At what gestational age is cervical cerclage typically performed in pregnant women with a history of cervical insufficiency or preterm labor?

Timing of Cervical Cerclage Placement

Cervical cerclage is performed at different gestational ages depending on the clinical indication: history-indicated cerclage at 12-14 weeks, ultrasound-indicated cerclage when cervical shortening ≤25 mm is detected before 24 weeks (typically monitored starting at 14-16 weeks), and examination-indicated cerclage when cervical dilation is detected on physical exam before 24 weeks. 1, 2

History-Indicated Cerclage (Prophylactic)

Place at 12-14 weeks of gestation for women meeting specific high-risk criteria: 1, 2, 3

• Three or more second-trimester pregnancy losses or extreme premature deliveries without other identifiable causes 1, 3
• Classic features of cervical insufficiency, such as prior second-trimester loss with painless cervical dilation in the absence of labor, rupture of membranes, or placental abruption 2, 4
• This timing allows placement after first-trimester organogenesis but before typical cervical changes occur 2
• Do not delay cerclage until the gestational age of prior loss—waiting until 18 weeks is too late, as cervical changes may already be underway 2

Ultrasound-Indicated Cerclage

Begin serial transvaginal ultrasound cervical length screening at 14-16 weeks in women with 1-2 prior spontaneous preterm births or second-trimester losses: 1

• Place cerclage when cervical length shortens to ≤25 mm before 24 weeks of gestation 1, 3, 5
• Cerclage shows particular benefit when cervical length is <10 mm, with decreased preterm birth at <35 weeks (39.5% vs 58.0%) 1, 4
• Continue monitoring through 24 weeks, as approximately 69% of high-risk women maintain cervical length >25 mm and do not require cerclage 6
• Transvaginal ultrasound is the reference standard, superior to clinical examination alone 1

Examination-Indicated Cerclage (Emergency)

Place when cervical dilation is detected on physical examination before 24 weeks of gestation: 1, 3

• Particularly indicated when cervical length measures <11-15 mm on ultrasound, as 30-70% of these patients will have cervical dilation ≥1 cm 1
• May be considered in women with cervical dilation <4 cm without contractions before 24 weeks 3
• This represents the most urgent indication for cerclage placement 7, 5

Critical Pitfalls to Avoid

• Do not place cerclage at arbitrary gestational ages without objective cervical assessment 1, 2
• Do not place cerclage routinely for cervical length 10-25 mm in women without prior preterm birth history—meta-analysis shows no benefit in this population 1, 4
• Do not use cerclage in multiple gestations, even with history of preterm birth or short cervix, as literature does not support benefit 3
• Clinical cervical dilation assessment alone is insufficient—always use transvaginal ultrasound for risk stratification 1

Post-Cerclage Management

Add vaginal progesterone 200 mg daily after cerclage placement, which reduces spontaneous preterm birth at <34 weeks (2.2% vs 18.4%) and <37 weeks (9.1% vs 29.7%): 1, 2, 4

• Serial ultrasound monitoring after cerclage placement is NOT routinely recommended due to insufficient evidence supporting clinical benefit 2, 4
• Cerclage is typically removed at 36-37 weeks or with onset of labor 3