Timing of Cervical Cerclage at 13-16 Weeks
History-indicated cerclage is placed at 12-14 weeks (not 13-16 weeks) because this timing allows placement after first-trimester organogenesis is complete but before typical cervical changes begin, maximizing effectiveness while minimizing the risk of intervening on a pregnancy destined to miscarry for other reasons. 1
Rationale for Early Second Trimester Placement
The optimal window of 12-14 weeks represents a critical balance:
After organogenesis: Placement after 12 weeks avoids intervening during the period of major fetal organ development, reducing the risk of placing cerclage in pregnancies with lethal anomalies that would miscarry regardless 1
Before cervical changes: Waiting until 18 weeks or later is too late, as cervical changes associated with insufficiency may already be underway, making the procedure less effective and potentially requiring emergency cerclage placement under suboptimal conditions 1
Standard practice: No guideline recommends delaying cerclage until the gestational age of prior pregnancy loss 1
Types of Cerclage and Their Timing
History-Indicated Cerclage (12-14 weeks)
Reserved for patients with three or more second-trimester pregnancy losses or extreme premature deliveries without other identifiable causes 2
Also indicated for patients with 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
Placement at 12-14 weeks is specifically recommended by ACOG for these high-risk patients 1
Ultrasound-Indicated Cerclage (14-24 weeks)
For patients with 1-2 prior second-trimester losses, serial transvaginal ultrasound assessment begins at 14-16 weeks 3
Cerclage is placed only if cervical length shortens to ≤25 mm before 24 weeks 3
This approach avoids unnecessary surgery in approximately 69% of high-risk women who maintain adequate cervical length 3
Examination-Indicated Cerclage (Before 24 weeks)
- Placed when cervical dilation is detected on physical examination before 24 weeks, particularly when cervical length measures <11-15 mm on ultrasound 3
Common Pitfalls to Avoid
Do not place cerclage at arbitrary gestational ages without objective assessment 3. The timing should be guided by:
- Patient's specific history (history-indicated at 12-14 weeks for multiple losses) 1
- Ultrasound findings (ultrasound-indicated when cervix shortens to ≤25 mm) 3
- Physical examination findings (examination-indicated when dilation detected) 3
Do not delay history-indicated cerclage until the gestational age of prior loss, as this defeats the purpose of prophylactic intervention 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, 3
Serial ultrasound monitoring is NOT routinely recommended after history-indicated cerclage placement, as insufficient evidence supports clinical benefit 1, 3
Permit routine daily activities and light upper-body resistance exercise, but avoid moderate-to-vigorous physical activity 3
Never prescribe bed rest, as it offers no benefit and may be harmful 3