Comparison of platelet glass bead retention techniques in patients with clinical bleeding disorders.

Platelet glass bead retention by the Salzman and infusion pump techniques were compared in 36 control individuals, 10 patients with von Willebrand's syndrome and four patients with thrombocytopathies. No significant differences between the results of the two assays were observed. Eleven percent or less of the control individuals had diminished platelet glass bead retention. The mean percentage platelet retention of the von Willebrand's group and the thrombocytopathy group was less than the mean platelet retention of the control group. However, at least 50 percent of the patients with von Willebrand's syndrome had normal platelet retention by both methods. In the thrombocytopathy group, glass bead retention was more consistently diminished. Although an inverse correlation existed between the duration of bleeding time and the platelet retention assays, consistently diminished platelet retention results were observed only when the bleeding time was 18 minutes or longer. It has been concluded by us that while the glass bead retention assays may be helpful in characterizing certain types of platelet disorders, they are not useful screening assays in the diagnosis of von Willebrand's syndrome.