What Is Cervical Insufficiency? Types of Cervical and Abdominal Cerclage

Cervical insufficiency, or cervical incompetence, is the early shortening and opening of the cervix without significant pain or regular labor contractions, because the cervix cannot provide the structural and functional support needed to carry the pregnancy.

Especially in the second trimester of pregnancy, this condition can lead to late pregnancy loss, premature rupture of the membranes or preterm birth. Cervical insufficiency does not always cause symptoms. In high-risk pregnancies, monitoring cervical length with transvaginal ultrasound and, when needed, using vaginal progesterone or cervical cerclage can help carry the pregnancy to later weeks.

What is the role of the cervix in pregnancy?

The cervix, also known as the neck of the womb, is the lower part of the uterus that opens into the vagina. In a healthy pregnancy it stays closed and long enough, helping the baby develop inside the uterus.

As labor approaches, the cervix begins to soften, shorten and open. In cervical insufficiency, these changes occur before it is time to give birth, most often in the second trimester of pregnancy (well before term).

Cervical insufficiency should not be viewed as “a weak cervix” alone. The anatomy of the cervix, cervical length, the course of previous pregnancies, infection and other biological processes that can trigger preterm labor may all play a role together.

What are the symptoms of cervical insufficiency?

Cervical insufficiency can sometimes progress without any symptoms. In some mothers-to-be, the following symptoms may occur:

• A feeling of pressure or pushing down in the pelvic area
• Lower back pain
• Mild abdominal or groin cramps
• Increased vaginal discharge or a change in its consistency
• Light vaginal bleeding or spotting
• A feeling of fullness in the vagina
• Leakage of fluid

Having these symptoms does not necessarily mean cervical insufficiency. However, it is important for mothers-to-be who have previously had a second-trimester pregnancy loss or preterm birth to be assessed without delay.

Important: If you have severe or regular pain, vaginal bleeding, leakage of fluid, fever or foul-smelling discharge, seek medical care urgently.

What causes cervical insufficiency?

The exact cause of cervical insufficiency cannot be identified in every patient. The main conditions that may increase the risk are:

• A second-trimester pregnancy loss with painless opening of the cervix
• A history of previous spontaneous preterm birth
• Cervical cerclage in a previous pregnancy
• Conization or similar surgical procedures on the cervix
• Previous trauma to the cervix
• Congenital structural differences of the uterus or cervix
• A markedly short cervix
• Certain surgical operations affecting the cervix

Having one of these risk factors does not necessarily mean that cervical insufficiency will develop. The diagnosis and follow-up plan is prepared by evaluating pregnancy history, ultrasound and examination findings together.

Can cervical insufficiency be detected during pregnancy?

Yes, cervical insufficiency can be detected during pregnancy. However, in some patients the first sign may be painless opening of the cervix, leakage of fluid or a second-trimester pregnancy loss.

Three main assessments are used for diagnosis:

Previous pregnancy history

Opening of the cervix without significant pain or contractions in previous pregnancies, a second-trimester loss, premature rupture of the membranes or a very early preterm birth may suggest cervical insufficiency.

Transvaginal ultrasound

The most reliable method for assessing cervical length is transvaginal ultrasound. In high-risk patients, cervical length is usually measured serially between weeks 16 and 24 of pregnancy.

During the ultrasound, besides the length of the cervix, the doctor also checks for opening of its inner part, or “funneling” as it is called.

Physical examination

In some patients, a speculum or vaginal examination may show that the cervix has opened painlessly and that the amniotic sac is bulging into the cervical canal.

In such a case, after assessing for infection, labor, bleeding and the state of the amniotic sac, an emergency cerclage may be considered.

What should the cervical length be in millimeters?

Cervical length is evaluated according to the week of pregnancy, the patient’s history and whether the pregnancy is singleton or multiple. Measurements that guide treatment must be taken with a standard method using transvaginal ultrasound.

In a patient with a singleton pregnancy and no history of spontaneous preterm birth, a mid-pregnancy cervical length of 25 mm or less is considered a short cervix, by definition.

However, the 25 mm threshold does not mean that every patient will automatically receive a cerclage.

Below what cervical length is cerclage needed?

