on the EU Clinical Trials Register under EudraCT number 2020-002271-36, where the protocol and outcome definitions are logged [s2]. Whether intrauterine anaesthetic instillation becomes a routine option will depend on replication in broader populations and on whether the modest pain reduction is judged worth the extra step. For now the finding adds a genuine, evidence-backed tool to a field where most attempts to ease IUD placement pain have come up short.
Sources
- Intrauterine Mepivacaine Instillation vs Placebo for Pain During IUD Placement: A Randomized Clinical Trial — JAMA , September 17, 2026
- Pain relief at insertion of intrauterine device (EudraCT 2020-002271-36) — EU Clinical Trials Register
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