An incompetent cervix is a weak cervix. The weakness of the cervix makes it prone to thinning and dilating before the baby is ready to be born. In a typical pregnancy, the cervix remains tightly closed until the end of pregnancy, when it will begin to thin in preparation for labor.
Having an incompetent cervix increases the risk of miscarriage in the second trimester. In fact, recurrent miscarriage after the first trimester is often the result of an incompetent cervix. The pressure of the baby as it grows causes the weak cervix to dilate before it is time. Typically, this happens early in the second trimester, as the baby grows.
According to the American College of Obstetrics and Gynecology, there are several possible causes of incompetent cervix. These include anatomical abnormalities that affect the cervix and uterus, often due to a drug used years ago to prevent miscarriage called diethylstilbestrol. Other causes include trauma to the cervix from medical procedures, such as a cone biopsy and damage to the cervix from past abortions.
Some doctors will diagnose incompetent cervix through a manual exam. However, most are now using ultrasound in making an accurate diagnosis of incompetent cervix. This test allows for a better internal picture of what is going on. Unfortunately, some women don’t have a definitive diagnosis until they have lost more than one baby.
Diagnosing incompetent cervix is difficult, since the cervix dilates without pain, in most cases. The typical treatment of stitching the cervix can’t be done if the cervix is dilated more than four centimeters. For this reason, diagnosis and treatment happens in a future pregnancy, often after one or two losses.
If a woman has a history of second trimester miscarriages due to incompetent cervix, she will be carefully monitored. Your health care provider will likely perform vaginal ultrasounds periodically. This allows the doctor to see if there are any changes to the cervix early enough to make a difference.
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