Ultrasound-Based Z Score and Pulmonary Valve/Aortic Valve Diameter Ratio Improving the Predictive Value of Fetal Aortic Stenosis.

Objective: This study aims to investigate the predictive value of the ultrasound-based Z score for the aortic valve (AV) diameter, pulmonary valve (PV) Z score, and the PV/AV ratio in diagnosing aortic stenosis (AS) in fetuses.

Methods: A prospective study of 24 singleton fetuses with suspected AS who underwent two or more fetal echocardiograms was enrolled. Based on the pregnancy outcomes, the prenatal cases were divided into two groups: the AS group and the false-positive group. Electronic spatiotemporal image correlation (eSTIC) technology was used to measure AV and PV of all fetuses, and the AV and PV Z scores, along with the PV/AV ratio, were calculated, compared, and analyzed.

Results: In the AS group, significant differences were found between the first and second echocardiograms regarding the AV Z score, PV Z score, and PV/AV ratio. In the false-positive group, only the PV Z score and PV/AV ratio showed significant differences. In the first echocardiogram, the AV Z score and PV/AV ratio significantly differed between the AS and false-positive groups. In the second echocardiogram, only the AV Z score showed differences. An AV Z score < -2.46 showed high sensitivity (89.5%) and specificity (100%) for AS diagnosis. When combined with a PV/AV ratio > 1.64, the predictive value increased.

Conclusion: Fetal echocardiography with an AV Z score <-2.46 and a PV/AV ratio > 1.64 provides a higher predictive value for diagnosing AS in fetuses.