Cerclage may reduce the risk of premature labor in some twin pregnancies
January 19, 2021
The cervix is a doughnut-shaped canal that connects the uterus and vagina. As the body prepares to give birth, the cervix begins to soften and dilate to allow the baby to pass through. Sometimes, a woman’s cervix begins to open before the baby can survive outside the womb. This can lead to miscarriage or premature delivery.
We can sometimes prevent or slow this process with a cervical cerclage, a delicate procedure in which stitches are placed around the cervix, similar to a drawstring on a purse, to hold the cervix closed. The sutures are removed when a woman’s water breaks or contractions start – ideally between 36-38 weeks of pregnancy – to allow labor to proceed naturally.
For singleton pregnancies (just one baby), limited data suggests that “emergent” cerclage placement may delay delivery and therefore improve the chance of survival for the infant.
With twin pregnancies, the risks of preventive cerclage historically outweigh the potential benefits. Placing the stitch is a complex task – there is the risk of incidentally rupturing the membranes or infection, as with any procedure. Past studies found that women with twin pregnancies who received a cerclage tended to deliver earlier than those who didn’t.
However, a new study challenges this perspective. Researchers found that, in a specific subset of patients with twin pregnancies – women experiencing cervical dilation before 24 weeks of gestation – emergency cerclage placement may extend pregnancy nearly six weeks and reduce infant mortality by 77%.
While encouraging, these findings do not mean cerclage is the best choice for all, or even most, twin pregnancies. Twins born before 24 weeks have a low survival rate, and those born soon after 24 weeks face an increased risk of serious complications that may require time in the neonatal intensive care unit (NICU) or advanced cognitive or physical care as the child grows.
Whether to choose emergent cerclage, particularly in twin pregnancies, is a personal and sometimes difficult decision. For some patients, these factors are worth the risk. Others may choose to avoid the risks of cerclage and allow the natural progression of their pregnancy. Ultimately, the decision is yours. Our goal is to provide information and support you in your choices.
When cerclage may help in one-baby pregnancies
Your doctor will review your medical history, perform a physical exam, and possibly a transvaginal ultrasound to determine whether your pregnancy may benefit from a cerclage.
Preventive cerclage placement
Your provider may offer cerclage placement before early cervical dilation if you have risk factors for preterm delivery such as:
- A history of early pregnancy loss
- A short cervix (2.5 cm or less)
- Structural abnormalities of the cervix or uterus
- Cervical damage from past pregnancy trauma or gynecologic surgery
Preventive placement typically occurs at 12 to 14 weeks of pregnancy. In singleton pregnancies with prophylactic cerclage, approximately 80% to 90% of patients make it to at least 37 weeks before going into labor.
Emergency cerclage placement
Emergent cerclage placement is more complex and may be offered in a singleton pregnancy if the cervix begins to dilate before 22 weeks – the age of gestational viability, after which babies are more likely to survive if born early. In these cases, preterm birth is still highly likely.
If the membranes are in the cervix, we must attempt to tuck them back into the uterus before stitching the cervix. This step can reduce the risk of rupturing the membranes, which can lead to early labor and pregnancy loss.
Having an honest conversation with your doctor is crucial. Some patients choose to proceed with cerclage and others decide to wait and see what happens naturally. We will give you as much information as possible to help make this personal decision.
Cerclage in twin pregnancies
Twin pregnancies are generally more complex due to increased risk for complications such as preeclampsia and gestational diabetes. Preterm birth is common – about half are born before 37 weeks, and 10% before 32 weeks.
Most of the limited research available has shown that preventive cerclage is ineffective and may lead to more preterm births. But the latest twin pregnancy study suggests that in emergency situations, when the cervix is already open, cerclage placement can delay preterm birth by an average of 5.6 weeks. Most of the patients in the study who received an emergency cerclage delivered around 29 weeks, compared to 22 weeks for those who did not.
Particularly with twin pregnancies, extra gestational time can make a vast difference in fetal development. In this trial, emergency cerclage placement reduced infant mortality by 77% for patients whose babies had a better chance of surviving preterm birth.
What to expect if you get a cerclage
If you must choose between getting or not getting a cerclage, please know that there is nothing you could have done to prevent early cervical dilation. It is an unfortunate risk of pregnancy that can happen to any patient.
The procedure is typically done through the vagina under regional or general anesthesia. The doctor will place a purse-string stitch around the cervix and pull the ends together to hold the cervix firmly closed. You’ll need to stay for a few hours or overnight in the hospital to monitor for premature contractions or labor.
Spotting or mild cramping may occur in the few days afterward, and we will recommend you rest and avoid unnecessary physical activity for 48 hours or longer after the procedure. For most patients, complications with cervical cerclage are rare but can include bleeding, infection, rupture of the membranes (water breaking), premature delivery, or pregnancy loss.
Depending on your situation, the cerclage will be removed through the vagina when you are closer to your due date, scheduled induction, or cesarean section (C-section) – or when natural labor begins.
There is no one-size-fits-all solution for most pregnancy complications, particularly in twin pregnancy. If you are concerned about the risk of premature birth, talk with your doctor. We will answer your questions without judgment and give you the information you need to make this personal decision.
To visit with an Ob/Gyn, call 214-645-8300 or request an appointment online.
