What are the indications for cervical cerclage (cervical circumferential suture)?

From the Guidelines

Cervical cerclage is indicated for women with a history of cervical insufficiency, including those with a history of painless cervical dilation in the second trimester leading to pregnancy loss, a history of spontaneous preterm birth before 34 weeks, or a short cervical length (less than 25 mm) detected on ultrasound before 24 weeks of pregnancy, particularly in women with previous preterm births 1. The primary indications for cervical cerclage include:

• A history of painless cervical dilation in the second trimester leading to pregnancy loss
• A history of spontaneous preterm birth before 34 weeks
• A short cervical length (less than 25 mm) detected on ultrasound before 24 weeks of pregnancy, particularly in women with previous preterm births Cerclage may also be performed as an emergency procedure when cervical dilation is discovered during a routine examination in the second trimester (rescue cerclage) 1. Women with multiple gestations generally do not benefit from cerclage. The procedure involves placing a strong suture around the cervix to provide mechanical support and prevent premature dilation. Timing is crucial, with elective cerclage typically performed between 12-14 weeks, and ultrasound-indicated cerclage before 24 weeks 1. The suture is usually removed around 36-37 weeks of pregnancy or when labor begins. Cerclage works by providing physical support to the cervix, preventing it from opening prematurely due to the increasing weight of the growing pregnancy, thereby reducing the risk of preterm birth in appropriately selected patients. It is essential to note that cerclage placement in individuals without a history of preterm birth who have a sonographic short cervix (10-25 mm) is not recommended in the absence of cervical dilation, as stated in the SMFM Consult Series #70 1. In contrast, vaginal progesterone is recommended for asymptomatic individuals with a singleton gestation and a transvaginal cervical length of 20 mm diagnosed before 24 weeks of gestation to reduce the risk of preterm birth 1. Key considerations for cerclage placement include:
• History of cervical insufficiency
• History of spontaneous preterm birth
• Short cervical length detected on ultrasound
• Presence of cervical dilation
• Gestational age at the time of cerclage placement
• Presence of multiple gestations
• Use of vaginal progesterone as an alternative or adjunct to cerclage.

From the Research

Indications for Cervical Cerclage

The following are indications for cervical cerclage:

• Women with a history of three or more second-trimester pregnancy losses or extreme premature deliveries, in whom no specific cause other than potential cervical insufficiency is identified, should be offered elective cerclage at 12 to 14 weeks of gestation 2, 3, 4, 5
• Women with a history of spontaneous preterm birth or possible cervical insufficiency if the cervical length is ≤ 25 mm before 24 weeks of gestation 2, 3, 5
• Women who have undergone trachelectomy should have abdominal cerclage placement 2
• Emergency cerclage may be considered in women in whom the cervix has dilated to < 4 cm without contractions before 24 weeks of gestation 2
• Women with a classic history of cervical insufficiency in whom prior vaginal cervical cerclage has been unsuccessful, abdominal cerclage can be considered in the absence of additional mitigating factors 2, 6, 5

Specific Guidelines

• The American College of Obstetricians and Gynecologists (ACOG), the Royal College of Obstetricians and Gynaecologists (RCOG), the Society of Obstetricians and Gynaecologists of Canada (SOGC), and the International Federation of Gynecology and Obstetrics (FIGO) have published guidelines on the indications, contraindications, techniques, and timing of placing and removal of cervical cerclage 3, 5
• A history-indicated cerclage should be offered to women who have had three or more preterm deliveries and/or mid-trimester losses 3, 5
• An ultrasound-indicated cerclage should be offered to women with a cervical length <25 mm if they have had one or more spontaneous preterm birth and/or mid-trimester loss 3, 5

Contraindications and Special Considerations

• There is no benefit to cerclage in a woman with an incidental finding of a short cervix by ultrasound examination but no prior risk factors for preterm birth 2
• Present data do not support the use of elective cerclage in multiple gestations even when there is a history of preterm birth 2, 3
• The literature does not support the insertion of cerclage in multiple gestations on the basis of cervical length 2, 3