Antenatal Detection of Aberrant Subclavian Artery (ARSA) by 4D-Volume Contrast Imaging and High Definition Flow in Mid-trimester Ultrasound Exam

Purpose: To report a small series of ARSA (Aberrant Right Subclavian Artery) cases which were diagnosed by 4-D (Dimensional) ultrasound (Volume Contrast Imaging-A Plane) with high definition flow technique. Method: Clinical data of total 1859 singleton, low risk pregnancies from the hospital database. Total 13 cases with isolated ARSA cases were identified. Results: Total 13 cases with isolated ARSA cases were identified. Median maternal age was 32 years old. Median gestational age at ultrasound exam was 21 weeks. Eleven of thirteen cases were isolated. Case 3 had a muscular ventricular septal defect (VSD) and case 6 had an aberrant left subclavian artery. All cases were detected by 4D VCI-A with high definition flow technique successfully. One fetus with ARSA who was misdiagnosed as normal by conventional 2-D ultrasound, 4D VCI-A with high definition flow revealed abnormal courses of the right subclavian artery. Course of azygos vein was discriminated from the ARSA in all cases. Conclusion: 4D VCI-A mode activated with HD-flow (High Definition) is a valuable tool for the investigation of outflow tracts of fetal heart and proximal branches of aorta in midtrimester scans and carries some advantages over conventional 2D sonography combined with High Definition Flow mode.