Cervical Insufficiency
(Cervical Incompetence)
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Connective tissue disorders that are present at birth and injuries can make tissues of the cervix weak.
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When the cervix is weak, the baby may be delivered too early.
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Cervical insufficiency is identified only after a woman becomes pregnant.
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To prevent early delivery, doctors may stitch the cervix closed (cerclage).
Pregnancy complications, such as cervical insufficiency, are problems that occur only during pregnancy. They may affect the woman, the fetus, or both and may occur at different times during the pregnancy. However, most pregnancy complications can be effectively treated.
Normally, the cervix (the lower part of the uterus) dilates only when labor starts, in response to contractions of the uterus. However, in some women, tissues of the cervix are weak. For unknown reasons, the cervix may open (dilate) long before the baby is due. As a result, the baby may be delivered too early.
If a woman has cervical insufficiency, she is likely to have it in future pregnancies.
Causes
What causes the cervix to be weak is not well understood. Usually, no specific cause can be identified.
The following may increase the risk of having a weak cervix:
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A connective tissue disorder present at birth (congenital), such as Ehlers-Danlos syndrome
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An injury to the cervix
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Birth defects of the uterus, including müllerian duct defects (for example, a uterus that is not shaped normally)
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Previous miscarriages during the 2nd trimester
The cervix may be injured during a previous delivery. It may also be injured when a large piece of tissue is removed from the cervix for a biopsy (called a cone biopsy) or when instruments are used to dilate the cervix (as can occur during dilation and curettage, or D & C).
Most women with cervical insufficiency do not have any of the above conditions.
Symptoms
Diagnosis
Cervical insufficiency is usually not identified until a woman delivers a baby too soon. It is suspected when a woman has had previous miscarriages during the 2nd trimester.
When doctors do routine examinations during pregnancy, they may suspect cervical insufficiency because the cervix has dilated too soon.
If cervical insufficiency is suspected, ultrasonography using a handheld device inserted inside the vagina (called transvaginal ultrasonography) is done. Findings during ultrasonography may suggest cervical insufficiency. For example, if ultrasonography shows that a woman has a short cervix, particularly a woman who is at risk of cervical insufficiency, doctors may closely watch for signs of premature labor.
Treatment
Doctors can place stitches around or through the cervix to keep it from opening too soon. Such procedures are called cervical cerclage.
Cervical cerclage is done during the 1st trimester if the risk of cervical insufficiency is high, as when a woman has had previous miscarriages during the 2nd trimester. Cerclage may be done before 24 weeks if doctors do not know what occurred in previous pregnancies but suspect that the woman had problems and if the woman has a short cervix.
Before cervical cerclage, the woman is given a general anesthetic or regional anesthetic. Then doctors usually insert instruments through the vagina to place the stitches. Stitches are usually removed before delivery. Occasionally, they are left in place, and cesarean delivery is done.
If preterm labor is suspected after 22 to 23 weeks of pregnancy, doctors may prescribe corticosteroids (to help the fetus's lungs mature) and modified bed rest (modified activity). Modified bed rest means that women should stay off of their feet most of the day.
