What is the recommended approach for a patient with a history of one second trimester abortion presenting for counseling about a second pregnancy?

Management of Second Pregnancy After One Second Trimester Loss

Serial ultrasound monitoring of cervical length starting at 16-18 weeks is the recommended approach, with ultrasound-indicated cerclage placement only if cervical shortening is detected (cervical length <25mm). 1

Rationale Against Prophylactic Cerclage at 13 Weeks

A single second trimester loss does NOT meet criteria for history-indicated cerclage. The Society for Maternal-Fetal Medicine and major guidelines reserve history-indicated cerclage for women with three or more prior second trimester losses or preterm births due to painless cervical dilation, or classic features of cervical insufficiency. 1, 2

• History-indicated cerclage should be reserved for individuals with classic historical features of cervical insufficiency or an unexplained second-trimester loss in the absence of placental abruption. 1
• Prophylactic cerclage at 13 weeks in this patient would be premature and not evidence-based, as one loss alone does not establish cervical insufficiency. 2, 3
• Cerclage placement after previable PPROM was associated with increased odds of preterm birth (63.2% vs 10.9%; OR 14.0) in subsequent pregnancies, highlighting the importance of proper patient selection. 1

Recommended Surveillance Strategy

Serial transvaginal ultrasound (TVUS) cervical length screening is the evidence-based approach for this patient:

• Begin TVUS screening at 16-18 weeks gestation and continue every 1-2 weeks until 24 weeks. 1
• Cervical length <25mm is the threshold for intervention consideration. 1
• TVUS is highly reproducible and identifies changes at the internal os where preterm birth risk first manifests. 1

Intervention Based on Ultrasound Findings

If cervical shortening is detected (<25mm):

• Ultrasound-indicated cerclage reduces preterm birth by 30% before 35 weeks in high-risk patients with short cervical length. 1
• Alternative interventions include vaginal progesterone (44% reduction in PTB <34 weeks) or cervical pessary (78% reduction in PTB <34 weeks). 1
• The decision between cerclage, progesterone, or pessary should incorporate the specific cervical length measurement, presence of funneling, and patient history. 1

Why Clinical Assessment Alone is Insufficient

Digital cervical examination is not recommended as the primary screening method because:

• TVUS is superior to digital examination for detecting early cervical changes. 1
• By the time cervical dilation is clinically apparent, the window for effective intervention may have passed. 1
• TVUS provides objective, reproducible measurements that guide evidence-based interventions. 1

Critical Timing Considerations

• Do not place cerclage at 18 weeks routinely without documented cervical shortening, as this represents therapeutic/urgent cerclage timing but requires ultrasound evidence of cervical insufficiency. 4
• Cerclage placement between 13-16 weeks is reserved for history-indicated cases (≥3 prior losses), which this patient does not meet. 4, 2
• If cervical shortening is detected on surveillance ultrasound, cerclage can be placed as ultrasound-indicated (therapeutic) cerclage at that time. 1, 2

Additional Management Recommendations

Follow guidelines for management of pregnant persons with previous spontaneous preterm birth:

• Offer vaginal progesterone supplementation starting at 16-24 weeks if cervical shortening develops. 1
• Provide counseling about warning signs of preterm labor and cervical insufficiency. 1
• Ensure access to maternal-fetal medicine consultation if cervical changes are detected. 1