Coagulation testing: what to do and how to do it

Abstract

Background: Coagulation, or clotting, is the process of blood changing from a liquid to a solid form. Haemostasis is the stopping of blood flow, which occurs naturally to prevent blood loss after vascular injury. This happens through formation of a stable thrombus; however, it is also important that clotting is not excessive. To ensure a stable thrombus, prevent thrombosis or premature clot breakdown, a functioning balance between coagulation, anti‐coagulation and fibrinolysis is required; this process involves complex interactions between blood vessels, platelets, coagulation factors, various proteins and the fibrinolytic pathway. Imbalance in these pathways may result in spontaneous haemorrhage, uncontrolled trauma‐induced haemorrhage, delayed bleeding or thrombosis. Aim of the article: This article reviews the haemostatic process, discusses the cascade and cell‐based models and emphasises the role inflammation can play in thrombin production in the absence of trauma. It outlines the commonly available coagulation tests, discusses their limitations and how to best use these tests to investigate well‐recognised haemostatic disorders.