Value of azygos vein / descending aorta ratio in normal fetuses and fetuses with venous malformation related to azygos vein

Objective To evaluate the azygos vein/descending aorta (AzV/DAo) ratio in prenatal ultrasound diagnosis of venous malformation related to AzV. Methods A total of 452 normal fetuses and 25 fetuses with venous malformation related to AzV were included in this study. The AzV and DAo dimensions were measured in 4-chamber view. The AzV/DAo ratio was calculated.Three parameters were compared between normal fetuses and fetuses with venous malformation related to AZV. Results The AzV diameter and AzV/DAo ratio of the study group were significantly greater than those of the normal group (P<0.001). In the study group, 96% (24/25) AzV diameter and 100% (25/25) AzV/DAo ratio were out of 95% normal reference range. Conclusions Abnormal AzV/DAo ratio would be the marker for prenatal screening of venous malformation related to AZV. Key words: Ultrasonography; Fetus; Azygos vein; Descending aorta; Venous malformation