OBJECTIVE : We propose an image scoring method to improve the quality and the reproducibility of measurement of the AV interval before establishing reference tables of the measurements and studies on the prevention and treatment of first-degree AV block especially if the first child has been diagnosed AV block. METHODS : Prospective study from May 2015 to June 2016. Sonographers were asked to measure AV interval with pulsed Doppler in a five-chamber view in standard second-trimester screening before and after having received our image scoring method. Images were scored by 2 blinded reviewers. RESULTS : The intra-class correlation coefficient (ICC) between the two reviewers for the overall score was 0.91. On average, the measurement quality increased by 2.5 points/10 (95% CI 1.0-4.0). In the second set of images, after the scoring method was given, the score stared at 6.50 for the first image, with a significant improvement of 0.18 (p = 0.016) per subsequent image comparing to a non significant improvement for the first set of image. There was a significant improvement in intra-observer reliability, ICC: 0.680 [95% CI 0.606-0.854] versus 0.458 [95% CI 0.140-0.651]. CONCLUSIONS : The use of this scoring method is simple, reproducible and improves image quality and reproducibility of AV interval measurement in a five-chamber view.