Prenatal ultrasound findings of the IVC takeoff appearance: Teaching cases highlighting IVC interruption and double vessel sign

Familiarity with the relationship between the aorta and inferior vena cava (IVC) in the fetal upper abdomen and thorax are important for evaluating fetal systemic venous anatomy during prenatal ultrasound. In a routine 18-week fetal scan, the IVC Takeoff Appearance was visualized, supporting normal anatomical alignment of the IVC and aorta. In contrast, a 28-week late anomaly scan demonstrated absence of the IVC Takeoff Appearance in a fetus with dextrocardia, raising suspicion for interrupted IVC with azygos continuation and associated double vessel sign. The IVC Takeoff Appearance can be visualized in sagittal and axial planes using a 5 MHz curvilinear transducer, while color Doppler assists in identification of venous flow patterns. These teaching cases demonstrate how the IVC Takeoff Appearance may serve as a useful educational landmark during prenatal ultrasound evaluation of fetal venous anatomy, supporting targeted assessment and recognition of potential IVC anomalies.