The decision for cerclage is not made just by looking at how many millimeters the cervix measures. The patient’s previous pregnancy history, the current week of pregnancy, whether the cervix has opened and any signs of infection are all evaluated together.

If there is no history of preterm birth or cervical insufficiency

In a singleton pregnancy and before 24 weeks:

• If the cervix is 21–25 mm: Vaginal progesterone may be considered through a shared decision with the patient.
• If the cervix is 20 mm or less: Vaginal progesterone is recommended.
• If the cervix is 10–25 mm with no opening: Routine cerclage is not recommended.
• If the cervix has progressively shortened to below 10 mm: Cerclage may be considered on an individual basis, especially if shortening continues despite progesterone. Even in this case, cerclage is not an automatic requirement.
• If the cervix is open on physical examination: Emergency cerclage may be considered regardless of cervical length.

SMFM does not recommend routine cerclage for a short cervix of 10–25 mm in patients without a history of preterm birth and without cervical opening. For patients with a cervix of 20 mm or less, the first-line approach is vaginal progesterone. SMFM short cervix guideline

ISUOG states that cerclage may be considered in selected patients whose cervix progressively shortens to below 10 mm despite progesterone. ISUOG guideline on preterm birth and the cervix

If there is a previous preterm birth or second-trimester loss

In a singleton pregnancy with a previous spontaneous preterm birth or a second-trimester loss consistent with cervical insufficiency, if the cervical length before 24 weeks measures 25 mm or less then ultrasound-indicated cerclage may be considered.

General approach based on cervical measurement

Can cervical insufficiency be prevented?

It is not possible to prevent every case of cervical insufficiency. However, by identifying high-risk patients before pregnancy or in early pregnancy, the risk of late pregnancy loss and preterm birth can be reduced.

A preventive approach may include:

• Detailed evaluation of previous pregnancy losses
• An obstetrics and gynecology examination before pregnancy
• Transvaginal cervical monitoring between weeks 16 and 24 in high-risk patients
• Vaginal progesterone in suitable patients
• Cerclage based on history, ultrasound or examination findings
• Avoiding multiple pregnancy in IVF treatment
• Early evaluation of signs of infection

To prevent cervical insufficiency, routine and prolonged bed rest is not recommended. Staying immobile can create additional risks such as blood clots, muscle loss and bone weakening.

Is double embryo transfer appropriate in IVF treatment?

In patients with a history of cervical insufficiency, second-trimester pregnancy loss or very early preterm birth, avoiding multiple pregnancy is important.

A twin pregnancy can stretch the uterus more and increase the risk of preterm birth. Placing a cerclage later in a twin pregnancy does not fully eliminate this risk either.

Therefore, in IVF patients with cervical insufficiency or a serious history of preterm birth, elective single embryo transfer should be strongly preferred.

Defining double embryo transfer for every patient as an “absolute contraindication” is not correct. Nevertheless, in patients for whom multiple pregnancy could increase serious health risks, it is a safer approach not to transfer more than one embryo and to prioritize single embryo transfer.

ASRM recommends not transferring more than one embryo in patients for whom multiple pregnancy could pose a significant health risk. Single embryo transfer is the most direct way to reduce multiple pregnancies in assisted reproduction. ASRM embryo transfer recommendations

Is cerclage performed in twin pregnancies?

In twin pregnancies, based solely on the finding of a short cervix, routine cerclage is not recommended. In twin pregnancies, the causes of cervical shortening and the response to treatment may differ from those in singleton pregnancies.

SMFM does not recommend the routine use of cerclage, progesterone or a cervical pessary for cervical shortening in twin pregnancies outside of clinical trials. However, in special situations where marked cervical opening is found on physical examination, the decision can be individualized with a perinatology evaluation.

Therefore, in IVF treatment, rather than trying to secure a twin pregnancy later with a cerclage, whenever possible a singleton pregnancy should be the goal.

What is cervical cerclage?

Cervical cerclage, is the placement of a strong stitch around the cervix to prevent or delay its early opening. It is also commonly known as “a stitch in the cervix” among patients.

The aim of cerclage is not to prevent all preterm births with certainty. When performed in the right patient at the right time, it can help the pregnancy reach later weeks by reducing the risk of late pregnancy loss and preterm birth.

