hemostasetest

The term hemostasetest refers to a set of laboratory assays used to evaluate the hemostatic system, which maintains blood fluidity and promotes cessation of bleeding. Hemostasis testing helps identify coagulation factor deficiencies, platelet disorders, and vascular abnormalities; it is used in diagnosing bleeding tendencies, planning surgeries, and monitoring anticoagulant therapy.

Core tests include prothrombin time (PT) with international normalized ratio (INR), activated partial thromboplastin time (aPTT), and thrombin time (TT). Measuring fibrinogen level and specific coagulation factors may be needed for further evaluation. Platelet count is routine; dedicated platelet function tests (eg, PFA-100, ristocetin cofactor) assess platelet performance. Viscoelastic tests such as thromboelastography (TEG) or rotational thromboelastometry (ROTEM) provide a real-time view of clot development and breakdown.

Indications include evaluation of bleeding, abnormal preoperative screening, and monitoring anticoagulation (PT/INR for vitamin K antagonists, aPTT for unfractionated heparin). They are also used to investigate suspected inherited coagulation disorders (eg, hemophilia, von Willebrand disease), liver disease–related coagulopathy, and disseminated intravascular coagulation.

Specimen handling matters. Most tests use citrated plasma, and results are affected by collection, transport, and timing. Reference ranges vary by method and instrument, and single abnormal results require clinical correlation and sometimes repeat testing.

Limitations include that no single test captures overall hemostasis; interpretation should integrate history, physical examination, and multiple assays. Advances include point-of-care viscoelastic testing and genetic studies for inherited conditions.