The frequency of venous reflux was nearly identical across GSV types. The frequency of segmental aplasia was similar in patients with and without reflux. Despite these similarities, defining GSV type and identifying segmental aplasia can provide guidance for treatment. In particular, type D GSVs, defined by the presence of an anterior accessory branch, should be investigated when performing CDUS. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:332-336, 2017.