Types of cerclage by indication

Cerclage is divided into three main groups according to its indication.

History-indicated cerclage

History-indicated cerclage is planned based on what happened in the patient’s previous pregnancies.

It may be considered especially in the following situations:

• A second-trimester loss with painless opening of the cervix
• Recurrent late pregnancy losses
• Cerclage in a previous pregnancy due to cervical insufficiency

The procedure is usually planned around weeks 12–14 of pregnancy. The exact timing is determined by the patient’s history and the status of the current pregnancy.

Ultrasound-indicated cerclage

This is a cerclage performed when serial transvaginal ultrasound scans show marked shortening of the cervix.

It may be considered especially in patients with a previous spontaneous preterm birth or second-trimester loss whose cervical length in the current singleton pregnancy before 24 weeks measures 25 mm or less on ultrasound.

Seeing a short cervix on ultrasound does not mean that every patient will automatically receive a cerclage.

Physical examination-indicated emergency cerclage

This is a cerclage considered when the cervix is found to have opened painlessly in the second trimester of pregnancy. It is also known as an “emergency cerclage” or “rescue cerclage” in clinical practice.

In some patients, the amniotic sac may have bulged toward the cervix or into the vagina. Emergency cerclage carries a higher risk of infection and rupture of the membranes than a planned cerclage.

Before the procedure, active infection, bleeding, uterine contractions and the state of the amniotic sac are carefully assessed.

Types of cerclage by surgical approach

Cerclage is divided into two main groups according to the route by which the stitch is placed:

• Transvaginal cerclage
• Transabdominal cerclage

What is transvaginal cerclage?

Transvaginal cerclage is the placement of the stitch around the cervix through the vagina. It is the first-choice method for most patients.

Its main advantages are a lower surgical burden than abdominal cerclage, easy removal of the stitch and, in suitable patients, the possibility of a vaginal birth.

The most commonly used methods for transvaginal cerclage are the McDonald and Shirodkar techniques.

McDonald cerclage

In McDonald cerclage, a purse-string-like stitch is placed around the cervix. Because it is technically simpler and the stitch is easy to remove, it is one of the most commonly used methods.

Shirodkar cerclage

In Shirodkar cerclage, the stitch is placed higher up on the cervix. In some cases, the bladder may need to be separated from the cervix. For this reason, it can be technically more extensive than the McDonald method.

Which technique is used depends on the anatomy of the cervix, previous surgeries and the doctor’s assessment. No single method can be said to be superior to the other in all patients.

What is abdominal cerclage?

Abdominal cerclage, is the placement of the stitch at the upper part of the cervix through the abdomen, using open surgery or laparoscopy.

Because its surgical burden is greater than that of transvaginal cerclage, it is not routinely the first option.

Who can have an abdominal cerclage?

Abdominal cerclage may be considered in the following situations:

• A very early preterm birth or pregnancy loss despite a properly performed vaginal cerclage
• A cervix that is markedly shortened due to previous surgeries
• Placing a cerclage through the vagina being anatomically impossible
• Previous surgery affecting the cervix, such as trachelectomy
• Failure of a previous vaginal cerclage

SMFM recommends that patients whose subsequent singleton pregnancy, despite a previous vaginal cerclage, ended in spontaneous birth before 28 weeks be offered the option of transabdominal cerclage. SMFM transabdominal cerclage guideline

When is abdominal cerclage performed?

Abdominal cerclage is preferably performed before pregnancy or in the first trimester of pregnancy. Depending on the patient’s situation, laparoscopic or open surgery may be preferred.

The stitch is usually not removed and can be left in place for future pregnancies. However, because the stitch sits in the upper part of the birth canal, birth must be by caesarean section.

Vaginal or abdominal cerclage?

For most patients, the first option is transvaginal cerclage. Abdominal cerclage should not be thought of as a better or stronger method for everyone.

When choosing the method, the week and manner in which the previous pregnancy ended, whether a cerclage was performed before, the anatomy of the cervix and previous surgeries are evaluated together.

Up to which week of pregnancy can cerclage be performed?

The timing of cerclage depends on the reason it is performed.

