SummaryPerioperative bleeding complications due to disorders of primary haemostasis are often underestimated. Routine determination of primary haemostasis is still problematic. The in vivo bleeding time (BT) shows low sensitivity and high variability. In this contribution the results and experiences with the IVBT having been obtained in various studies and during 10 years of routine use are reported. Patients and Methods: Blood donors before and after ASA ingestion, patients with thrombocytopenia as well as congenital and acquired platelet function disorders. Monitoring of desmopressin efficacy. IVBT with Thrombostat 4000 (tests with CaCl2 = TST-CaCl2 and ADP = TST-ADP) and PFA-100 (test cartridges with epinephrine = PFA-EPI and ADP = PFA-ADP). Results and Conclusions: IVBT becomes abnormal with platelet counts <100,000/μl. With platelet counts <50,000/μl the results are mostly outside the methodical range. IVBT proved clearly superior to BT in von Willebrand syndrome (vWS). All 16 patients with vWS were detected by PFA-EPI, whereas with BT 7 of 10 patients with moderate and 1 of 6 patients with mild forms of vWS were spotted. The majority of acquired and congenital platelet function disorders with relevant bleeding tendency were detectable by IVBT. Sometimes diagnostic problems arose in case of storage pool defect. Four to 12 h after ingestion of a single dose of 100 mg ASA the TST-CaCl2 became abnormal in all cases, the PFA-EPI only in 80%. However, the ASA sensitivity of TST-CaCl2 proved even too high when looking for perioperative bleeding complications in an urological study. Therefore, the lower ASS sensitivity of the PFA-100 seems to be rather advantageous for the estimation of a real bleeding risk. The good efficacy of desmopressin in the majority of cases with mild thrombocytopenia, congenital and acquired platelet function disorders and even ASS-induced platelet dysfunction could be proven by means of the IVBT. Thus IVBT may help to increase the reliability of the therapy. However, the IVBT with the PFA-100 is not yet fully developed. Nevertheless, routine use can be recommended when special methodical guidelines are followed.
