Objective: Our goal was to conduct the generation and piloting of a discriminative and evaluative tool for pediatric post-thrombotic syndrome.Methods: We followed a formative model for the development of the tool, focusing on the signs/symptoms (items) that define post-thrombotic syndrome. For item generation, pediatric thrombosis experts and diagnosed with extremity post-thrombotic syndrome during childhood nominated items. In the piloting phase, items were cross-sectionally measured in children with limb deep vein thrombosis to examine the performance of the items.Result: Twenty-three experts and 16 subjects listed 34 items, which were then measured in 140 subjects with previous diagnosis of limb deep vein thrombosis (70 upper extremity and 70 lower extremity). The items with strongest correlation with post-thrombotic syndrome severity and largest area under the curve were pain (in older children), paresthesia, and swollen limb for the upper extremity group, and pain (in older children), tired limb, heaviness, tightness and paresthesia for the lower extremity group.Conclusion: Diagnostic properties and correlation with post-thrombotic syndrome severity of the different signs and symptoms varied according to the assessed venous territory.The information gathered in this study will help experts decide which item should be considered for inclusion in the new tool.