• History-indicated planned cerclage: Usually performed at weeks 12–14.
• Ultrasound-indicated cerclage: Usually performed before 24 weeks of pregnancy.
• Physical examination-indicated emergency cerclage: The evidence is strongest before 24 weeks.
• Abdominal cerclage: Preferably performed before pregnancy or in the first trimester.

ACOG states that emergency cerclage may be considered before 24 weeks, provided there is no labor, rupture of the membranes or intrauterine infection. ACOG guidance on periviable birth

According to RCOG, vaginal cerclage is usually performed between weeks 12 and 24 of pregnancy. Although it may be considered at later weeks in some highly selected patients, the scientific evidence for this period is more limited. RCOG patient information on cervical stitch

Why is infection important in cervical insufficiency?

The cervix and the cervical mucus plug act as a natural barrier that prevents microorganisms in the vagina from moving up into the uterus.

Shortening or opening of the cervix can impair this barrier and make it easier for microorganisms to move up into the uterus.

There may be a two-way relationship between infection and cervical insufficiency:

• Opening of the cervix can increase the risk of ascending infection.
• Intrauterine infection and inflammation can cause the cervix to shorten.
• Infection can weaken the fetal membranes and lead to premature rupture of the membranes.
• The risk of chorioamnionitis, maternal infection, fetal infection and preterm birth may increase.
• Placing a cerclage in the presence of active infection can cause the infection to spread within the uterus.

RCOG states that cerclage does not only provide mechanical support to the cervix; it may also help preserve the barrier that cervical length and the mucus plug form against ascending infection. RCOG Cervical Cerclage Guideline

How is infection assessed before cerclage?

Especially in patients for whom emergency cerclage is being considered, the possibility of infection is carefully investigated. The assessment may include:

• Asking about fever, abdominal pain and foul-smelling discharge
• Measuring the mother’s temperature and pulse
• Speculum examination
• Blood tests
• Testing vaginal or cervical samples when needed
• Amniocentesis in selected emergency cases

A single blood test or vaginal culture cannot always definitively rule out intrauterine infection. The findings must be evaluated together.

Cerclage is usually not recommended in the presence of active infection, regular uterine contractions, significant bleeding or ruptured membranes.

How is cerclage surgery performed?

Transvaginal cerclage is usually performed in an operating room under spinal or general anesthesia. The cervix is reached through the vagina and a stitch is placed around it.

The procedure usually takes less than an hour. Depending on the patient’s clinical condition, discharge on the same day or the next day may be possible.

Abdominal cerclage, on the other hand, is performed under general anesthesia with laparoscopic or open surgery. Recovery may take longer than with vaginal cerclage.

What are the risks of cerclage?

Although cerclage is generally a safe procedure, the following complications may occur:

• Vaginal bleeding
• Infection
• Premature rupture of the membranes
• Uterine contractions
• Injury to the cervix
• Displacement of the stitch
• Bladder injury
• Preterm birth or pregnancy loss despite cerclage

The level of risk is not the same for planned and emergency cerclages. When the cervix has already opened and the amniotic sac has moved downward, emergency cases can carry a higher risk of complications.

When might cerclage not be performed?

Cerclage may not be appropriate in the following situations:

• Active intrauterine or vaginal infection
• Regular uterine contractions and active labor
• Significant vaginal bleeding
• Ruptured membranes
• Certain situations in which continuing the pregnancy is not medically appropriate

In multiple pregnancies, routine cerclage based solely on a short cervix is not recommended. The decision should be individualized according to the patient’s clinical condition.

What should you pay attention to after cerclage?

For a few days after the procedure, mild cramping, spotting or vaginal discharge may occur. Follow the recommendations of the doctor who performed the procedure regarding heavy physical activity, sexual intercourse and returning to daily life.

If you have any of the following symptoms, seek medical care without delay:

• Regular or increasing contractions
• Severe abdominal or back pain
• Persistent or heavy vaginal bleeding
• Leakage of fluid
• Fever
• Foul-smelling or green vaginal discharge
• A marked decrease in the baby’s movements

Prolonged routine bed rest is not recommended to prevent preterm birth.

When is the cerclage stitch removed?

A transvaginal cerclage stitch is usually removed at 36–37 weeks of pregnancy. The stitch may need to be removed earlier in situations such as the onset of labor or rupture of the membranes.

