A cerclage is a stitch sewn around the cervix during pregnancy to keep it closed and prevent preterm birth or miscarriage. It’s used when the cervix begins to open too early, a condition called cervical insufficiency. The procedure is one of the most effective interventions for women at risk of losing a pregnancy in the second trimester, and it’s typically placed between 12 and 24 weeks of gestation.
Why a Cerclage Is Needed
The cervix is the narrow lower portion of the uterus that opens into the vaginal canal. During a healthy pregnancy, it stays firm and closed until late in the third trimester, when it gradually softens and dilates in preparation for labor. In some women, the cervix weakens and begins to shorten or open months too early, without any contractions or other signs of labor. This painless opening is what doctors call cervical insufficiency.
Without treatment, cervical insufficiency can lead to second-trimester pregnancy loss or very early preterm birth. The condition is often identified through ultrasound measurements of cervical length. A cervix that shortens to around 25 millimeters or less before 24 weeks raises a red flag, especially in women who have lost a previous pregnancy in the second trimester. A cerclage reinforces the cervix mechanically, acting like a drawstring to hold it shut until the baby is mature enough to be born safely.
Three Types of Cerclage
McDonald Cerclage
This is the most common technique. A suture is looped around the outside of the cervix in a purse-string pattern and tied at the front. It requires no cutting into the surrounding tissue, making it simpler to place and easier to remove later. Most elective cerclages use this method.
Shirodkar Cerclage
The Shirodkar technique places the stitch higher on the cervix, closer to where the cervix meets the uterus. The surgeon makes a small incision in the vaginal lining, pushes the bladder upward, and threads the suture beneath the tissue so it sits at a higher, more structurally secure position. The knot can be buried under the vaginal lining, though modern modifications often leave it accessible for easier removal. This approach is sometimes chosen when a McDonald cerclage has failed in a prior pregnancy or when the anatomy calls for higher placement.
Transabdominal Cerclage
A transabdominal cerclage (TAC) is reserved for women who can’t have a vaginal cerclage. This includes women with a very short cervix after previous surgery, an anatomically altered cervix, or a history of failed vaginal cerclage. The stitch is placed through the abdomen, either through a traditional incision or laparoscopically, and it sits right at the junction of the cervix and uterus. Because of its location, it provides the strongest mechanical support, but it comes with a significant trade-off: it requires a cesarean delivery, and removing the stitch later means another abdominal procedure. Some women choose to leave the stitch in place permanently if they plan future pregnancies.
When Cerclage Is Placed
Cerclages fall into three timing categories depending on the clinical situation. A history-indicated cerclage is placed around 12 to 14 weeks in women who have lost a prior pregnancy to cervical insufficiency. An ultrasound-indicated cerclage is placed when routine monitoring reveals a shortening cervix, usually between 16 and 24 weeks. Both of these are planned procedures.
An emergency (or “rescue”) cerclage is a different situation entirely. It’s performed when the cervix has already begun to dilate and the amniotic membranes are bulging through the opening. Emergency cerclage can be attempted between 16 and about 28 weeks of gestation, as long as there’s no active infection, bleeding, or contractions. One study of emergency cerclages placed between 24 and 28 weeks found that nearly 85% of women gained at least 60 additional days of pregnancy, compared to about 56% of women managed with bed rest alone. The rate of serious newborn complications was also significantly lower in the cerclage group.
What the Procedure Feels Like
A vaginal cerclage is a short procedure, typically taking 30 to 60 minutes. It’s performed under spinal or general anesthesia, so you won’t feel pain during the surgery itself. Afterward, you can expect some cramping, light spotting, and discomfort for a few days. Most women are discharged the same day or the following morning.
Recovery instructions are straightforward. Plan to rest for two to three days after the procedure. For the first one to two weeks, you’ll need to avoid sexual intercourse, strenuous exercise, heavy lifting, and swimming. Your doctor will likely schedule a follow-up ultrasound within one to two weeks to confirm the stitch is in place and the cervix is stable. After the initial healing period, most women return to normal daily activities, though your provider may recommend ongoing restrictions on vigorous exercise depending on your specific risk level.
Risks and Complications
Cerclage is generally safe, but it does carry real risks. The most significant is infection of the amniotic fluid and membranes, known as chorioamnionitis. Timing matters: when cerclage is delayed until later in the second trimester (past 18 weeks), the risk of this type of infection increases roughly 2.5 times, and the chance of the membranes rupturing before 32 weeks triples. When the infection takes hold, it tends to involve multiple types of bacteria, which can complicate treatment.
Other possible complications include:
- Premature rupture of membranes, where the water breaks too early, sometimes triggered by the procedure itself
- Cervical tearing, if the cervix dilates forcefully against the stitch during contractions
- Bleeding at the time of placement or removal
- Preterm labor that the cerclage cannot prevent
The risk of complications is lowest when cerclage is placed early and electively, before the cervix has begun to change. Emergency cerclages carry higher complication rates because the cervix is already compromised.
How Well Cerclage Works
Success depends heavily on the timing and the reason for placement. History-indicated cerclages placed early in pregnancy for women with a clear pattern of cervical insufficiency have the best outcomes. Emergency cerclages are riskier, but still offer a meaningful advantage over no intervention. In one study of emergency cases, the rate of perinatal loss was under 3%, and more than 9 out of 10 pregnancies continued long enough for the baby to survive.
Cerclage works best as part of a broader monitoring plan that includes regular cervical length checks by ultrasound and, in many cases, progesterone supplementation. It’s not a guarantee against preterm birth, but for the specific problem of a weak cervix, it remains the most direct and effective fix available.
Removal and Delivery
A vaginal cerclage (McDonald or Shirodkar) is typically removed around 36 to 37 weeks of pregnancy. By that point, the baby is considered early term and the cervix needs to be free to dilate for labor. Removal is a quick office or bedside procedure that usually doesn’t require anesthesia. Most women describe brief discomfort similar to a cervical exam. Labor can begin within hours to days after removal, though some women carry for another week or more.
If preterm labor or premature rupture of membranes occurs before the scheduled removal, the cerclage is taken out at that time to prevent cervical damage. For transabdominal cerclages, a cesarean section is planned, and the stitch may be left in place for future pregnancies or removed during the same surgery.