A score-based method for quality control of fetal images at routine second-trimester ultrasound examination

Our aim was to develop and evaluate the feasibility and reproducibility of score-based quality control for routine standardized fetal ultrasound images obtained in the second trimester of pregnancy.

In France, a minimum of three biometrical and six anatomical standardized ultrasound planes are to be produced with any mid-trimester scan. All anatomical standardized ultrasound images, routinely obtained by one trained operator at 20 to 24 weeks, were stored prospectively during a 1-year period. Twenty-five examinations containing these images were later randomly selected. These were then analyzed by two reviewers, according to predefined criteria agreed upon on the basis of established standards. This yielded a total score of up to 32 points. Feasibility, inter- and intra-reviewer reproducibility were analyzed.

Routine second-trimester ultrasound examinations numbering 1160 performed over a one year period by one trained sonographer unaware of the subsequent study at the time the images were recorded and stored in a database. Among the 150 images randomly selected and analyzed, adjusted kappa values were above 0.8 for 27 (84%) and 30 (94%) criteria, intra-class correlation coefficient was 0.86 (0.75; 0.96) and 0.98 (0.94; 1) and the mean difference (95% CI) in score was - 0.44 (-3.0; 2.1) and - 0.2(-2; 1.6) for inter- and intra-reviewer comparisons respectively.

A quality control policy based on image scoring is feasible and allows for good inter- and intra-reviewer reproducibility. Besides its potential for audit and quality control, this could also be useful during the training process.