Quality control of an image-scoring method for nuchal translucency ultrasonography.

OBJECTIVE

The objective of the study was to describe a new image-scoring method (NISM) for the measurement of nuchal translucency and crown-rump length on ultrasound scans and to establish interreviewer reliability.

STUDY DESIGN

This NISM was based on 8 criteria on a scale of 4 levels (1-4) established on clearly defined ultrasound reference marks. Ten reviewers assessed the same images of 30 fetuses. After a short training period, the same images and those of 30 new fetuses were scored by these 10 reviewers.

RESULTS

The differences in scores among the 10 reviewers were significant for 4 of 45 pairwise comparisons before training, but no pairwise comparison was significant after training. Interreviewer variance was significantly lower after training (P = .045). The intraclass correlations before and after training were 0.75 and 0.82. For each criterion, the scores were dichotomized into 2 categories (1-2 vs 3-4). Kappa values for each criterion were substantial (0.61 to 0.80) or even almost perfect (0.81 to 1.00).

CONCLUSION

This NISM was highly reliable for the total scores and for each criterion evaluating the image of nuchal translucency and crown-rump length and provides a relevant quality control tool for ultrasound operators.