Cervical insufficiency, or an incompetent cervix, is a relatively rare, but potentially serious complication of pregnancy. A cervix is termed “incompetent” when it cannot take the weight pressing against it as the fetus grows. This weakening may cause the cervix to open long before the baby is ready to be born. Although it is fortunately an uncommon occurrence, appearing in approximately one of every one hundred pregnancies, it is important to know the causes, symptoms, and treatments of this condition. Untreated, an incompetent cervix can lead to miscarriage or premature labor, and is one of the leading causes of miscarriage during the second trimester.
The causes of cervical insufficiency are not always diagnosed, but there are a few factors that have been determined to increase the risk of an incompetent cervix. These can include damage done to the cervix by previous labor difficulties or certain cervical procedures. A standard cervical biopsy, such as that performed at a woman’s annual exam does not cause insufficiency, but laser ablation to remove abnormal cervical cells may. Uterine malformations, a birth defect of the uterus, can also cause incompetent cervix. This means that women whose mothers took Diethylstilbestrol (DES) while pregnant with them are at an increased risk as well. DES is a drug prescribed in the 1960s and 1970s to reduce the risk of miscarriage that has since been determined to increase these defects of the uterus. Previous miscarriages, or a dilation and curettage (D&C) after miscarriage, are also factors which can contribute to an incompetent cervix.
Signs and Symptoms
Unfortunately, many cases of cervical insufficiency remain asymptomatic. Once it is known that a cervix is weakened, preventative measures can be taken in subsequent pregnancies, but often this diagnoses does not occur until after miscarriage or premature labor has occurred in the first pregnancy. In these cases, the cervix will dilate without the woman feeling the usual contractions. She may notice some bleeding or spotting, but by this time labor is often imminent. Signs that can occur in time for treatment are increased discharge or a heavy feeling in the pelvic or rectal areas.
If cervical insufficiency is diagnosed, immediate medical care is necessary. The usual treatment for this condition is cerclage, a suturing of the cervix to keep it from continuing to dilate prematurely. This is done at the beginning of the second trimester, or as early as the problem is discovered, to increase its success rate. Emergency cerclages can be performed into the third trimester.
There are five types of stitches used with a cerclage, each with its own strengths and weaknesses. The McDonald stitch is used when possible because it is temporary and still allows for a vaginal birth. The Shirodkar stitch follows, as it may be temporary depending on how it must be tied. The abdominal and Hefner stitches are used when the cervix is exceptionally short, or the cervical insufficiency is not determined until late in pregnancy. The Hefner stitch can be taken out before delivery, but the abdominal stitch cannot. The final cerclage type is the Lash stitch, which is only used in cases of severe cervical trauma or defect before the woman is pregnant. Due to the extreme nature of the Lash cerclage, this stitch lasts for life, and cesarean birth is the only option available.
While cerclage of all types is considered relatively safe for mother and baby, there are some complications which can occur. These include early rupture of membranes (premature water breaking), infection of the amniotic sac, uterine or bladder injury, excessive cervical scar tissue, hemorrhage, and preterm labor. These are rare, however, and the majority of cervical sutures are not only free of complications, but successful in aiding the woman to carry her baby to term.
Often the patient may return home a few hours after the cerclage procedure, but she may be kept overnight to monitor for signs of premature labor, depending on the degree of her previous dilation. A doctor will advise bed rest for two to three days after the sutures are placed, and will discuss when normal physical activities may be resumed. Abstaining from sexual intercourse for at least a week will be recommended, up to the duration of the pregnancy depending on the severity of the cervical insufficiency. It is very important during this time that the woman notify her doctor if she feels lower back pain and cramping or contractions, fever, bleeding, nausea, vomiting, water leakage, or other abnormal discharge. These could be signs of a failing or infected cerclage.
Not all women will be eligible to receive a cerclage. If her water has already broken, cerclage cannot stop labor. Stitches are also impossible if the cervix has already dilated beyond four centimeters, or it is especially irritated. In these cases, bed rest in the Trendelenburg position will be prescribed. In this position, one lies at an inverted slope with the feet above the head. This helps to keep the weight of the fetus off of the incompetent cervix.
Once a woman is diagnosed with cervical insufficiency, she will need to take precautions and be treated for this condition in all future pregnancies as well. She will receive extra prenatal visits and an early cerclage before cervical dilation has progressed. An incompetent cervix will not correct itself over time, but effects are usually minimal when the woman knows about the condition prior to a pregnancy.