News · Heart & Metabolic
IUD placement hurt less with a numbing solution in the uterus, in a 370-person trial
Fear of the pain puts many people off an IUD. A Swedish trial found that rinsing the uterus with a local anesthetic two minutes beforehand took a real edge off it.
- A randomized, double-blind trial in 370 people aged 18 to 31 who had never given birth.
- Half had a local anesthetic rinsed into the uterus two minutes before the IUD went in; half had salt water.
- Average pain was about 44 out of 100 with the anesthetic against about 59 with salt water.
- 98% found the pain tolerable with the anesthetic, against 91% without it.
- It eased the pain rather than removing it, and it has only been tested in this group.
Intrauterine devices are among the most effective forms of contraception available, and one of the main reasons people turn them down has nothing to do with how well they work. It is the fitting. Accounts of painful IUD placement circulate widely, and the fear alone steers some people toward methods they like less.
A Swedish trial published in JAMA tested a simple answer in 370 people who had never given birth: rinse the inside of the uterus with a local anesthetic two minutes before the device goes in. Pain scores dropped by about a quarter.
What an IUD placement involves
MedlinePlus describes the IUD as a small, T-shaped device that a provider inserts into the uterus, and notes that IUDs can last from 3 to 10 years. That long life is much of the appeal.
Placement means passing a thin tube through the cervix, the narrow opening of the uterus, and the uterus often responds by cramping. For people who have never been pregnant the cervix is tighter, which is why this group tends to report the most pain. The authors note that concern about pain during intrauterine device placement is common and reduces selection of an IUD.
How the numbing trial was run
The design is as clean as these trials get. Participants were randomly assigned to intrauterine instillation of 10 mL of mepivacaine or sodium chloride via a hydrosonography catheter, meaning either a local anesthetic or plain salt water was rinsed into the uterus through a thin tube two minutes before placement.
Participants, clinicians, and outcome assessors were blinded to treatment allocation. Nobody in the room knew who had the real drug, which matters enormously for an outcome as subjective as pain. Everyone was aged 18 to 31, had never given birth, and was having one of the smaller IUDs fitted.
What the anesthetic changed about the pain
On a scale running from no pain at 0 to the worst imaginable at 100, the difference was clear. Mean pain score during IUD placement was 43.8 mm in the mepivacaine group and 58.6 mm in the placebo group, a gap of about 15 points.
The tolerability result is arguably the one that matters more. Tolerable pain was reported by 172 of 175 participants in the mepivacaine group and 159 of 174 in the placebo group. Put another way, roughly one person in eleven without the anesthetic found the experience intolerable, against about one in sixty with it.
Why a modest drop in IUD pain still matters
A 15-point change will not make anyone describe the procedure as pleasant, and the anesthetic group still averaged in the middle of the scale. This takes the edge off. It does not remove the discomfort, and nobody reading the result should expect a painless fitting. But the decision this study speaks to is made before the appointment, not during it. If fear of the fitting is what keeps someone from a contraceptive they would otherwise prefer, a method that meaningfully lowers the odds of an intolerable experience changes the calculation, and it does so with a drug that has been in use for decades.
What a trial of first-time IUD users cannot tell us
Everyone here had never given birth and was fitted with a narrower device. Whether the same rinse helps people who have given birth, or those having larger devices placed, was not tested.
The trial was also run in Swedish clinics with a standard technique, and pain relief for IUD placement varies a great deal between countries and even between clinics. The study measured pain during placement itself, not the cramping that can follow for hours afterward.
What this changes for people considering an IUD
The practical step is a conversation, not a demand for a specific drug. Asking what pain relief a clinic offers for placement is entirely reasonable, and this trial adds a well-tested option to a list that has often been short.
For clinicians, the finding is that a cheap, familiar anesthetic, delivered the right way, made a measurable difference in the patients who find placement hardest. For patients, it is evidence that the pain of an IUD fitting is a problem being worked on, rather than something to be endured.
People also ask
What did the study find?
Mean pain score during IUD placement was 43.8 mm in the mepivacaine group and 58.6 mm in the placebo group (mean difference 14.8 mm, 95% CI 10.0-19.6). Tolerable pain was reported by 98.3% in the mepivacaine group and 91.4% in the placebo group.
What is mepivacaine?
A local anesthetic, in the same family as the drugs dentists use to numb a tooth. Here it was rinsed into the uterus through a thin tube two minutes before the IUD was placed.
Who was in the trial?
People aged 18 to 31 who had never given birth, which is the group that tends to find placement most painful, choosing either hormonal or copper IUDs with narrower insertion tubes.
How big is a 15-point drop on a 100-point scale?
Noticeable but not dramatic. Pain went from a little over half the scale to a little under half. It is best read as taking the edge off, not as painless placement.
Can I ask for this?
It is reasonable to ask your clinician what pain relief they offer for IUD placement. Whether this particular method is available depends on where you are. This is general information rather than medical advice.
Does it work for people who have given birth?
It was not tested in them. People who have given birth generally find placement less painful, so the size of any benefit could be different.