Objectives: To evaluate and compare the performance of various quality control methods for nuchal translucency (NT) measurements.
Methods: Fetal NT measurements performed over a oneyear period in a single center were used for the study. The retrospective quality review methods proposed by the Fetal Medicine Foundation (FMF) and the Woman & Infants Hospital of Rhode Island (WIHRI) were assessed in the whole dataset and in sonographer-specific distributions. Further prospective statistic process control (SPC) methods were applied (Shewhart x and s charts, exponentially weighted moving average (EWMA) and cumulative sum (CUSUM) charts).
Results: Three thousand five hundred and seventy eight NT measurements obtained by seven sonographers were eligible for designed analysis. In the assessment of the sonographer-specific NT distributions three of them did not meet due to the underestimation the FMF and one the WIHRI criteria. Using SPC methods, three sonographers presented unsatisfactory performance with underestimation, three sonographers overall satisfactory performance with transient periods of over- and underestimation and one sonographer showed perfect performance.
Conclusions: Assessed SPC methods showed close agreement with the retrospective ones, but with the advantage that they can be applied prospectively allowing the prompt action in case of malperformace. The EWMA and CUSUM methods were regarded as the most suitable