Understanding haemostasis

The normal haemostatic process relies on the presence of normal vascular endothelium, a normal number of functioning platelets and appropriate levels of the coagulation proteins involved in both the propagation and the limitation of clot formation. Our ability to detect abnormalities in the haemostatic process relies initially on taking a thorough bleeding history and on coagulation screening tests. It is vital to understand the limitations of these screening tests and when it is appropriate to perform further investigations and when to seek advice from a haematologist. This review outlines the haemostatic process, and discusses the relevance of abnormal coagulation screen results, the indications for diagnostic coagulation tests,and the pitfalls of bleeding disorders that are not reflected by coagulation screens.