Cervical incompetence

Overview
In medicine, cervical incompetence is a condition in which a pregnant woman's cervix begins to dilate (widen) and efface (thin) before her pregnancy has reached term. Cervical incompetence is a cause of miscarriage and preterm birth in the second and third trimesters.

In a woman with cervical incompetence, dilation and effacement of the cervix occur without pain or uterine contractions. Instead of happening in response to uterine contractions, as in normal pregnancy, these events occur because of weakness of the cervix, which opens under the growing pressure of the uterus as pregnancy progresses. If the changes are not halted, rupture of the membranes and birth of a premature baby can result. According to statistics provided by the Mayo Clinic, cervical incompetence is relatively rare in the United States, occurring in only 1—2% of all pregnancies, but it is thought to cause as many as 20—25% of miscarriages in the second trimester.

Risk Factors
Risk factors for premature birth or stillbirth due to cervical incompetence include:


 * diagnosis of cervical incompetence in a previous pregnancy,
 * previous preterm premature rupture of membranes,
 * history of conization (cervical biopsy),
 * diethylstilbestrol exposure, which can cause anatomical defects, and
 * uterine anomalies.

Repeated procedures (such as mechanical dilation, especially during late pregnancy) appear to create a risk. Additionally, any significant trauma to the cervix can weaken the tissues involved.

Treatment
Cervical incompetence is not generally treated except when it appears to threaten a pregnancy. Cervical incompetence can be treated using cervical cerclage, a surgical technique that reinforces the cervical muscle by placing sutures above the opening of the cervix to narrow the cervical canal.

Cerclage procedures usually entail closing the cervix through the vagina using a speculum. Another approach involves performing the cerclage through an abdominal incision. Transabdominal cerclage of the cervix makes it possible to place the stitch exactly at the level that is needed. It can be carried out when the cervix is very short, effaced or totally distorted. The complications described in the literature have been rare: hemorrhage from damage to the veins at the time of the procedure; and fetal death due to uterine vessels occlusion.

Note: The first revision of this article was adapted from material from the public domain source "Summary Report: ICD-9-CM coordination and maintenance committee", published at http://www.cms.hhs.gov/paymentsystems/icd9/icd111700.pdf.