Right medial internal jugular vein: a reversed carotid sheath.

Venous access is often essential in critical care medicine. The internal jugular vein (IJV) often provides reliable blood flow when subjected to cannulation. However, anatomical variations of the IJV have been reported as the cause of unsuccessful and complicated venous cannulation. We report ultrasonographic findings of an extremely rare variant of the right IJV in which this structure was located medial to the common carotid artery in the lower neck. A review of the literature on this topic is presented.