Acquired disorders of coagulation

Normal coagulation is a delicate balance between pro- and antithrombotic mechanisms. Haemorrhage results from dysfunctional/absent procoagulant mechanisms and can be caused by inherited or acquired factors. The most common acquired abnormalities seen in clinical settings are covered in this article, including vitamin K deficiency, warfarin therapy, liver disease, direct oral anticoagulants, disseminated intravascular coagulation, platelet disorders and vascular disorders. Patients with new-onset abnormal bruising or bleeding require a full history and examination to allow targeted investigations. Most interventions target the underlying cause but other specific measures such as reversal of warfarin, vitamin K replacement, clotting factor replacement or blood product transfusion can be required. Liver disease results in complex haemostatic changes, and the management of bleeding depends on its site and severity. Disseminated intravascular coagulation can complicate many clinical situations and needs prompt action when patients are bleeding. Acquired dysfunction of platelets is commonly encountered in clinical practice, often in association with drug therapy (e.g. aspirin), but also with more widespread medical conditions such as renal failure or after procedures such as cardiopulmonary bypass.