A Case of Double Superior Vena Cava with a Rare Accessory Hemiazygos Arch Crossing over the Descending Aorta in a Male Body Donor

While performing a routine anatomical dissection on a male donor, undergraduate medical students observed an uncommon vascular anomaly: a persistent left superior vena cava (LSVC). Prior to the anatomical dissection, computed tomography (CT) images were obtained in an embalmed condition. Relevant anatomical structures were measured using the JiveX DICOM Viewer. The left brachiocephalic vein (LBV) was present as a communicating vessel with a markedly reduced diameter between the LSVC and the right superior vena cava (RSVC). The diameters of RSVC and LSVC averaged 19.4 mm and 15.2 mm, respectively. The LSVC drained into a dilated coronary sinus (CS), which measured 22.7 mm in diameter. In addition, the left accessory hemiazygos vein collected the 2nd to 5th left intercostal veins, forming a small-caliber venous arch (2.1 mm in diameter) at the T5 vertebral level, which crossed anterior to the thoracic aorta, before draining into the LSVC. In comparison, the azygos venous arch on the right side is connected to the RSVC at T4. Knowledge of such venous variations through preoperative imaging—such as CT, MRI, or echocardiography—can be essential for procedural planning and for minimizing inadvertent complications. This case also highlights a dual approach, combining anatomical dissection with detailed CT analysis of the same specimen, which can both enhance undergraduate anatomical education and contribute to high-quality morphological research.