Implementing a Universal Cervical Length Screening Program in a Large Hospital System: It Takes Some Time to Achieve Consistent Results

Abstract

Objective: The aim of the study was to describe changes in the acceptance of transvaginal (TV) cervical length (CL) assessment and in the variance of CL measurements among operators, after implementation of universal TV-CL screening at 18+0 – to 23+6 weeks/days of gestation. Design: Retrospective cohort. Participants/Materials, Setting, Methods: This study was performed after universal TV-CL screening was implemented at the University of Texas Health Science Center in Houston, TX, USA, for all women undergoing an anatomy ultrasound (US) between 18 0/6 and 23 6/7 weeks/days of gestation. Pregnant women carrying singletons without prior history of preterm delivery who underwent anatomy US evaluation between September 2017 and March 2020 (30 months) were included. The complete study period was divided into five epochs of 6 months each. Changes in patient’s acceptance for the TV scan, in CL distribution, in the prevalence of short cervix defined as ≤15, ≤20, or ≤25 mm, and in the performance of US operators across the five epochs were evaluated. Success rate was defined as the percentage of TV-CL measurements obtained in relation to the number of second-trimester anatomy scans. Results: A total of 22,207 low-risk pregnant women evaluated by 36 trained sonographers (operators) were analyzed. Overall, the acceptance for TV-CL measurement was 82.3% (18,289/22,207), increasing from 76.7% in the first epoch to 82.8% (p < 0.0001) in the last epoch. The mean CL did not significantly change from 38.6 mm in the first epoch to 38.5 mm in the last epoch (p = 0.7); however, the standard deviation decreased from 7.9 mm in the first epoch to 7.04 mm in the last epoch (p = <0.01). The prevalence of a short cervix ≤25 mm was 2.2% (n = 399/18,289), ≤20 mm was 1.2% (224/18,289), and ≤15 mm was 0.9% (162/18,289). This prevalence varied only for CL ≤25 mm from 3.02% (88/2,907) in the first epoch to 1.77% (64/3,615) in the last epoch (p = 0.0009). There was a variation in CL measurements among operators (mean 3.3 mm). Sonographers with less than 1 year of experience had a lower success rate for completing TV-CL examinations than more experienced sonographers (80.8% vs. 85.8%; p < 0.03). In general, 77% (27/35) of operators had a success rate ≥80% for completing TV-CL scans. Limitations: Characteristics of individuals who accepted versus those who declined TV-CL were not compared; CL values were not correlated with clinical outcomes. Conclusions: During the first 6 months after implementation of a universal CL screening program, there was greater variation in CL measurements, lower acceptance for TV US, and a higher number of women diagnosed with a CL ≤25 mm, as compared to subsequent epochs. After the first 6 months, these metrics improved and remained stable. Most operators improved their performance over time; however, there were a few with a low success rate for TV-CL and others who systematically over- or underestimate CL measurements.