For example, Ruiz et al reported a substantial decrease in the percentage of patients who required blood transfusion or erythropoietin injections after percutaneous PVL repair from 56% to 5%.55 On the contrary, in another study of 168 patients with PVL, blood transfusion requirements decreased only modestly after percutaneous repair from 34% to 21%.79 These inconsistencies may be related to the variable definitions of hemolysis and the degree of PVL reduction achieved. This evidence concerns the gene EPO and periventricular leukomalacia.