What is the appropriate management for a 10‑week pregnant woman with a prior painless second‑trimester loss at 18 weeks suggestive of cervical insufficiency?

Management of Subsequent Pregnancy After Prior Painless Second-Trimester Loss at 18 Weeks

Serial transvaginal ultrasound assessment of cervical length starting at 14-16 weeks is the recommended approach, with ultrasound-indicated cerclage placement only if the cervix shortens to ≤25 mm before 24 weeks. 1

Rationale for Serial Ultrasound Over Prophylactic Cerclage

The patient's history of a single painless second-trimester loss at 18 weeks is suggestive of cervical insufficiency, but does not meet criteria for history-indicated (prophylactic) cerclage. 1

• History-indicated cerclage at 12-14 weeks is reserved exclusively for women with ≥3 prior second-trimester losses or extreme premature deliveries without other identifiable causes. 1, 2
• With only one prior loss, this patient falls into the intermediate-risk category requiring surveillance rather than automatic intervention. 1
• Approximately 69% of high-risk women maintain cervical length >25 mm throughout pregnancy and never require cerclage. 1

Serial Ultrasound Surveillance Protocol

Begin transvaginal ultrasound cervical length measurements at 14-16 weeks of gestation and continue every 1-2 weeks through 24 weeks. 1

• Transvaginal ultrasound is the reference standard for cervical assessment, superior to clinical examination alone. 1
• A cervical length ≤25 mm before 24 weeks is the threshold for intervention. 1
• If cervical length remains >25 mm throughout surveillance, no cerclage is needed. 1

Intervention Thresholds Based on Ultrasound Findings

If Cervical Length ≤25 mm but >10 mm:

• Offer ultrasound-indicated cerclage placement through shared decision-making. 1
• Initiate vaginal progesterone 200 mg daily as first-line therapy. 1
• Vaginal progesterone reduces spontaneous preterm birth at <34 weeks and improves neonatal outcomes. 1

If Cervical Length <10 mm:

• Strongly recommend ultrasound-indicated cerclage, as this threshold shows particular benefit with decreased preterm birth at <35 weeks (39.5% vs 58.0%). 1
• Add vaginal progesterone 200 mg daily after cerclage placement, as one study demonstrated reduced spontaneous preterm birth at <34 weeks (2.2% vs 18.4%) and <37 weeks (9.1% vs 29.7%). 1

Critical Pitfalls to Avoid

• Do not place cerclage at arbitrary gestational ages (13 or 15 weeks) without objective cervical shortening documented by ultrasound. 1
• Clinical cervical examination alone is insufficient for risk stratification—transvaginal ultrasound provides superior predictive value. 1
• Do not use 17-alpha hydroxyprogesterone caproate for short cervix treatment. 1
• Do not place cervical pessary due to conflicting trial data and recent safety signals. 1

Additional Management Considerations

• Screen for and treat any genitourinary infections at the first prenatal visit, including urinalysis with culture and vaginal cultures for bacterial vaginosis. 2
• Permit routine daily activities and light upper-body resistance exercise, but avoid moderate-to-vigorous physical activity both before and after any cerclage placement. 1
• Do not prescribe bed rest—it offers no benefit and may be harmful. 1
• Educate the patient to report immediately any signs of preterm labor (contractions, pelvic pressure, vaginal bleeding, fluid leakage) or infection (fever, uterine tenderness, purulent discharge). 1

Why Reassurance Alone Is Inadequate

Simple reassurance (Option A) ignores the established 25-50% recurrence risk after one prior second-trimester loss due to cervical insufficiency and fails to provide evidence-based surveillance. 3 The history of painless cervical dilation and delivery at 18 weeks is characteristic of cervical insufficiency, warranting structured monitoring rather than expectant management alone. 3

Answer: D. Serial ultrasound for progress is the evidence-based approach, with intervention (cerclage and/or progesterone) reserved for objective cervical shortening documented by ultrasound surveillance. 1