This document discusses various laboratory tests used to investigate hemostasis and coagulation disorders. It outlines five primary screening tests, including platelet count, bleeding time, prothrombin time (PT), partial thromboplastin time (PTT), and fibrinogen level. More specific coagulation factor assays and tests of fibrinolysis are also mentioned. Details are provided on procedures for common coagulation tests like PT, PTT, thrombin time (TT) and activated coagulation time (ACT). The document discusses the clinical implications of abnormal results and potential interfering factors for interpretation.

1. Blood studies: Hematology & Coagulation Mrs. Nur Aisyah Aziz Pathology Practical 27.12.2010

2. Test of Hemostasis & Coagulation Bleeding disorder Vascular injury Trauma Coagulopathies

3. Laboratory Investigation of Hemostasis 5 primary screening test to diagnosed suspected coagulation disorders: Platelet count, size and shape Bleeding time – platelet fx. & capillaries wall PTT – ability to clot PT – fx. of second-stage clotting factors (????) Fibrinogen level

4. Laboratory Investigation of Hemostasis Factor assay – definitive coagulation studies of specific clotting factors Fibrinolysis – to address problem with fibrinolytic system Euglobulin clot lysis Factor XIII Fibrin split product The investigations of hypercoagulable status PT PTT Fibrinogen test Antiplatelet factors Anticoagulant factors Fibrinolysis tests

5. 1. BLEEDING TIME Primary phase of hemostasis Best single screening test for platelet screening tests platelet fx disorder & coagulation disorder This test is of value in detecting vascular abnormalities and platelet abN & def. Not recommended for routine presurgical workup Procedure: Ivy Method

6. Thrombin time (TT) Stage III fibrinogen defects can be detected by TT test Detection: DIC, hypofibrinogenemia Useful for monitoring streptokinase therapy Test mechanism: time for plasma to clot when thrombin is added N = clot forms rapidly abN = no clot  presence of stage III def.

7. Partial Thromboplastin Time (PTT); Activated Partial Thrombin Time (APTT) PTT – screens for coagulation disorder Specific detection – Intrinsic thromboplastin system & defect in extrinsic coagulation mechanism pathway APTT – detect def. in intrinsic coagulation system, incubating anticoagulants, monitor heparin therapy

8. Activated Coagulation Time (ACT) To evaluate coagulation status ACT responds linearly to heparin level changes Responds to wider range of [heparin] than does the APTT Bedside procedure – requires only 0.4mL of blood Routinely use during dialysis, coronary artery bypass procedures, arteriograms & percutaneous transluminal coronary arteriography HARD TO STANDARDIZE, NO CONTROLS AVAILABLE = results back-up with APTT

9. Prothrombin Time (Pro Time; PT) Prothrombin – a protein, produced by liver, blood clotting Production – depends on adequate vit. K intake & absorption Clotting process – Prothrombin  THROMBIN ProT reduced in liver ds. Important screening test for coagulation dx. Measures – potential defect in Stage II clotting mechanism (extrinsic system) Used to evaluate disfibrinogenemia, heparin & coumarin effect, liver failure & vit. K def.

10. Others: Coagulant factors (Factor assay) Plasminogen (Plasmin; Fibrinolysin) Fibrinolysis (Euglobulin lysis yime; Diluted whole blood clot lysis) Fibrin Split Products (FSPs); Fibrin Degradation Products (FDPs) D -Dimer Fibrinopeptide A (FPA) Prothrombin Fragment (F1+2) Fibrin monomers (Protamine Sulfate Test; Fibrin Split Products) Fibrinogen Protein C (PC antigen) Protein S Antithrombin III (AT-III; Heparin cofactor activity)

11. Platelet count; Mean platelet volume (MPV) Platelet – Fx: blood clotting, vascular integrity & vasoconstriction, adhesion & aggregation activity Production: BM Life span: 7.5 days 2/3 in circulating blood + 1/3 in spleen MPV – uniformity of platelet size, diff. dx of thrombocytopenia ??? Clinical Implications of platelet count & MPV: abN  &  ??? Interfering factors

12. Lab report ??? test Test Reference range Clinical implications Interfering factor(s) ??? Clinical implication & Interfering factors prolonged vs. shortened TT, APTT & increased PT vs. normal PT