Incompetent Cervix

As your pregnancy progresses and your baby grows larger and heavier, an increasing amount of pressure is placed on your cervix. In some women, this may cause their cervix to efface and dilate without contractions, a condition called cervical insufficiency or an incompetent cervix that can lead to miscarriage, preterm rupture of the membranes, premature delivery, and early preterm delivery (before 32 weeks). While an incompetent cervix occurs in only 1 out of 100 pregnancies, the condition is responsible for approximately 25 percent of miscarriages in the second trimester.

Your cervix is the narrow, tubular, lower end of the uterus that extends into the vagina. When you're not pregnant, your cervix remains open a tiny bit to allow sperm to enter the uterus and menstrual blood to flow out. However, once you become pregnant, secretions fill the canal and form a protective barrier called the mucous plug. During a normal pregnancy, the cervix remains firm, long, and closed until late in the third trimester when it usually begins to soften, efface (grow shorter), and dilate (open up) as your body prepares for labor. With an incompetent cervix, the amniotic membranes surrounding the fetus bulge down into the opening of the cervix until they break, resulting in the loss of the baby or a very premature delivery.

Generally, there are no symptoms associated with an incompetent cervix and few women realize they have the condition until they miscarry - usually four months into their pregnancy or later. Symptoms of a miscarriage due to an incompetent cervix include abdominal pressure and feeling a "bump" in the vagina. If you have an incompetent cervix with one pregnancy, you will have to take precautions with all subsequent pregnancies.

The causes of an incompetent cervix are not always known; some women are just born with an unusually short or soft cervix. However, you're more likely to have this condition if:

• Your cervix was injured during a previous birth or dilation and curettage (D&C), or you've had several pregnancies terminated.
• You've had a previous miscarriage in the second trimester that had no identifiable cause, or an early spontaneous preterm delivery that was not caused by preterm labor or a placental abruption. Your risk increases if you've had more than one late miscarriage or early spontaneous preterm birth.
• Your mother took the drug DES while she was pregnant with you.
• You've had a cone biopsy or LEEP (Loop Electrosurgical Excision Procedure). These are generally done to treat cervical dysplasia, a precancerous change in the skin on the cervix.

To diagnose an incompetent cervix, your doctor may perform either a manual exam or an ultrasound. If these show your cervical opening is greater than 2.5 cm, or the length has shortened to less than 20 mm, and you're less than 24 weeks pregnant, your doctor may recommend you have a cervical cerclage, a procedure in which a band of strong thread is stitched around your cervix to reinforce it and help hold it closed. Cerclage successfully treats incompetent cervix 85 to 90 percent of the time, especially if performed early in a pregnancy. The best time to perform a cerclage is between 13 and 16 weeks, before the cervix starts to change.

While cerclage can save the baby's life in many instances, it also has potential risks and may cause preterm delivery, infection, uterine rupture, maternal hemorrhage, bladder rupture, cervical laceration, preterm labor and premature rupture of the membranes. However, the likelihood of these complications occurring is minimal and most health care providers feel that a cerclage is a life-saving procedure that is worth the risk.

Cerclage is performed using a general, spinal, or epidural anesthetic. Your doctor may give you medication to prevent infection or preterm labor, and she'll continue to check your cervix regularly for signs of further changes until the stitches come out, usually at 37 weeks. Once the cerclage is removed, labor and delivery should proceed normally, or your cerclage may also be left in place and the baby can be delivered by c-section.

Cerclage is not for everyone. Some women are ineligible for certain reasons, including:

• hyperirritability of the cervix
• the baby has already died
• her cervix is already dilated more than 4 cm
• her water has broken

Some caregivers prescribe bedrest in addition to - or instead of - cerclage. Although there's no solid evidence that staying in bed is effective, the theory is that keeping the weight of the uterus off of a weakened cervix might help.

If you've had a cerclage and experience any of the following symptoms, call your doctor immediately:

• Vaginal spotting or bleeding
• Your amniotic sac begins leaking or breaks
• You have a temperature over 100.4 degrees F (38 degrees C)
• You have signs of infection, including chills, a cough, or if you feel weak and achy.