Analysis of Quality of Nuchal Translucency Measurements

Objective: Quantitative analysis of the quality of nuchal translucency (NT) measurements. Methods: This is a retrospective single-center study. NT was measured according to the Fetal Medicine Foundation (FMF) criteria by 20 trained obstetricians (October 2003-November 2009). The performance of NT measurements was analyzed with regard to several quality control standards. Accuracy according to experience, professional profile, crown-rump length (CRL) values and FMF certification was statistically tested. Results: A total of 14,978 NT measurements were assessed. (1) The mean operator-specific median NT-MoM values was 0.98. (2) Mean percentage of cases >95th and <5th percentiles were 5.0 and 4.2% respectively. (3) Logarithmic mean and SD of the NT-MoM values were 0.00 and 0.13 respectively. (4) The DR for trisomy 21 at screening time was 90.7% for a FPR of 6.7% for standard screening strategy. (5) According to cumulative SUM (CUSUM) figures, the performance was more acceptable in FMF-certified operators. Operator experience, exclusive dedication to FM, FMF certification and a range of CRL values > 60 mm had a statistical impact improving these standards. Conclusion: Overall quality standards show optimal NT measurements in our unit. Experience a dedicated profile to fetal medicine ultrasound, CRL over 60 mm and FMF certification has a significant positive impact on the quality standards.