Acquired bleeding disorders.

tial acquired bleeding disorder is common in clinical practice. The most common cause is anticoagulant therapy, including antiplatelet drugs. With increasing use of pharmacological thromboprophylaxis in both medical and surgical inpatients and increasing indications for long-term antithrombotic therapy, it is imperative to consider drug-induced bleeding during the initial evaluation of abnormal bleeding. Some patients who bleed abnormally during or after surgery have a mild underlying heritable haemostatic defect; an important aspect of assessment is therefore to determine whether there is a heritable defect with late clinical onset. Most congenital disorders of haemostasis are mild (eg von Willebrand disease) and abnormal bleeding may not become manifest until there is a haemostatic challenge such as surgery or menstruation. Effective treatment depends on a critical assessment of the extent and nature of bleeding. Presentation of an acquired bleeding disorder varies between acute unexpected bleeding during or immediately after surgery1 to unusual or excessive bruising, purpura, epistaxis or gum bleeding developing over several months. In all cases a comprehensive history is needed to assess the nature and extent of the bleeding, to guide the clinical examination and determine the most appropriate use of investigations. The major issues to be determined are: • Is haemostatic capacity reduced or is there a non-haematological cause for bleeding? • If haemostatic capacity is reduced, is it due to a heritable defect with late clinical onset or the result of a newly acquired defect? • If newly acquired, is it due to an anticoagulant drug? • If not due to reduced haemostatic capacity, what are the likely circumstances that led to abnormal bleeding?