Intraoperator and interoperator repeatability of manual and semi-automated measurement of increased fetal nuchal translucency according to the operator's experience.

Objective: To compare the intraoperator and interoperator repeatability of manual and semi-automated measurement of increased nuchal translucency (NT) in sonographers with different levels of experience.

Methods: One hundred NT images without measurements were selected from the digital database. Half had NT measurements between 2.5 and 3.5 mm, and half had NT measurements above 3.5 mm. Five operators (two experts, three general gynaecologist) measured fetal NT manually and automatically. Each operator was blinded to any pre-existing measurements. Each image was measured twice by each operator. Intraoperator repeatability was assessed by standard deviation of within sonographer repeated measurement. Interoperator repeatability was assessed as difference towards the gold standard, which was defined as the mean measurement of experts.

Results: The overall standard deviation of the difference between the first and the second manual measurements was 0.14 and 0.10 mm for moderate and severely increased NT. It was 0.10 and 0.08 mm with the semi-automated system. Mean difference between the manual measurement of nonexpert operators and the gold standard was -0.01 mm for moderately increased NT and 0.02 mm for severely increased NT. With the semi-automated measurement, mean bias was similar.

Conclusion: The automated NT measurement leads to a further standardization of the NT assessment process. Especially inexperienced operators may benefit from this tool.