The Value of the Vertical Vein Stenosis Site, Proximal Flow Velocity, and Their Ratio in Prenatal Ultrasound Diagnosis and Prognostic Assessment of Fetal TAPVC With PVO

Objective To evaluate the potential value of peak velocity at the vertical vein obstruction site ( V max ), proximal vertical vein velocity ( V p ), and their ratio ( V max / V p ) in the prenatal diagnosis of fetal total anomalous pulmonary venous connection (TAPVC) with pulmonary venous obstruction (PVO) and in early neonatal risk assessment. Methods This was a retrospective cohort study. A total of 8 fetuses with TAPVC and PVO (14 examinations), 6 fetuses with TAPVC without PVO (11 examinations), and 50 normal fetuses were enrolled. Peak velocities of the vertical vein (or pulmonary vein) were compared across the three groups. In the PVO group, the correlations between indicators such as V max , V min , V mean , PVVI, V p , and V max / V p and clinical outcomes (including neonatal acidosis, hypoxemia, severity of pulmonary hypertension, and death) were analyzed. Results V max was higher in the PVO group than in the TAPVC without PVO and normal groups ( p < 0.001). V p was lower in the PVO group than the corresponding pulmonary venous velocity in normal fetuses ( p < 0.001). V max was not significantly correlated with V max / V p (rs = 0.43, p = 0.126), suggesting that the ratio may provide additional hemodynamic information beyond V max alone. Lower V p was associated with acidosis, hypoxemia, more severe pulmonary hypertension, more severe obstruction, and mortality (all p ≤ 0.03). V max / V p was associated with the severity of pulmonary hypertension ( p = 0.045). Conclusion In this small exploratory cohort, V p and V max / V p appeared to provide complementary information to V max in fetuses with TAPVC and PVO. These preliminary findings suggest that combined assessment of proximal and stenotic‐site velocities may help identify atypical obstruction and support prenatal risk stratification.