* age \< 18 and \> 80 yrs * history of bleeding (peptic ulcer, esophageal varices, cerebral aneurysm, cancer at high risk of bleeding, cirrhosis, hemorrhagic stroke \< 1 year) * thrombocytopenia (\<100 x109/l) * anemia (hb \< 8 g/dl) * coagulation abnormalities (pt e/o aptt \> 1.5; fibrinogen \< 150 mg/dl) * consumption coagulopathy (isth criteria) \[15, 16\] * deep vein thrombosis or pulmonary embolism * dual antiplatelet therapy * ongoing anticoagulant therapy * allergic reaction to lmwh * previous heparin-induced thrombocytopenia * major surgery \< 1 month; neurosurgery \<3 months; eye surgery \<3 months * pregnancy * arterial hypertension (sbps\>160 mm hg; dbp\>100 mm hg) * renal failure (creatinine clearance 30 ml/min) * icu admission or endotracheal intubation

* age \< 18 and \> 80 yrs * history of bleeding (peptic ulcer, esophageal varices, cerebral aneurysm, cancer at high risk of bleeding, cirrhosis, hemorrhagic stroke \< 1 year) * thrombocytopenia (\<100 x109/l) * anemia (hb \< 8 g/dl) * coagulation abnormalities (pt e/o aptt \> 1.5; fibrinogen \< 150 mg/dl) * consumption coagulopathy (isth criteria) \[15, 16\] * deep vein thrombosis or pulmonary embolism * dual antiplatelet therapy * ongoing anticoagulant therapy * allergic reaction to lmwh * previous heparin-induced thrombocytopenia * major surgery \< 1 month; neurosurgery \<3 months; eye surgery \<3 months * pregnancy * arterial hypertension (sbps\>160 mm hg; dbp\>100 mm hg) * renal failure (creatinine clearance 30 ml/min) * icu admission or endotracheal intubation

- age < 18 and > 80 yrs - history of bleeding (peptic ulcer, esophageal varices, cerebral aneurysm, cancer at high risk of bleeding, cirrhosis, hemorrhagic stroke < 1 year) - thrombocytopenia (<100 x109/l) - anemia (hb < 8 g/dl) - coagulation abnormalities (pt e/o aptt > 1.5; fibrinogen < 150 mg/dl) - consumption coagulopathy (isth criteria) [15, 16] - deep vein thrombosis or pulmonary embolism - dual antiplatelet therapy - ongoing anticoagulant therapy - allergic reaction to lmwh - previous heparin-induced thrombocytopenia - major surgery < 1 month; neurosurgery <3 months; eye surgery <3 months - pregnancy - arterial hypertension (sbps>160 mm hg; dbp>100 mm hg) - renal failure (creatinine clearance 30 ml/min) - icu admission or endotracheal intubation

- age < 18 and > 80 yrs - history of bleeding (peptic ulcer, esophageal varices, cerebral aneurysm, cancer at high risk of bleeding, cirrhosis, hemorrhagic stroke < 1 year) - thrombocytopenia (<100 x109/l) - anemia (hb < 8 g/dl) - coagulation abnormalities (pt e/o aptt > 1.5; fibrinogen < 150 mg/dl) - consumption coagulopathy (isth criteria) [15, 16] - deep vein thrombosis or pulmonary embolism - dual antiplatelet therapy - ongoing anticoagulant therapy - allergic reaction to lmwh - previous heparin-induced thrombocytopenia - major surgery < 1 month; neurosurgery <3 months; eye surgery <3 months - pregnancy - arterial hypertension (sbps>160 mm hg; dbp>100 mm hg) - renal failure (creatinine clearance 30 ml/min) - icu admission or endotracheal intubation