Connective tissue disorders that are present at birth and injuries can make tissues of the cervix weak.
When the cervix is weak, the baby may be delivered too early.
Cervical insufficiency is identified only after a woman becomes pregnant.
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. As a result, the cervix may open (dilate) long before the baby is due, and the baby may be delivered too early.
If a woman has cervical insufficiency, she is likely to have it in future pregnancies.
What causes the cervix to be weak is not well-understood. Usually, no specific cause can be identified.
Conditions that increase the risk of having a weak cervix (risk factors) include
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 (D & C).
Most women with cervical insufficiency do not have any of the above conditions.
Cervical insufficiency is usually not identified until a woman delivers a baby too soon.
Doctors suspect cervical insufficiency when a woman has risk factors for a weak cervix, such as previous miscarriages during the 2nd trimester.
Doctors may also suspect cervical insufficiency during a routine examination during pregnancy when they see that 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.
Doctors can place stitches around or through the cervix to keep it from opening too soon. Such procedures are called cervical cerclage.
Cerclage appears to prevent preterm delivery in women who have had two more miscarriages during the 2nd-trimester. In such women and other women who have a high risk of cervical insufficiency, cerclage is done during the 1st trimester. Cerclage may also be done before 24 weeks (by the end of the 2nd trimester) if doctors do not know what happened in previous pregnancies but suspect problems in a woman who has a short cervix.
For other women, doctors try to use cerclage only when women have all of the following conditions:
Limiting cerclage to these women does not appear to increase the risk of preterm delivery and reduces the number of cerclages currently being done by two thirds.
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.