•Scurvy, Cushing syndrome and Ehlers-Danlos syndrome are associated with microvascular bleeding resulting from impaired formation of collagens needed for support of vessel walls

Tests used to evaluate different aspects of hemostasis are the following: •Bleeding time: This measures the time taken for a standardized skin puncture to stop bleeding and provides an in vivo assessment of platelet response to limited vascular injury. The reference range depends on the actual method employed and varies from 2 to 9 minutes. Prolongation generally indicates a defect in platelet numbers or function. •Platelet counts: These are obtained on anticoagulated blood using an electronic particle counter. The reference range is 150 to 400 × 10 3 /μL. •Prothrombin time (PT): This assay tests the extrinsic and common coagulation pathways. A prolonged PT can result from deficiency or dysfunction of: factor VII, factors X, V, prothrombin, or fibrinogen. •Partial thromboplastin time (PTT): This assay tests the intrinsic and common clotting pathways. Prolongation of the PTT can be due to deficiency or dysfunction of: factors VIII, IX, XI, or XII, factors X, V, prothrombin, or fibrinogen.