Prenatal Ultrasound Markers of Isolated Total Anomalous Pulmonary Venous Return and a Sequential Approach to Reach Diagnosis.

This article comprehensively reviews the literature concerning prenatal ultrasound findings of isolated total anomalous pulmonary venous return (TAPVR) and the application of specific sonographic markers to differentiate among the TAPVR types. These markers can be categorized as direct and indirect, based on either morphological features or hemodynamic changes in TAPVR. Indirect markers include the ventricular disproportion, an increased distance between the left atrium (LA) and the descending aorta, as well as the dilatation of superior vena cava or coronary sinus for supracardiac or cardiac TAPVR, along with abnormal pulmonary venous spectral Doppler patterns. Direct markers predominantly focus on the absence of a connection between the pulmonary veins and the LA. Some direct markers are specific to certain TAPVR types, such as the vertical vein. Diagnosing isolated TAPVR can pose challenges, but following a sequential approach can improve detection rates and outcomes. In cases with equivocal findings, additional follow-ups are recommended. The sequential approach described in the current article provides a step-wise methodology and sonographic markers for prenatal diagnosis of TAPVR, which can be utilized by fetal-maternal medicine specialists, obstetricians, and radiological technicians to ensure timely interventions.