Numbing the cervix cut IUD-insertion pain in a trial, but the technique matters

Injecting local anaesthetic around the cervix before an intrauterine device is placed reduced the pain of the procedure in a double-blind randomised trial, cutting the median global pain score to 30 mm on a 100 mm scale against 45 mm with a sham needle [s1]. The benefit was clearest in women who had never given birth [s1] — but a separate 2026 meta-analysis is a reminder that not every numbing method, or every drug, delivers the same result [s2].

Why this is being studied now

Pain at IUD insertion has moved from a dismissed complaint to a research priority, after years in which patients reported being told to expect only "a pinch." IUDs are among the most effective reversible contraceptives, so anything that deters people from choosing or keeping one has a real cost, and fear of the insertion is one such deterrent. The open question was never whether local anaesthetic can numb tissue — it can — but whether a specific, practical technique measurably lowers the pain of this specific procedure in a properly controlled trial. Two 2026 papers in Contraception test exactly that, and they do not test the same thing.

The trial: a paracervical block

The randomised trial compared three arms — a paracervical block of 1% lidocaine with epinephrine 1:100,000, 10 mL; a saline injection; or a capped needle that mimicked the sensation of an injection without delivering one — under double-blind conditions, with patients enrolled from June 30, 2022, to August 16, 2024 [s1]. The primary outcome was a global pain score on a 100 mm visual-analogue scale [s1]. It included 246 patients, 82 per group [s1].

Women who received the block reported a lower median global pain score during placement (30 mm, interquartile range 10–50) than those given a saline injection (45 mm, IQR 25–60) or the capped needle (45 mm, IQR 20–70), with p = 0.003 and p = 0.001 respectively [s1]. Among participants who had never given birth — the group that consistently reports the most pain — the block again lowered scores (median 40 mm, IQR 25–53) against saline (50 mm, IQR 30–68) and the capped needle (60 mm, IQR 33–70), p < 0.001 [s1].

Two secondary findings matter for the practicality of the technique. The injection itself was reported as barely painful, a median of 1 out of 10 (IQR 0–2), and patients in the block group were more satisfied than those given the sham, p < 0.01 [s1]. That the saline injection landed at the same median as the capped needle [s1] suggests the relief came from the anaesthetic, not from the act of injecting.

The meta-analysis: route and drug decide the answer

The second paper pools the wider literature, but on a different technique: intrauterine anaesthesia, meaning anaesthetic instilled into the uterine cavity rather than injected around the cervix [s2]. It included six randomised trials of 651 women, 68% of whom had never given birth, comparing intrauterine anaesthesia against a saline infusion [s2].

Across the five trials (427 women) that reported pain during insertion, intrauterine anaesthesia beat placebo, but modestly — a standardised mean difference of −0.47 (95% CI −0.90 to −0.03; p = 0.04), with substantial heterogeneity between studies (I² = 58%) [s2]. The interesting split is in the subgroups: the two lidocaine trials (262 women) showed a clear reduction (p = 0.0002), while the two trials using other anaesthetic agents (165 women) showed no significant effect (p = 0.27) [s2]. Pain after insertion did not differ significantly between groups (p = 0.05) [s2].

The caveat both papers share

The meta-analysis carries an honest limitation its authors flag directly: every included trial compared an anaesthetic infusion against a saline infusion, not against no infusion at all, so the true analgesic effect of intrauterine anaesthesia — as opposed to the act of instilling fluid — remains uncertain [s2]. The randomised trial partly sidesteps this by including a capped-needle arm alongside the saline one [s1], which is why its design is the stronger of the two for isolating the drug's effect.

Taken together, the two papers point the same way without being interchangeable: lidocaine specifically, and a paracervical block in particular, has the best-supported case, and the people most likely to benefit are those who have never given birth [s1][s2]. Neither study establishes that any one approach should be routine for everyone, and both are about a clinical procedure performed by a provider — this is trial evidence, not a how-to, and not medical advice. For where IUDs sit among contraceptive options, see our comparison of typical- versus perfect-use effectiveness.

What to watch

Whether professional guidance moves from counselling patients about pain options toward recommending a specific technique, and larger trials that compare a paracervical block head-to-head against intrauterine lidocaine rather than against saline [s1][s2].

Sources

• A double-blind, triple-arm randomized controlled trial of 1% lidocaine paracervical block for intrauterine device (IUD) insertion — Contraception, 2026-01-24
• Effectiveness of intrauterine anesthesia on pain management during IUD insertion: A meta-analysis of randomized controlled trials — Contraception, 2026-04-20