Your doctor will insert an IUD with one or two thin strings hanging down into your vaginal canal. You should feel them with the tip of your fingers, but it’s very common not to. Use a backup form of birth control until you locate them or visit your doctor.

Can’t find your IUD string? You aren’t alone. As many as 18 percent of women with IUDs are unable to feel their strings, according to a 2011 review.

And chances are, everything is fine. There are a number of reasons why this may happen. Most aren’t cause for concern.

Keep reading to learn what may be to blame, symptoms you should watch for, and how your doctor may be able to help.

When your doctor inserted your IUD, they left one or two thin plastic strings hanging down into your vaginal canal. These strings are about 2 inches long — just long enough to be able to feel them with the tip of your finger. They feel like light fishing line.

However, many women are unable to feel these strings. This is usually nothing to worry about, but you should still use a backup form of birth control until you’re able to locate the strings or see your doctor.

You may be unable to feel the strings because:

The strings are up high in your vagina

You may not feel them because they were cut too short to reach.

The strings have coiled up into the cervix

Sometimes, the strings curl up next to the cervix. They may even be hidden in a fold of vaginal tissue. The strings may fall back into place during your next period, so make a note to check back then.

Expulsion

This occurs when your IUD falls out of your uterus. Although this isn’t common, it’s still possible. When it does happen, it’s usually during the first year of insertion.

In some cases, the IUD doesn’t fall out completely, so you may not find it in your underwear or toilet. If your IUD does come out, don’t try to put it back in. Make an appointment to see your doctor.

Perforation

This occurs when your IUD pokes into, or through, the wall of your cervix or uterus. Perforation is very rare. It only happens in only 1.4 per 1,000 (0.14%) hormonal IUD insertions and in 1.1 per 1,000 (0.11%) copper-IUD insertions, according to the American College of Obstetricians and Gynecologists. Your risk for perforation may be higher if you’ve recently given birth or are breastfeeding.

If your strings are simply out of reach or coiled into your cervix, you won’t have any symptoms. You should schedule a checkup with your doctor and use a backup form of birth control until then.

If you have a hormone-releasing IUD — such as Mirena, Liletta, Kyleena, or Skyla — your periods should get lighter and shorter. If your periods don’t change or if they return to normal after they’ve lightened, make an appointment with your doctor. Your IUD may have fallen out and you’ll have to get a new one. Be sure to use another form of birth control until your doctor gives the all clear.

Some symptoms may point to a bigger problem, like perforation, misplacement, or infection. See your doctor right away if you begin experiencing:

  • severe or prolonged cramping
  • fever or chills
  • abnormal blood, fluid, or odor coming from your vagina

If you can’t feel your IUD strings, your doctor will do a pelvic exam to see if the strings are still there. They may swirl a long cotton swab or cytobrush, the brush they use to collect a Pap smear, around the vagina and into the cervix to find the strings.

They may also use a magnifying device called a colposcope to get a better look.

If they can’t find the strings that way, they may perform an ultrasound. If the ultrasound doesn’t reveal your IUD placement, it’s most probable cause is that it was expelled through the vagina, and you may not have noticed. Your doctor may do an X-ray to be sure the IUD hasn’t perforated your uterus and traveled into your abdominal cavity.

If your IUD is in the proper position and you want to keep it, there’s no need to do anything else. If you want the IUD removed or if it’s out of position, your doctor will take it out.

If the IUD has perforated your uterus wall, you’ll have to have it surgically removed in the hospital.

But if it’s simply out of place or has partially expelled, your doctor will remove it during your appointment.

First, your cervix will be dilated, or opened. This can be done with a medication called misoprostol. It’s inserted into the vagina before the procedure.

Your doctor may also administer a pain reliever like ibuprofen to help prevent cramping. If additional pain relief is needed during the procedure, your doctor may inject a numbing medication into your cervix or apply a topical numbing gel.

Once your cervix has dilated, your doctor will use different instruments, like clamping forceps, to reach into your uterus and remove the IUD.

In most cases, you can have a new IUD inserted immediately after removal of the misplaced one.

Your IUD strings won’t stick out of your vagina like a tampon string. There should be just enough string hanging into your vaginal canal to feel with the tip of your fingertips.

You should check for your IUD strings with a clean finger once a month. A good time to do this is the day after your period ends.

If you’re unable to feel the strings, try to remain calm. Use backup contraception and give your doctor a call. They can help you locate your strings and advise you on any next steps.