Incompetent Cervix – The Causes And How To Treat It

Incompetent Cervix – The Causes And How To Treat It

When a healthy pregnancy reaches full term (37 – 42 weeks) the cervix begins to thin and open (efface and dilate) so the baby can be born. When the cervix begins to open early, without contractions, in the second trimester, this is known as cervical insufficiency (or a weak or incompetent cervix). It can lead to late-term miscarriage or premature birth.

Hearing that you have a weak or incompetent cervix can leave women feeling as though their bodies aren’t working, and lead to feelings of failure.

If you have been diagnosed with cervical insufficiency, understanding this condition can help you cope.

Who Is At Risk For An Incompetent Cervix?

Cervical insufficiency occurs in about 1 in every 100 pregnancies and is responsible for about 25% of all second trimester losses. Women who experience this condition want to know what causes it and how to avoid it in future pregnancies.

For some women there is no known reason for cervical insufficiency. For others, it could be connected with one of the following risk factors:

  • Damage to the cervix during a difficult birth
  • Previous cervical surgery, such as cervical biopsy
  • Trauma to the cervix from a previous D&C (dilation and curettage)
  • Exposure to Diethylstilbestrol (DES), a synthetic form of the hormone estrogen, used from 1938 to the early 1980s to prevent miscarriage and pregnancy complications. Up to 30% of the daughters of women who took DES during pregnancy have reproductive tract problems.
  • One or more previous second trimester miscarriages with no known cause
  • Uterine or cervical malformations
  • Previous pregnancy with cervical insufficiency.

What Are The Symptoms Of An Incompetent Cervix?

Many women are either not aware of any changes to their cervix, or might dismiss mild symptoms as being related to normal pregnancy. Mild symptoms can begin between 14 and 20 weeks and include:

  • Backache
  • Pressure in the lower pelvic area
  • Mild cramps, similar to period pain
  • Vaginal discharge, which increases in amount or becomes watery
  • Light vaginal bleeding.

If you experience any of these symptoms, immediately contact your care provider, who will suggest a vaginal examination, and possibly an ultrasound, if it is suspected your cervix is changing.

It is difficult to screen for an incompetent cervix, but if you are at risk for it, your care provider might advise regular ultrasounds beginning at 16 weeks. These ultrasounds measure the length of your cervix and check for any signs it is beginning to thin and open.

These scans are usually done every two weeks until you are into the second trimester. If your cervix changes significantly, you are at high risk for premature birth and your care provider will recommend treatment.

How Is An Incompetent Cervix Treated?

The treatment for a cervix that is beginning to change is a procedure called a cerclage or cervical suture. This is a special stitch, which is put around your cervix, to keep it closed.

The procedure can be done either through the vagina (transvaginally, known as TVC) or through the abdomen (transabdominally, known as TAC).

There are several different types of stitch:

  • The McDonald stitch: this is the most commonly used stitch. It is woven in and out of the cervix, pulled tightly, and tied. Usually it is easily removed, and allows vaginal birth.
  • The Shirodkar stitch: this stitch can be removed near full term, or is permanent, requiring birth by c-section. The stitch begins at the 12 o’clock position, is worked through the cervix to the 6 o’clock position, and ends back at the 12 o’clock position on the other side of the cervix. The suture is pulled tightly and tied, to keep the cervix closed.
  • An abdominal stitch: this is used when there is not enough cervix to work with. The upper and lower parts of the cervix are stitched together, and a c-section is required.
  • The Hefner cerclage: this stitch is commonly used when cervical insufficiency is diagnosed late in pregnancy. This cerclage is removed closer to term.
  • The Lash cerclage: this stitch is the only type put in place before pregnancy. This stitch is used when there has been extensive cervical trauma or where there is a physical defect. The stitch is permanent and a c-section is required.

Once the cerclage is put in place, you will be told to rest for a few days. You might have some cramping and light bleeding in the days after the procedure. You might also have to refrain from exercise and from having sex for some time, or for the duration of your pregnancy.

If you experience any signs of infection, such as fever, burning, increased discharge with a smell, heavy bleeding or itching, contact your care provider immediately.

Can I Have A Cerclage?

Most women who have a cerclage in place are able to carry their babies to full term. In rare cases, the stitch does not prevent miscarriage or preterm birth.

There are women who can’t have a cerclage put in place, for the following reasons:

  • Cervix has already dilated 4cm
  • Membranes have already ruptured
  • There is increased irritation of the cervix.

There are risks in having a cervical cerclage. While rare, complications include:

  • Uterine rupture
  • Bladder rupture
  • Cervical laceration
  • Maternal haemorrhage
  • Preterm labour
  • Premature rupture of membranes.

It can be frightening to find out you have cervical insufficiency. It might make you feel anxious about your pregnancy, and worried your body is failing you, especially if your care provider uses the term ‘incompetent cervix’, which can make you feel as though your body is to blame for not cooperating.

If you give birth prematurely, you might feel guilty, or wonder whether you could have done anything to prevent it happening. It is important to remember that many cases of cervical insufficiency have no known cause. Talking to your care provider, partner or trusted friends might help you cope with your feelings.

Recommended Reading: Baby In The NICU? 17 Coping Tips For Parents.


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Sam McCulloch enjoyed talking so much about birth she decided to become a birth educator and doula, supporting parents in making informed choices about their birth experience. In her spare time she writes novels. She is mother to three beautiful little humans.

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