In this study, the authors present an analysis of the outcomes of 105 low-flow vascular malformation patients treated over a 6-year period and report specific lesion characteristics that correlate with those vascular malformations that will benefit from sodium tetradecyl sulfate foam sclerotherapy (STS FS) versus surgical resection as well as morphological characteristics of vascular malformations that are associated with a poor response to FS treatment. Improvement in symptoms was documented in 92.9% of patients treated with STS FS. There were no complications. Low-flow vascular malformations that were morphologically characterized by microcystic, septated vessels did not respond to FS, and these vascular malformations are best treated with surgical resection. Primary surgical resection is also the treatment of choice for localized, microcystic, and superficial low-flow vascular malformations. Symptomatic, diffuse, extensive, macrocystic malformations that involve multiple tissue planes and vital structures are best treated with FS.