Proposed mechanisms of thrombosis in IBD. IBD predisposes to thrombosis by inducing episodes of acute and chronic intestinal inflammation, leading to a systemic prothrombotic state characterized by upregulation of tissue factor, an elevated platelet count, and impaired fibrinolysis as a result of decreased expression of tissue plasminogen activator (t-PA) and decreased expression of plasminogen activator inhibitor-1 (PAI-1). Clinical risk factors, such as dehydration, malnutrition, and placement of central venous catheters also contribute to thrombotic risk in patients with IBD.