Cervical Incompetence

Cervical Incompetence

When the cervix shortens and opens in the second trimester (16 to 24 weeks) or early in the third trimester without any other symptoms of labour it may be referred to as cervical incompetence or cervical insufficiency.

The cervix is the canal at the base of the womb (uterus) that connects it to the vagina. It is also known as the neck of the womb. When a pregnancy reaches full term the cervix begins to shorten (efface) and open (dilate), allowing the baby to be born. This is part of the normal labour and birth process.

When the cervix shortens and opens in the second trimester (16 to 24 weeks) or early in the third trimester without any other symptoms of labour it is sometimes referred to as “cervical incompetence” as this term is sometimes used incorrectly instead of “preterm birth”. True cervical incompetence, in which there is a structural problem with the cervix, is uncommon and most women who have a preterm birth will not have any problems in their following pregnancies, even without treatment.

What we discuss here is the cases in which there is a structural weakness in the cervix that caused preterm birth.

Structural cervical problems that are linked to premature birth

  • You may have undergone treatment for cervical cancer or precancerous cells such as trachelectomy (surgical removal of the cervix), LLETZ procedures or cone biopsy. In some cases, quite a lot of cervix may have been removed and it is a good idea to ask your gynaecologist whether more than 1 cm of tissue was removed.
  • You may have experienced previous obstetric cervical trauma, such as cervical tearing during labour or prior dilation and curettage (D&C). This involves opening the cervix and surgically removal of part of the lining of the uterus and/or contents of the uterus, for example carried out after a first trimester miscarriage or abortion.
  • You may have undergone a full or partially dilated emergency caesarean section in a previous pregnancy and had damage to the top of your cervix during the delivery of your baby.
  • You may have been born with a connective tissue disorder such as hypermobility or ehlers danlos syndrome, which effects the collagen within the tissues of the cervix causing it to be weak.
  • You may have been exposed to DES (Diethylstilbestrol) in the womb. DES was given to women up until 1971 as it was thought to prevent miscarriage but it has since been linked with issues of the reproductive system and preterm birth in those whose mother’s took it while pregnant.
  • You may have a uterine abnormality. Uterine abnormalities have not been shown to affect the structure of the cervix but they are linked to preterm birth.
  • You may have been born with a naturally weak or short cervix and this may be genetic .

If your cervix has been found to measure less than 25mm’s (2.5cm) during pregnancy it is a cause for concern and you should be treated as high risk for preterm birth. You may need treatment. You should also be monitored closely during future pregnancies.

Symptoms of cervical incompetence in pregnancy

There are no obvious symptoms you can look out for of the cervix opening too soon, whether this is due to cervical incompetence or other causes. Your cervix can shorten and dilate without any other signs.

If you have been told you are at risk of premature birth or you have any of the cervical problems listed above, it is important that you are monitored regularly in your pregnancy. This will include checks on the length of your cervix.

A pregnancy that has a risk of premature birth can be very scary. If at any time you are worried about any signs or symptoms you are experiencing; then you should contact your midwife immediately.

Look out for the symptoms below that could indicate premature labour.

  • an increase in pelvic pressure within the vagina or rectum.
  • an increase in discharge and/or a gush/repeat trickling of fluid, which could mean your waters have broken (preterm premature rupture of membranes).
  • bleeding or losing your mucus plug.
  • period type pains in your abdomen or lower back. These may have a rhythm or be constant.

Do I have cervical incompetence?

You are at higher risk of having cervical incompetence if you:

  • have previously had one or more premature births or miscarriages during the second or early third trimester
  • have any of the factors listed above.

·         A note on intrauterine infection and preterm birth

  • If you had an intrauterine infection(chorioamnionitis) in a previous premature birth, it is important to ensure your consultant considers the cervical problems listed above rather than assuming infection was the cause of the birth.
  • When a woman gives birth early the cervix shortens some time before birth. This allows bacteria (which are normally present in the vagina) to move up into the womb, which can develop into an infection.
  • Therefore it is very possible that it is the short cervix that allowed the infection to develop, rather than the infection causing the cervix to shorten and open.

Treatment for cervical incompetence

If your doctor thinks you are at risk of cervical incompetence or premature birth the length of your cervix will be monitored and if it is found to be short, treatment will be focused on prolonging your pregnancy.

You will have regular monitoring during your pregnancy with:

  • transvaginal scans (an ultrasound wand that is inserted into the vagina to give the best view of the cervix length)
  • vaginal swabs for markers of preterm birth (for example fetal fibronectin – a substance that is only present in the vagina when you are at increased risk of going into early labour)

This monitoring can be reassuring, or else can predict an increased chance of early delivery, before you are able to detect any symptoms yourself. It should start between 14-16 weeks of pregnancy.

Some consultants may also recommend antibiotic treatment to try and reduce the risk of infection, for example an antibiotic pessary that is inserted for one week of each month to try and prevent an infection happening. There is no evidence currently to support that this practice reduces the risk of early delivery.

If you are at very high risk of giving birth prematurely with cervical incompetence, the most common treatment is a stitch / cerclage, and vaginal progesterone are also recognised treatments for a short cervix.

Women without cervical incompetence but who have other risk factors for premature birth or whose cervix is shortening for other reasons may also benefit from the cervical stitch.

Through our Center we follow-up to periodically to measure the cervical length by vaginal ultrasound and examine the cervix and  cervical swabs will performed before and during pregnancy

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