When is a cervical cerclage indicated in a pregnant woman with a history of cervical insufficiency or preterm birth?

History-Indicated Cervical Cerclage: Clinical Indications

History-indicated cerclage should be placed at 12-14 weeks of gestation in women with three or more second-trimester pregnancy losses or extreme premature deliveries without other identifiable causes, or in those with classic features of cervical insufficiency such as prior painless cervical dilation leading to second-trimester loss. 1, 2

Primary Indications for History-Indicated Cerclage

Classic Cervical Insufficiency

• The strongest indication is three or more second-trimester pregnancy losses or extreme premature deliveries where no specific cause other than cervical insufficiency has been identified 1, 3
• Classic presentation includes prior second-trimester loss (typically around 18 weeks) with painless cervical dilation in the absence of labor, rupture of membranes, or placental abruption 2, 4
• History-indicated cerclage should be reserved for individuals with these classic historical features or unexplained second-trimester loss 4

Optimal Timing

• Place cerclage at 12-14 weeks of gestation, which allows completion of first-trimester organogenesis while intervening before typical cervical changes occur 2, 3
• Waiting until the gestational age of prior loss (e.g., 18 weeks) is too late, as cervical changes may already be underway, potentially requiring emergency cerclage with worse outcomes 2

Alternative Indications Based on Ultrasound Findings

Ultrasound-Indicated Cerclage

• For women with prior spontaneous preterm birth AND cervical length ≤25 mm before 24 weeks, cerclage placement is strongly supported by compelling data 1, 3
• This represents a distinct indication from history-indicated cerclage and requires both risk factors to be present 5

Extremely Short Cervix Exception

• In women with cervical length <10 mm, cerclage may be considered even without prior preterm birth history based on shared decision-making, as subgroup analysis showed decreased preterm birth at <35 weeks (39.5% vs 58.0%; RR 0.68) 1
• For progressive cervical shortening to <10 mm despite vaginal progesterone, limited evidence suggests benefit of adding cerclage (delivery at 34 3/7 vs 27 2/7 weeks) 1

When History-Indicated Cerclage is NOT Indicated

Insufficient Historical Criteria

• Women with only one or two prior second-trimester losses should receive serial cervical length assessment by ultrasound rather than automatic cerclage placement 3
• Prior uterine surgeries (myomectomies, hysteroscopies) without history of spontaneous preterm birth do not indicate cervical insufficiency 6

Normal Cervical Length Without Risk Factors

• Cerclage is NOT indicated for women without history of preterm birth who have sonographic short cervix (10-25 mm) 1, 6
• Incidental finding of short cervix on ultrasound without prior risk factors for preterm birth does not warrant cerclage 3

Multiple Gestations

• Present data do not support elective cerclage in multiple gestations even with history of preterm birth, and this should be avoided 3
• Cerclage in twins is not supported even when cervical length is short 3

Special Circumstances

Prior Previable PPROM

• After a history of previable or periviable preterm prelabor rupture of membranes (PPROM), history-indicated cerclage should be reserved for individuals with classic historical features of cervical insufficiency or unexplained second-trimester loss in the absence of placental abruption 4
• One study showed cerclage placement after prior previable PPROM was associated with increased odds of preterm birth (63.2% vs 10.9%; OR 14.0), encouraging caution 4

Prior Cerclage for Non-Traditional Indications

• In women with prior cerclage for indications other than classic cervical insufficiency, repeat history-indicated cerclage may not improve outcomes compared with serial ultrasound cervical length monitoring 7
• Consider ultrasound-indicated approach rather than automatic repeat cerclage 7

Physical Examination-Indicated (Emergency) Cerclage

• Emergency cerclage may be considered when cervix has dilated to <4 cm without contractions before 24 weeks of gestation 3
• This represents a third distinct indication separate from history-indicated and ultrasound-indicated cerclage 5

Post-Cerclage Management

• Consider 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%) 2
• Serial cervical length assessments are NOT routinely recommended after cerclage placement due to insufficient evidence supporting clinical benefit 1, 2

Critical Pitfall to Avoid

The most common error is placing history-indicated cerclage based on insufficient historical criteria (e.g., single prior loss, uterine surgery history alone, or short cervix without prior preterm birth). These scenarios require either ultrasound-indicated approach or serial monitoring rather than automatic cerclage placement 1, 6, 3.