American College of Obstetrics and Gynecology's ("ACOG") defines an incompetent cervix as a "painless dilation and delivery in the second trimester" of pregnancy.
This term is used interchangeably with cervical insufficiency. The problem is weak cervical tissue causes or leads to premature birth or the loss of a pregnancy. It does not get better with time. The cervix is the lower part of the uterus that sits at the top of the vagina. It functions as the opening of the uterus into the birth canal during labor and birth.
Before pregnancy, the cervix is normally closed and firm. Throughout the pregnancy as the women's body prepares for childbirth, the cervix will slowly soften and gradually dilate to allow for the passage of the baby. When the baby is ready to come out of the uterus, the hormones are released that start signaling the body and trigger pain and contractions. Contractions occur when muscles of the uterus get tight and then relax to help push the baby out of the uterus during labor and birth.
However, if you have an incompetent cervix, the cervix might begin to open too soon. The cervix is struggling to hold the pregnancy normally. So the mere weight of the pregnancy can open the cervix without labor. This can cause a premature birth or a miscarriage. Cervical incompetence occurs in about 1 out of 100 pregnancies. About 25% of miscarriages in the second trimester are due to incompetent cervix.
For many women, the symptoms do not show during their early pregnancy. The most accurate sign of incompetent cervix is a painless cervical dilation and bulging fetal membranes during the second trimester of pregnancy. However, expecting mothers will often not be able to feel this at all and only healthcare providers will be able to notice this with an ultrasound during prenatal care. Some women experience mild discomfort or spotting over the course of several days or weeks starting between 14 and 20 weeks of pregnancy. Some other symptoms may include:
- Pelvic pressure
- A new or different backache
- Abdominal cramps
- Change in vaginal discharge (likely clear and odorless)
- Light vaginal bleeding
The is no definitive test for cervical incompetency. It is a clinical diagnosis based pattern of facts. Generally, incompetent cervix is not routinely checked for and is not diagnosed until after the second or third trimester, usually after a miscarriage has occurred. Women can be evaluated and tested before pregnancy or in early pregnancy.
Physicians will use an ultrasound to check for any potential indicators for cervical incompetency. The key is the length of the cervix. A vaginal probe ultrasound will show very clear landmarks for the internal loss, the external loss and the length of the canal connecting the two. Serial testing is helpful because you want to see if there are changes over time. If the cervix is monitored throughout the pregnancy and stays at a same length, they is clearly leas risk that she has an incompetent cervix.
The exact reason why cervical incompetency occurs in certain pregnancies is not known. However, there are a number of specific risk factors for incompetent cervical including:
- Cervical trauma - some surgical procedures that are used to treat cervical abnormalities related to abnormal PAP smear can cause cervical insufficiency. Other procedures such as dilation and curettage (D&C) procedures could be associated with cervical insufficiency.
- Congenital conditions - uterine abnormalities and genetic disorders that affect the body's connective tissues might cause an incompetent cervix. Additionally, exposure to synthetic forms of estrogen before birth has been linked to cervical insufficiency.
An incompetent cervix may pose grave risk for your pregnancy, especially during the second trimester. The most serious consequences of cervical insufficiency are premature birth and sudden pregnancy loss. If cervical incompetency is diagnosed or suspected early one, doctors will closely monitor the fetus and cervix to prevent premature birth and miscarriage. Premature birth can lead to a host of potential neonatal risks and birth injuries including infant brain damage.
Doctors may recommend different treatment options for an incompetent cervix based on the term of the pregnancy and a women's prior medical history. The following are some common treatments for an incompetent cervix:
- Repeated ultrasounds - if you have a history of premature birth or history that may increase the risk of cervical insufficiency, your doctor may monitor the cervix and fetus very closely. This will allow the doctor to take precautions and be prepared for cervix dilation.
- Progesterone supplementation - if you have a prior medical history of premature birth, your doctor may recommend weekly shots of hydroxyprogesterone corporate, a synthetic form of the hormone progesterone. This will be most likely be given the second and third trimester. This is used to help lower the risk of giving birth too soon. However, the use of progesterone in cervical insufficiency is still somewhat controversial.
- Cervical cerclage - In some cases doctors may recommend cervical cerclage. This is surgical procedure where the cervix is stitched closed with strong sutures. The stitch ties an incompetent/insufficient cervix, to keep the cervix closed, prevents the cervix from opening, and prevents prolapse of the membranes or rupture of the membranes. This procedure is performed between week 14-16 of pregnancy and the sutures get removed between 36-38 weeks to prevent any problems during labor. Removing the cerclage does not result in spontaneous delivery of the baby. This comes with some risks, however. Some possible complications of cervical cerclage include uterine rupture, maternal hemorrhage, infertility, bladder rupture, cervical laceration, preterm labor and premature rupture of the membranes. There is also a high risk of damage to the cervix for future pregnancies. Even with the risk of possible complications, many healthcare providers will suggest this procedure if there is a high suspicion that a patient has incompetent cervix
The standard of care requires the obstetrician treating a patient with suspicion of an incompetent cervix to closely monitor the patient for cervical incompetence by performing ultra sonographic examinations to determine cervical changes and complete vaginal examinations. This must begin after the first trimester. If the patient has signs and symptoms of cervical insufficiency such as softening, shortening, thinning effacement, or early dilatation of the cervix or funneling of membranes, then the OB must put a stitch in the cervix (cerclage) and restrict the patient's physical activities.
There is no specific method to effectively prevent incompetent cervix. However, there are different ways to promote a healthy, full term pregnancy. This can decrease - but clearly not eliminate - the consequences of an incompetent cervix. These methods help keep a healthy pregnancy:
- Receiving regular prenatal care
- Eating a healthy diet
- Gaining the right amount of weight
- Avoiding risky substances such as alcohol and smoke