Abstract: Objective To investigate the experimental and clinical characteristics of the lupus anticoagulant （LA） positive patients. Methods LA were measured by modified dilution viper venom time assay（DRVVT）,LA normalized ratio greater than 1.2 was identified LA positive. Laboratory indexes and clinical features were observed in LA positive patients. LA negative patients were enrolled as controls. Results LA positive group 51 cases,LA normalized ratio were 1.4±0.4,activated partial thromboplastin time（APTT） were （65+16） second. 31% （16/51）of positive individuals had autoimmune disease. 18% （9/51） of patients with thrombotic events. Bleeding in 3 cases （3/51,6%）,transfusion of blood products in 5 cases. Total of 15 cases had undergone emergency surgery and interventional procedures and without abnormal intraoperative and postoperative bleeding happen. The incidence of thrombus events was higher in LA positive group than in LA negative group （P<0.05）,and no significantly difference was found between incidences of two groups’ bleeding （P>0.05）. Conclusion In LA positive patients, APTT results are significantly prolonged and the risks of thrombosis are high, while the risks of bleeding which including emergency surgery and interventional procedures are not significantly elevated.

Key words: Lupus anticoagulants, Thrombosis, Bleeding