Reliability of posterior-left atrium space index measurements during 20-24 weeks of gestation in structurally normal fetuses.

Objective: We aimed to evaluate the correlation between clinical parameters and the post-left atrium (LA) space index, which is a candidate screening marker for total anomalous pulmonary venous connection (TAPVC). We also calculated the inter- and intra-observer variabilities of measurements for this parameter.

Methods: The LA-descending aorta distance/descending aorta diameter ratios (post-LA space index) were obtained from 165 fetuses between 20 and 24 weeks of gestation. Regression analyses were utilized to evaluate the correlations across clinical parameters and the post-LA space index. Intraclass correlations coefficients were calculated for the intra- and inter-observer agreements of three examiners with different sonographic experience.

Results: The mean (±SD) maternal and gestational age (GA) was 28.6±4.9 years and 21.7±0.9 weeks of gestation, respectively. In multivariate analyses, there was no correlation between post-LA space index and maternal age, fetal gender, or GA at cardiac scan. There were moderate to strong correlations across the measurements by different examiners, indicating good inter- and intra-observer agreements.

Conclusion: The post-LA space index during 20-24 weeks of gestation is a simple and reliable marker that is not affected by GA. However, its potential as a screening tool for TAPVC warrants further clinical investigation.