Role of Routine Cervical Length Screening in Low-Risk Nulliparous Women at Midgestation

Abstract

Introduction: Universal cervical length screening at 18–24 weeks detects short cervix and prevents preterm birth via progesterone. However, most studies included high-risk populations. This review examines benefit in low-risk nulliparas.
Methods: Literature search for studies of universal transvaginal cervical length screening versus risk-factor-based screening in nulliparous women without prior preterm birth. Outcome: spontaneous preterm birth <37 weeks and <34 weeks.
Results: Five studies (two randomized, three cohort; total n=85,000) were included. Universal screening detected short cervix (<25 mm) in 1.2% of low-risk nulliparas. The number needed to screen to prevent one preterm birth <34 weeks was 430. Universal screening reduced preterm birth <34 weeks by 22% compared to risk-based screening.
Discussion: The absolute benefit is modest but statistically significant. Cost-effectiveness models vary. Universal screening increases anxiety and interventions (progesterone use) in many who would not have delivered early.
Conclusions: Universal cervical length screening in low-risk nulliparas reduces early preterm birth modestly. Implementation depends on healthcare system resources and patient values regarding overdiagnosis.