After the stitch is removed, if there is no other obstacle, a vaginal birth may be possible.

A transabdominal cerclage, on the other hand, is usually not removed. Birth is by caesarean section and the stitch can be left in place for future pregnancies.

Is cerclage needed again in the next pregnancy?

Having had a cerclage in one pregnancy does not mean that a cerclage will necessarily be needed in every future pregnancy.

The following factors are considered when deciding:

• The reason for the previous cerclage
• The cerclage method used
• The week of pregnancy at which birth occurred
• How the previous pregnancy ended
• The current anatomy of the cervix
• Whether the vaginal cerclage was successful

Women with a history of second-trimester pregnancy loss, very early preterm birth or cerclage should, if possible, be assessed before pregnancy or in the early weeks of pregnancy for the best planning.

Frequently asked questions about cervical insufficiency and cerclage

Can cervical insufficiency be detected during pregnancy?

Yes. It can be detected during pregnancy through previous pregnancy history, cervical measurement with transvaginal ultrasound and physical examination. However, in some patients the first sign may be painless opening of the cervix or a late pregnancy loss.

Can cervical insufficiency be completely prevented?

Not every case can be prevented. Early identification of high-risk patients, serial cervical measurements, progesterone or cerclage in suitable patients and choosing single embryo transfer in IVF treatment can reduce the risk.

If the cervix is under 25 mm, is cerclage always needed?

No. A cervix of twenty-five millimeters or less can be considered short; however, in patients without a history of preterm birth and without cervical opening, the first approach is usually vaginal progesterone.

Is cerclage performed if the cervix is under 10 mm?

If the cervix has shortened to below 10 mm despite progesterone treatment, cerclage may be considered on an individual basis. However, the week of pregnancy, cervical opening and signs of infection must also be taken into account.

Does cerclage definitely prevent preterm birth?

No. Cerclage does not definitely prevent all preterm births or pregnancy losses. In the right patient, it can help the pregnancy reach later weeks by reducing the risk.

Is double embryo transfer performed in cervical insufficiency?

Although it is not defined as an absolute prohibition, in patients with cervical insufficiency or a serious history of preterm birth double embryo transfer is not recommended. Single embryo transfer should be prioritized to reduce the risk of multiple pregnancy.

Is routine cerclage performed in twin pregnancies?

No. In twin pregnancies, routine cerclage based solely on a short cervix is not recommended. In special situations such as marked cervical opening, the decision can be individualized.

Up to which week can cerclage be performed?

Planned and ultrasound-indicated vaginal cerclages are usually performed before 24 weeks of pregnancy. For emergency cerclage too, the evidence is strongest before 24 weeks.

Is a normal birth possible after cerclage?

After a transvaginal cerclage stitch is removed, a vaginal birth is possible if there is no other obstacle. In patients with a transabdominal cerclage, however, birth is by caesarean section.

Is bed rest needed after cerclage?

Prolonged routine bed rest is generally not recommended. The level of activity should be determined by the patient’s clinical condition and the doctor’s recommendations.

Conclusion

Cervical insufficiency is an important pregnancy complication that can be managed with personalized follow-up and treatment when recognized early. The timing, method and surgical technique of cerclage are not the same for every patient.

In most patients transvaginal cerclage is sufficient, while in selected patients who have had a very early preterm birth despite a previous vaginal cerclage, or in whom vaginal cerclage is not possible, abdominal cerclage may be considered.

A cervical length of 25 mm or less is considered a short cervix, but the cerclage decision is not made on this measurement alone. Previous pregnancy history, cervical opening, signs of infection and the week of pregnancy should be evaluated together.

In IVF patients with cervical insufficiency or a serious history of preterm birth, to avoid multiple pregnancy, single embryo transfer should be considered first.

If you have a history of second-trimester pregnancy loss, very early preterm birth or cervical cerclage, for a detailed assessment before pregnancy or in the early weeks of pregnancy you can consult an obstetrician and gynecologist.

Author and medical review:
Op. Dr. Soner Duzguner
Obstetrics, Gynecology and IVF Specialist
Last updated: August 28, 2026

This content has been prepared for general information purposes. It does not replace an examination, diagnosis or personalized treatment advice.