A rare case of bilateral absence of the external jugular vein: implications for clinical procedures involving the cervical region.

The external jugular vein has recently gained attention as an alternative access route for intravenous therapies because of its superficial position. However, congenitally anatomical variability in the collateral venous network, including the external jugular vein, is well recognized. During a gross anatomy dissection course, we found a rare case in which both external jugular veins were completely absent in an 81-year-old Japanese male cadaver. On the right, the anterior jugular vein was thick and received the common facial vein, forming a compensatory route for the absent external jugular vein. On the left, the anterior jugular vein was thin, and the major blood flow from the common facial vein drained into the internal jugular vein. On both sides, the anterior jugular veins descended along the medial margin of the sternocleidomastoid muscles and communicated medially, forming a jugular venous arch. This case provides important anatomical insight into rare variations of the external jugular vein, which may aid in the safe and rapid selection of alternative access routes for intravenous therapies.