Incompetent Cervix

An Incompetent cervix in pregnancy, is also called cervical insufficiency (or cervical weakness).

Before pregnancy your cervix, which is the lower part of your uterus at the top of the opening to your vagina, remains tightly closed.  In pregnancy the majority of women will carry their babies to full term, without complication.  At the time of labour in a normal full term pregnancy, your cervix dilates until it reaches 10cm, and then your baby is delivered.  Unfortunately Patients with an incompetent cervix, will often begin to dilate very early in their pregnancy, leading to late miscarriage or premature birth and/or loss of an otherwise healthy pregnancy.  It is estimated that approximately 1 in 1000 pregnant women will suffer with cervical insufficiency. Patients who have had excision of the transformation zone of the cervix for treatment of cervical CIN, are considered  to be at a “higher risk”.

The difficulty with this condition is that it will not necessarily become apparent that a patient has cervical incompetence until she suddenly develops symptoms of a light vaginal bleeding or spotting, very early Braxton hicks like contractions, a change in vaginal discharge, or a sensation of pelvic pressure.  This “generally” occurs in the second trimester of the pregnancy, which is between 13 & 28 weeks gestation.

If you do experience these symptoms at or around this gestation, you need to report immediately to your Obstetrician. Your Obstetrician will perform a vaginal examination and check to see if your cervix is dilated, and if there are signs that the amniotic sac has begun to protrude through the opening (prolapsed fetal membranes). Your Obstetrician may also use transvaginal ultrasound to evaluate the length of your cervix.

The pregnancy outcomes with this condition can vary. If minimal dilation has occurred, strict bed rest and close observation for infection may suffice. If the incompetency becomes apparent early enough, a Cervical Cerclage (cervical stitch) may be performed by a Specialist Obstetrician. This is often referred to a Shirodkar suture, where the cervix is sutured tightly closed in an effort to prolong the pregnancy until the fetus is mature enough to survive. The suture will be removed by your Specialist just prior to your pregnancy coming to term, or at the time of a Caesarean Section. Whilst this can be a very effective treatment, it is not always a possibility and is assessed relative to the patient’s individual situation.

In patients who have had early pregnancy loss due to cervical insufficiency, a stitch may be placed early in a subsequent pregnancy in a controlled environment to try to avoid a similar emergency in that current pregnancy.

A/Prof. John Pardey, Dr Sarah Pixton and Dr Maree Wallwork all specialise in “high risk” pregnancy are, and all perform cervical cerclage if required.

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