To describe a new ultrasound marker of the Great Saphenous Vein at the groin.

An ultrasound marker of the Great Saphenous Vein was identified as follows: the Great Saphenous Vein was tracked in cross-sectionally starting from the Sapheno Femoral Junction and optimally visualized where it crosses the Adductor Longus muscle, i.e., 3–5 cm below the junction. This marker, corresponding to a very superficial position of Great Saphenous Vein, was named "E Point," where E means easy to find. The search for the E point was performed on 230 limbs of 126 subjects with or without chronic venous insufficiency (training population) and the method was validated in 58 subjects (testing population).

The E point was successfully recorded in 128/144 (89%) pathologic and in 85/86 (99%) healthy limbs. Being free from other structures, at the E point the Great Saphenous Vein was always easily calibrated. In 17 cases, the E point could not be identified due to an hypoplasic Great Saphenous Vein; in such instances, the Anterior Accessory Saphenous Vein was well evident and substituted for the Great Saphenous Vein as the main draining vein at the groin.

The E point identifies the Great Saphenous Vein in healthy and varicose patients. Failure to identify the E point indicates Anterior Accessory Saphenous Vein dominance over a hypoplasic Great Saphenous Vein.