Practical 3 Clotting-time PDF
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Uploaded by SpeedyBarbizonSchool
Tanta University Faculty of Medicine
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Summary
This document outlines the procedure for determining clotting time, with detailed steps for the slide, capillary tube, and test tube methods. It also covers the definition, principle, normal value, and materials required for each procedure. The document includes factors that may affect clotting time.
Full Transcript
Clotting time (CT) 1-Definition: Clotting time is the time needed for blood to clot after withdrawal from the body (measured from time of start of bleeding till firm clot is formed). Clotting time (CT) 2-Principle: When blood sample is collected in a test tube, clotting occurs in it by intrinsic pat...
Clotting time (CT) 1-Definition: Clotting time is the time needed for blood to clot after withdrawal from the body (measured from time of start of bleeding till firm clot is formed). Clotting time (CT) 2-Principle: When blood sample is collected in a test tube, clotting occurs in it by intrinsic pathway (depending on factors XII, XI, IX & VIII), then common pathway (X, V, Ca+2, II & I) Clotting time (CT) 3-Normal value: 4-8 minutes. Clotting time (CT) 4-Materials: -70% alcohol -Sterile pin or lancet, syringe -Glass slide, capillary tube or test tube. 5-Procedure (steps): 3 methods are available; a-Slide method b-Capillary tube method c-Test tube method Clotting time (CT) a-Slide method -Sterilize the thumb, prick it with sterile pin & record the time at pricking. -Put a drop of blood on the glass slide, after 2-3 minutes, examine the drop for formation of fibrin threads by stirring (moving) it by head of a pin till threads appear & record time of its appearance. -Clotting time is the time from pricking to formation of fibrin threads. Clotting time (CT) b-Capillary tube method: -Sterilize the thumb, prick it with sterile pin & record the time at pricking. -Fill capillary tubes with blood (by putting them perpendicular on oozing blood, blood will rise by capillarity). -After 2-3 minutes, examine for formation of fibrin threads by breaking small piece of capillary tube every 30 seconds, till threads appear between broken ends. -Clotting time is the time from pricking to formation of fibrin threads. Clotting time (CT) c-Test tube method: -Sterilize the skin over a vein & take a venous blood sample by syringe. -Evacuate blood in 2 test tubes & place them in a water path at 37˚C. -Examine for clot formation by tilting one tube every 30 seconds. till the tube can be inverted without spilling of blood (2nd tube is used to confirm CT recorded by 1st tube). - -Clotting time is the time from pricking to formation of fibrin threads. Clotting time (CT) 6-Factors affecting CT: Clotting time is prolonged in: a-Coagulopathies e.g. vitamin deficiency (& chronic liver diseases) and hemophilia b-Patients under anticoagulant treatment: e.g.
