The grades of evidence (I-III) and levels of recommendation (A-C) are defined at the end of the "Major Recommendations" field
The following recommendations are based on limited or inconsistent scientific evidence (Level B):
- Serial assessments in low-risk women to screen for cervical insufficiency are of low yield and should not be done routinely.
- Serial ultrasound examinations should be considered in a patient with historical risk factors for cervical insufficiency and should be initiated between 16 and 20 weeks of gestation or later.
- An elective cerclage can be considered in a patient with a history of 3 or more unexplained midtrimester pregnancy losses or preterm deliveries.
- Women exposed to diethylstilbestrol (DES) in utero may be evaluated for cervical insufficiency using the same clinical criteria as nonexposed individuals.
The following recommendations are based primarily on consensus and expert opinion (Level C):
- The evaluation of a patient with cervical shortening or funneling should include a comprehensive ultrasonographic assessment of the fetus to rule out anomalies, as well as physical and laboratory assessments to rule out labor and chorioamnionitis.
- Given the advances in neonatal care and the potential maternal and fetal morbidity associated with cerclage, surgical correction of cervical insufficiency should be limited to pregnancies before fetal viability has been achieved.
Grades of Evidence
I: Evidence obtained from at least one properly designed randomized controlled trial.
II-1: Evidence obtained from well-designed controlled trials without randomization.
II-2: Evidence obtained from well-designed cohort or case–control analytic studies, preferably from more than one center or research group.
II-3: Evidence obtained from multiple time series with or without the intervention. Dramatic results in uncontrolled experiments also could be regarded as this type of evidence.
III: Opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert committees.
Levels of Recommendations
Level A — Recommendations are based on good and consistent scientific evidence.
Level B — Recommendations are based on limited or inconsistent scientific evidence.
Level C — Recommendations are based primarily on consensus and expert opinion.