What is an incompetent cervix, how does it cause miscarriage or pre-term birth, and what are the treatments to improve outcomes?
An incompetent cervix, also known as cervical insufficiency, means the cervix dilates too early, resulting in premature birth or pregnancy loss. Cervical incompetence happens in about 1% of all pregnancies, and it is most common in the middle of the second or third trimester. If you’ve experienced cervical insufficiency in the past, there are treatment options.
We asked Ted Anderson, M.D., Ph.D., of Vanderbilt Center for Women’s Health, to explain more about the incompetent cervix and what can be done to help.
Typically during labor, the cervix dilates in response to uterine contractions and the pressure of the baby’s head on the cervix. That process then leads to birth. “An incompetent cervix,” Anderson said, “is when the cervix begins to dilate through no pressure or stimulus from the uterus at all. It can’t stay shut. It just relaxes and begins to open.”
Without any intervention, an incompetent cervix can lead to premature birth or a miscarriage. However, sometimes intervention can help. Plus, treatment can be done prior to pregnancy for individuals who have a history of incompetent cervix.
Intervention during pregnancy
“When this happens for the first time to a pregnant woman,” Anderson said, “it often comes as a surprise to both the woman and the physician. There’s not a great way to predict this.” Incompetent cervix may occur as a result of prior surgery on the cervix, an anatomic abnormality of the uterus or cervix, or certain connective tissue disorders. One of the greatest risk factors for incompetent cervix is having had an incompetent cervix with a previous pregnancy.
Sometimes the pregnancy can be completed with the help of a technique called rescue cerclage. “If the cervix is already beginning to dilate,” Anderson explained, “we may put a stitch at the end of the cervix where it extends into the vagina in order to hold it closed long enough for the baby to mature.”
However, this technique doesn’t always work, simply because the material, which is a thick suture, may not be enough to stop the cervix from opening.
Intervention before pregnancy
If you have experienced incompetent cervix previously, you’re at risk for it happening again. In this case, your doctor might recommend an abdominal cerclage in preparation for carrying a baby.
“Instead of putting that stitch around the end of the cervix,” Anderson said, “we put a stitch around the top of the cervix inside the pelvis where it meets the uterus.” This procedure uses a 5-millimeter cloth band rather than a suture. “So it’s a big band, at a better place in the cervix,” he added. “And that really is very effective at preventing the cervix from dilating.”
Historically, the abdominal cerclage required an incision similar to a C-section and a stay in the hospital, but now the surgery is performed with a minimally invasive approach. “What we’re doing now is we’re able to place these laparoscopically,” Anderson said. “What that means is the patient has a quick outpatient procedure with tiny little incisions, about half an inch.”
If you do have an abdominal cerclage prior to pregnancy, you will need to have a C-section rather than a vaginal birth. “The downside is that we’re so effective in preventing the cervix from dilating,” Anderson explained, “it will also not dilate at the end of a normal pregnancy.”
You will not need to have the cerclage removed after giving birth, and it remains in place in the event of a future pregnancy. “You have normal cervical function, you have normal ability to get pregnant, and normal menstruation,” Anderson said. “The abdominal cerclage doesn’t affect any function of reproduction or the reproductive tract at all.” However, with any additional pregnancies, you will continue to give birth by C-section.
“We’ve actually had very good success,” Anderson added regarding the procedure. “And it gives me a great sense of satisfaction and a feeling of making a great contribution to address a very serious problem that has a tremendous impact.”