Definition of Cervical Insufficiency
Cervical insufficiency is a structural and functional deficit of the cervix characterized by premature, painless cervical dilation occurring alongside one or more mid-second trimester pregnancy losses without evidence of preterm labor, chorioamnionitis, or fetal chromosomal abnormalities. 1
Diagnostic Criteria
Cervical insufficiency is diagnosed based on:
Clinical history:
- History of recurrent second-trimester pregnancy losses
- History of extreme preterm deliveries
- Prior pregnancy losses characterized by painless cervical dilation
Sonographic findings:
Risk Factors
Patients at risk for cervical insufficiency include those with:
- Prior mid-trimester pregnancy losses
- Prior extreme preterm deliveries
- Previous cervical trauma (e.g., LEEP, cone biopsy)
- Prior cervical lacerations during delivery
- Congenital uterine anomalies
- Prior trachelectomy
- Exposure to diethylstilbestrol (DES)
Clinical Significance
Cervical insufficiency presents significant risks to fetal health as premature cervical dilation can lead to:
- Pre-viable delivery
- Increased perinatal morbidity and mortality
- Pregnancy loss in the second trimester
Management Options
Management depends on risk factors and clinical presentation:
For Women with History of Cervical Insufficiency:
- Elective cerclage: Recommended for women with three or more second-trimester losses or extreme preterm deliveries without other identifiable causes 2
- Vaginal progesterone: For women with short cervix (≤20 mm) before 24 weeks' gestation 1
- Serial cervical length monitoring: For women with 1-2 prior mid-trimester losses or extreme preterm deliveries 2
For Women with Short Cervix but No Prior History:
- Vaginal progesterone: Recommended for singleton pregnancies with cervical length ≤20 mm diagnosed before 24 weeks 1
- Consider progesterone: For cervical length 21-25 mm based on shared decision-making 1
- Against cerclage: Not recommended for women with incidental finding of short cervix without prior risk factors 2
Special Considerations:
- Abdominal cerclage: May be considered when prior vaginal cerclage has failed or after trachelectomy 2
- Emergency cerclage: May be considered when cervix has dilated to <4 cm without contractions before 24 weeks 2
- Multiple gestations: Cerclage is not recommended even with history of preterm birth or short cervix 2
Activity Recommendations
Women with cervical insufficiency should:
- Maintain activities of daily living
- Potentially complete light upper-body resistance exercise
- Avoid moderate-to-vigorous physical activity 1
- These recommendations also apply to women with prophylactic or rescue cervical cerclage in place
Monitoring
- Transvaginal ultrasound is the preferred method for cervical length assessment 1
- Serial cervical length measurements should be performed according to standardized procedures as described by organizations such as the Perinatal Quality Foundation or the Fetal Medicine Foundation 1
Pitfalls and Caveats
- Diagnostic challenges: The diagnosis remains largely clinical and based on history, as there is no definitive objective test
- Overdiagnosis: Not all cases of short cervix represent true cervical insufficiency
- Infection screening: Women with history of cervical insufficiency should be screened for urinary tract infections and bacterial vaginosis at first obstetric visit 2
- Cerclage timing: Elective cerclage is typically placed at 12-14 weeks of gestation 2
- 17-alpha hydroxyprogesterone caproate: Not recommended for treatment of short cervix 1
- Pessary: Not recommended for prevention of preterm birth in singleton gestations with short cervix 1
By understanding the definition, risk factors, and management options for cervical insufficiency, clinicians can better identify at-risk patients and implement appropriate interventions to reduce the risk of preterm birth and associated morbidity and mortality.