Is cerclage recommended for a patient with a short cervix but no history of preterm birth?

Cerclage for Short Cervix Without Previous Preterm Birth

Cerclage is not recommended for patients with a short cervix who have no history of spontaneous preterm birth. 1

Evidence-Based Management of Short Cervix

The Society for Maternal-Fetal Medicine (SMFM) provides clear guidance on this issue in their 2024 recommendations. For patients without a history of preterm birth who have a sonographic short cervix (10-25 mm), cerclage placement is specifically not recommended in the absence of cervical dilation (GRADE 1B) 1.

Diagnostic Criteria

• A short cervix is defined as a midtrimester cervical length of ≤25 mm in individuals with singleton gestation 1
• All cervical length measurements should be performed using transvaginal ultrasound following standardized procedures 1

Recommended Management Algorithm

1. For cervical length ≤20 mm before 24 weeks' gestation:

   • Vaginal progesterone is strongly recommended (GRADE 1A) 1
   • Cerclage should NOT be placed 1

2. For cervical length 21-25 mm:

   • Consider vaginal progesterone based on shared decision-making (GRADE 1B) 1
   • Cerclage should NOT be placed 1

3. For extremely short cervix <10 mm:

   • While cerclage is generally not recommended, it may be considered in this specific subgroup
   • A planned subgroup analysis showed a decrease in preterm birth at <35 weeks with cerclage in this extreme subgroup (39.5% vs 58.0%; RR, 0.68; 95% CI, 0.47-0.98) 1

4. For twin gestations with short cervix:

   • Neither progesterone, pessary, nor cerclage is recommended outside clinical trials (GRADE 1B) 1

Supporting Evidence

The recommendation against cerclage is based on multiple studies showing lack of benefit in this population:

• A meta-analysis of 5 randomized trials with 419 asymptomatic patients with cervical length <25 mm and no previous preterm birth found no difference in preterm birth rates at <35 weeks of gestation between cerclage and no cerclage groups 1

• A multicenter randomized controlled trial of 253 women with very short cervical length (<15 mm) showed no improvement in preterm birth rates with cerclage placement (22% vs 26%; RR, 0.84; 95% CI, 0.54-1.31) 2

Important Considerations and Pitfalls

1. Do not confuse with history-indicated cerclage:

   • Cerclage has demonstrated benefit in women with prior preterm births or mid-trimester losses, but this does not extend to those without such history 3

2. Avoid unnecessary surgical intervention:

   • Cerclage carries risks including rupture of membranes, infection, and cervical trauma
   • Unnecessary cerclage may lead to iatrogenic complications without improving outcomes

3. Alternative management:

   • Vaginal progesterone is the preferred treatment for short cervix without prior preterm birth 1, 4
   • 17-alpha hydroxyprogesterone caproate should NOT be prescribed for short cervix (GRADE 1B) 1
   • Cervical pessary is not recommended for prevention of preterm birth in singleton gestations with short cervix (GRADE 1B) 1

4. Special circumstances:

   • If progressive cervical shortening to <10 mm occurs despite vaginal progesterone, cerclage may be considered based on shared decision-making, though evidence is limited 1
   • If cervical dilation with membrane exposure is present, a "rescue cerclage" may be considered on an individual basis, though this carries higher risks 3

In conclusion, for patients with a short cervix but no history of preterm birth, vaginal progesterone is the evidence-based treatment of choice, while cerclage should be avoided except in very specific circumstances.