Cervical insufficiency revisited: a proposal for a new treatment-aligned definition

Cervical insufficiency [CI] has traditionally been defined as painless cervical dilation resulting in recurrent second-trimester pregnancy loss in the absence of labor or placental pathology. Definitions from the American College of Obstetricians and Gynecologists and the Royal College of Obstetricians and Gynecologists emphasize historical clinical presentation. However, contemporary obstetrics relies increasingly on ultrasound-based cervical length surveillance and evidence-based cerclage indications rather than retrospective diagnosis. The objective of the review was to propose a definition of cervical insufficiency aligned with current evidence-based indications for mechanical prevention of preterm birth, i.e. cervical cerclage. In modern obstetric practice, the operational diagnosis of clinically significant cervical dysfunction is determined by whether a patient meets criteria for cerclage (history-indicated, ultrasound-indicated, or physical examination-indicated). Thus, treatment thresholds have effectively supplanted historical definitions in guiding care. We propose redefining cervical insufficiency for singleton gestations as a clinical condition in which a pregnant patient meets established evidence-based criteria for cervical cerclage placement in the absence of active preterm labor or intra-amniotic infection. This treatment-aligned definition better reflects contemporary practice, enhances diagnostic clarity, and may improve consistency in clinical care and research.