 First, while decreases in coagulation factor levels may increase the risk of bleeding, this only occurs when coagulation factor levels decrease below a minimum hemostatic threshold. The minimum hemostatic for most coagulation factors is 30. In vitro data demonstrates that, in samples with a single factor coagulation deficiency, the commonly used coagulation tests, the prothrombin time usually reported as an international normalized ratio INR and the activated partial thromboplastin time aPTT will become abnormal when the levels are 25-40 or below. However, in the setting of multiple factor deficiencies, which is the situation usually encountered in clinical practice, mild to moderate increases in INR are seen with coagulation factor levels that are considerably higher than the minimum hemostatic threshold of 30. Work by the group and others confirm that in patients with critical illness and liver disease factor levels are consistently above the hemostatic threshold even when the INR is elevated. This lack of correlation between abnormal coagulation test results and increased bleeding risk is supported by a systematic review of observational studies that showed no increased bleeding risk in patients with abnormal coagulation tests as compared to patients with normal coagulation tests. 