What is the management for a patient with a short cervix?

Management of Short Cervix in Pregnancy

For patients with a short cervix (≤25 mm) in singleton pregnancies without a history of spontaneous preterm birth, vaginal progesterone is the recommended first-line intervention, with specific management determined by the exact cervical length measurement. 1

Diagnosis of Short Cervix

• Definition: A cervical length ≤25 mm before 24 weeks of gestation is considered short in singleton gestations 1, 2
• Measurement technique:
  • All cervical length measurements must be performed using a transvaginal approach following standardized procedures 1
  • Transabdominal assessment is standard during routine ultrasound but is less reliable for accurate cervical length measurement 2
  • If transabdominal assessment is inadequate or suspicious for abnormality, transvaginal ultrasound is required 2

Management Algorithm for Short Cervix

For Singleton Pregnancies Without Prior Preterm Birth:

1. Cervical length ≤20 mm before 24 weeks:

   • Prescribe vaginal progesterone to reduce preterm birth risk (GRADE 1A evidence) 1
   • Dosing options: 90-200 mg daily until 36 weeks or delivery

2. Cervical length 21-25 mm before 24 weeks:

   • Consider vaginal progesterone based on shared decision-making (GRADE 1B evidence) 1
   • Discuss risks/benefits with patient

3. Interventions NOT recommended:

   • 17-alpha hydroxyprogesterone caproate (including compounded formulations) 1
   • Cerclage placement in the absence of cervical dilation (for cervical length 10-25 mm) 1
   • Cervical pessary 1

For Twin Pregnancies:

• Progesterone, pessary, or cerclage are NOT recommended for treatment of cervical shortening in twin gestations outside clinical trials (GRADE 1B evidence) 1, 2
• Twin pregnancies have naturally shorter cervical lengths than singleton pregnancies 2

Important Clinical Considerations

• Transvaginal ultrasound cervical length assessment is one of the best clinical predictors of spontaneous preterm birth 1
• The risk of preterm delivery is inversely correlated with cervical length 3
• Short cervix is associated with significant perinatal morbidity and mortality due to preterm birth 1
• Cervical length screening should be performed between 18-24 weeks of gestation 2, 4

Pitfalls and Caveats

• Transabdominal cervical length measurement is less accurate and may overestimate cervical length compared to transvaginal measurement 2
• Despite treatment with vaginal progesterone, patients with short cervix remain at elevated risk for preterm birth and should be monitored closely 5
• The positive predictive value of a midtrimester cervical length ≤25 mm for spontaneous preterm birth before 37 weeks is only 16.2%, and for birth before 32 weeks is 7.4% 1
• Patients with additional risk factors (prior cervical procedures, uterine anomalies) may require more aggressive management 2
• The etiology of short cervix is multifactorial, and cervical shortening represents the final common pathway for several causes of preterm delivery 6

Follow-up Recommendations

• Serial cervical length measurements may be indicated for patients with borderline short cervix
• Patients with short cervix should be counseled about signs and symptoms of preterm labor
• Consider antenatal corticosteroids if preterm birth appears imminent
• Referral to maternal-fetal medicine specialist is appropriate for complex cases