Maintaining quality assurance for sonographic nuchal translucency measurement: lessons from the FASTER Trial

Objective To evaluate nuchal translucency measurement quality assurance techniques in a large‐scale study. Methods From 1999 to 2001, unselected patients with singleton gestations between 10 + 3 weeks and 13 + 6 weeks were recruited from 15 centers. Sonographic nuchal translucency measurement was performed by trained technicians. Four levels of quality assurance were employed: (1) a standardized protocol utilized by each sonographer; (2) local‐image review by a second sonographer; (3) central‐image scoring by a single physician; and (4) epidemiological monitoring of all accepted nuchal translucency measurements cross‐sectionally and over time. Results Detailed quality assessment was available for 37 018 patients. Nuchal translucency measurement was successful in 96.3% of women. Local reviewers rejected 0.8% of images, and the single central physician reviewer rejected a further 2.9%. Multivariate analysis indicated that higher body mass index, earlier gestational age and transvaginal probe use were predictors of failure of nuchal translucency measurement and central image rejection (P = 0.001). Epidemiological monitoring identified a drift in measurements over time. Conclusion Despite initial training and continuous image review, changes in nuchal translucency measurements occur over time. To maintain screening accuracy, ongoing quality assessment is needed. Copyright © 2009 ISUOG. Published by John Wiley & Sons, Ltd.