Background: venous thromboembolism (VTE) is a common complication in critically ill patients, admitted to the Intensive Care Units (ICUs). At the present time, there is no validated score to estimate risks and benefits of antithrombotic pharmacological prophylaxis in this subset of patients. Results of a pilot study showed that ultrasound (US) screening for deep vein thrombosis (DVT) is associated with a reduced incidence of proximal DVT, up front to an overall increased discovery rate of DVTs. The reduced incidence of proximal DVT could be attributed to an early diagnosis of distal and muscular DVTs, which would eventually receive a more adequate management. Proximal DVTs are associated with a worse long-term prognosis than distal or muscular DVTs, so it can be hypothesized that the active US screening could lead to an improvement of in-hospital and long-term prognosis of patients admitted to the ICU. Aim of the study: to test whether an active US screening may reduce the incidence of proximal DVT and improve the in-hospital and long-term prognosis of patients admitted to the ICU. Expected relevance: systematic screening for DVT could improve the management of the pharmacological antithrombotic treatment, leading to a reduction of thromboembolic and bleeding complications. This will eventually lead to an improved in-hospital and long-term prognosis.