What is Incompetent Cervix (IC)?

What is Incompetent Cervix (IC)?

During pregnancy, as the baby grows and gets heavier, it presses on the cervix. This pressure may cause the cervix to start to open, resulting in preterm birth and possibly the loss of the baby because of the shortened gestational length. It is estimated that incompetent cervix happens in 1 out of 100 pregnancies and is the cause of 25% of all second trimester losses.

Incompetent cervix usually occurs during the second trimester, but it can occur as late as the early third trimester. With incompetent cervix, the cervix usually opens without labor or contractions. However, once the cervix has opened partially, sometimes contractions may begin. Diagnosis can be made either manually or with a vaginal ultrasound. The use of ultrasound technology has been very helpful with diagnosis, which is made when the cervical os (opening) is greater than 2.5 cm, or the length has shortened to less than 20 mm. Any shortening of the cervix should be carefully monitored. Here is a list of factors that can contribute or cause cervical incompetence…

• DES exposure
• Cervical trauma such as a D&C (dilation and curettage) from a termination or a miscarriage
• Previous surgery on the cervix, including biopsies
• Damage during a difficult birth
• Hormonal influences
• Congenitally short cervix
• Malformed cervix or uterus from a birth defect
• Uterine anomalies

How is IC Diagnosed?

Incompetent cervix is not routinely checked for during pregnancy. Because of this, it is not usually diagnosed until after one or more second or third trimester losses have occurred. Generally, these early miscarriages have minimal contractions or bleeding and the birthing process is completed rapidly. Women can be evaluated before and during pregnancy by ultrasound. If you have any of the factors that can potentially cause incompetent cervix you should have regular pelvic ultrasounds. The ultrasound can be used to measure the cervical opening or the length of the cervix. A manual pelvic exam can not detect funneling. Funneling is where the internal portion of the cervix, internal os (portion of the cervix closer to the baby) has begun to efface. The external os will be unaffected if diagnosed in time. In other words, the cervix is starting to open inside, but has not begun to open outside.

What is the treatment for IC?
If you are diagnosed after a second trimester loss or prior to pregnancy and it is suspected that you will have problems with the strength of your cervix, a preventative cerclage can be performed between weeks 12 and 16. It is said that the earlier you have the cerclage performed the more likely the pregnancy is to continue.

Sometimes a physician discovers a partially dilated and shortened cervix during a routine pelvic examination during the mid-trimester of pregnancy. If you are diagnosed with incompetent cervix during pregnancy, a rescue (or emergency) cerclage can be performed. For diagnosis made during pregnancy, you must meet certain criteria before a cerclage can be performed. You should be on bedrest following a rescue cerclage. You are not eligible for the cerclage if you have:

• Increased irritability of the cervix
• Your baby has already died
• You are more than 4 cm dilated
• Your membranes have ruptured

What is a cerclage?

A cerclage is a suture used to sew the cervix closed to reinforce a weak cervix. It is usually done between weeks 12 and 16. A cerclage will usually be removed between weeks 36 and 38 to prevent problems during labor and delivery. There are three different types of cerclage. They are the McDonald, the Shirodkar, and the Trans Abdominal (the Trans Abdominal cerclage can be done in a few different ways and may also be called the Hefner - or Wurm - procedure, the Uterosacral cardinal ligament, or the Lash). The McDonald and the Shirodkar are the most commonly used methods.

The McDonald cerclage is the most common, and the easiest to perform. It is done with a 5 mm band of suture placed on the cervix when there is effacement of the cervix or a history of prior incompetent cervix. It is usually removed at 37 weeks in an uneventful pregnancy (Certain problems, like infection, preterm labor or premature rupture of the membranes, make earlier removal more likely).

The Shirodkar cerclage is usually placed higher on the cervix than the McDonald cerclage. It is often used when a previous McDonald cerclage has failed or when the cervix is more likely to open up after suture. The cerclage is usually placed entirely under the skin, and because it was left in place, it originally required a cesarean delivery. Today, most physicians perform a modified Shirodkar, in which the stitch can be removed and a vaginal delivery can occur. Ask your practitioner which procedure they perform.

A Trans Abdominal cerclage is used when the cervix has been extensively biopsied, damaged, or removed. It is also used in cases of higher-multiple pregnancies. The suture is inserted through the abdomen above the pubic area. It is usually placed between weeks 11 and 12. Barring complications, the cerclage will then be removed at 37 weeks. If problems arise, the cerclage can usually be removed through the vagina. When the pregnancy continues to full-term, a cesarean section is performed and the suture left in place to protect future pregnancies. After two pregnancies, the cerclage may have to be replaced.

Are there any risks to having a cerclage?

The risks of having a cerclage are minimal. Most physicians feels that a cerclage is a lifesaving procedure that is worth the possible risks involved. The risks are…

• Premature rupture of membranes (1-9%)
• Chorioamnionitis (Infection of the amniotic sac, 1-7%) (This risk increases with gestational age at onset of IC and is at 30% for a cervix that is dilated more than 3 cms.) This risk can be minimized by taking antibiotics following the procedure
• Preterm labor and premature rupture of the membranes
• Cervical laceration or amputation (This can be at the procedure or at the delivery, from scar tissue that forms on the cervix.)
• Bladder injury (rare)
• Maternal hemorrhage
• Cervical dystocia
• Uterine rupture