ANALYSIS OF PATIENTS WITH A PROLONGED BLEEDING TIME

Abstract

The bleeding time (BT) is one of the most important screening tests in patients with a bleeding tendency. Investigations of Von Willebrand Factor and aggregation tests form routine diagnostic tools to analyse a prolonged BT. In many patients, however, this approach fails to explain the bleeding tendency because no abnormality is found. In order to deal with this problem , we chose three methods: I) determination of platelet nucleotides and serotonin in all patients with a prolonged BT, independent of the results of aggregation tests, II) measurement of platelet adherence to purified collagen and the matrix of endothelial cells in a perfusion system, III) measurement of adherence of normal blood to matrix of patients' fibroblasts. I) In a group of 145 patients with a prolonged BT and a normal platelet count the diagnosis von Willebrand1's disease was made in 52 patients (36%), congenital Storage Pool Disease (SPD) in 27 pts (18%), defect of thromboxane synthesis in 4 pts (3%) and platelet function disorders with miscellaneous aggregation abnormalities in 23 pts (16%). No abnormalities were found in 39 pts (27%). Analysis of aggregation tests, disclosed normal aggregation tracings in many patients with SPD: 23% of 106 patients with congenital or acquired SPD had normal aggregation tests.Adhesion studies were performed with the blood of 7 patients with an unexplained prolonged bleeding time. Two patients had a severe defect and one patient a mild defect of adherence. Further studies revealed the presence of an autoantibody on the platelets in one of these patients.In order to diagnose vessel wall defects which may cause a prolonged BT, we studied the adherence of normal blood to the matrix of the fibroblasts of one patient. We found a decreased adherence, which suggests the presence of a vessel wall defect causing a prolonged BT.We conclude that in many patients with a prolonged BT and normal VWF parameters and normal aggregation tests, SPD or adhesion defects may be responsible for a bleeding tendency.