University:
College
Course:
Medical Laboratory Science
Academic year:

2023
Views:

198

Pages:

1
Author:

Carlo M.

CAPILLARY TUBE (DALE AND LAIDLAW’S METHOD) HEMATOLOGY LABORATORY COAGULATION TIME • OUTLINE • Coagulation Time o Methods o Slide Method or Drop o Dale and Laidlaw’s Method o Lee and White’s Method LABORATORY EVALUATION OF SECONDARY HEMOSTASIS: COAGULATION TIME • • • • In secondary hemostasis or blood coagulation, the intrinsic pathway together with the extrinsic pathway helps to activate the common pathway which will lead to the formation of a stable fibrin clot in vivo, upon action of Factor XIII. The evaluation of the factors involved in the intrinsic and common pathway is important since whether there is deficiency or a higher level than the reference values will have a clinical implication. Coagulation or clotting time of blood tests the composite action of all plasma factors acting simultaneously. The time required for the blood to clot is a function of the combined factors inhibiting coagulation on one hand as opposed to the combined factors promoting coagulation on the other hand. Coagulation time is a measure of the ability of the blood to clot and is not influenced by the platelet function besides PF3. The test measures only the required for the formation of the first traces of thrombin sufficient to produce a visible clot. METHODS • • Capillary Blood Methods o Slide Method or Drop o Capillary Tube ( Dale and Laidlaw’s Method) Venous Blood Method o Lee and White method SLIDE METHOD OR DROP • • Material: Cotton, 70% alcohol, Slide (glass) and Stopwatch Procedure 1. Sterilize the finger of the ear lobe with cotton moistened with 70% alcohol. Allow it to dry. 2. Make a puncture to a depth of 3mm. Start the stopwatch as soon as blood appears. Wipe off the first drop of blood with dry cotton. 3. Place a large drop of blood on a clean dry glass slide. 4. After 3 minutes, draw a fine wire or pin through the drop of blood and gently lift the wire or pin. 5. Repeat at 30 second intervals until tiny strands of fibrin clings to the wire or pin. • Procedure 1. Sterilize the finger or the earlobe with cotton moistened with 70% alcohol. Allow it to dry. 2. Make a puncture to a depth of 3mm. Start the stopwatch as soon as the blood appears. Wipe off the first drop of blood as soon as blood appears. 3. Place the tube filled by capillary action for about 2/3 of its length. 4. Lay the tube on the table. 5. After 2 minutes. Gently break off 1 cm of the filled end. 6. Repeat at 30 second intervals until coagulation has occurred. This is revealed by the presence of strands of fibrin, which span the gap at least 5mm between the broken ends. Reference Range: 2 – 6 minutes LEE AND WHITE METHOD • • • • Procedure 1. After 3 minutes, slowly tilt the first and the second tubes until coagulation has taken place. 2. Test the third tube, record the time when tube 3 can be inverted without disturbing the clot. 3. Time elapsed from the first appearance of blood in the syringe and clot formation in the third tube is the coagulation time. Reference Range: 5- 10 minutes Clinical Significance: o Prolonged coagulation time is observed in haemophilia, occasionally in diseases like obstructive jaundice, anemia, leukemia, hemorrhagic disease of the newborn and onset if severe acute fever.