Hematology Lab - 12 Bleeding Time

MODIFIED IVY’S METHOD HEMATOLOGY LABORATORY BLEEDING TIME • OUTLINE • Bleeding Time o Materials and Methods o Duke’s Method o Modified Ivy’s Method o Copley-Lalitch Method o Clinical Significance • • LABORATORY EVALUATION OF PRIMARY HEMOSTASIS: BLEEDING TIME • • Primary hemostasis is the first response of the body following blood vessel injury. The platelets and the vascular responses are the main players in their stage to prevent undue loss of blood. There are three stages involved in primary hemostasis and these are: platelet adhesion, platelet activation and platelet aggregation which result in the formation of platelet/hemostatic plug. Bleeding time is the interval required for the blood to stop flowing from a skin incision. Bleeding time does not necessarily parallel the coagulation time of the blood. It measures the ability of blood vessels to control bleeding injury by formation of platelet plug or hemostatic plug. It tests the function of platelets as well. • COPLEY- LALITCH METHOD • MATERIALS AND METHODS • • Materials o 70% isopropyl alcohol o Cotton o Blood lancet o Filter Paper o Timer Methods: o Duke’s Method o Modified Ivy’s Method o Copley- Lalitch Method DUKE’S METHOD • • • Principle o The Lobe of the ear is the site of choice for puncture. It should be warmed before the test or before incision is made. Then take bleeding time. Procedure 1. Clean the site for puncture (finger or lobe of the ear) with cotton moistened with alcohol. Allow it to dry. 2. Puncture the lower edge of the ear lobe to a depth of 3mm. Wipe off the first drop with a dry cotton and start the stopwatch as soon as blood appears. 3. At half minute intervals, apply gently to the drop of blood, taking care not to touch the skin. End point is reached when no more blood is absorbed by the filter paper. Reference Range o 2-4 minutes (however, normal persons may occasionally give up values up to 5 minutes) Principle o Capillary pressure is standardized and the average of bleeding time from three separate incisions in the forearm is noted. This provides a very accurate technique if the incisions are identical. Procedure 1. A sphygomomanometer cuff is placed around the patient’s upper arm. The pressure is raised to 40mmHg and maintained at this level for the duration of the test. 2. Sterilize the site of puncture. Using a sterile lancet, make a puncture wound, 3mm deep along the flexor (inner) aspect of the forearm, avoiding any visible vein or skin lesions. 3. Start the stopwatch. At half minute intervals, gently blot the blood with filter paper until no more blood appears on the filter paper, taking care not to touch the skin. Note the time. 4. The blood pressure cuff is decompressed. 5. Repeat the test (the above procedure) at 5 minute intervals until there are 3 recordings of bleeding time. 6. Take the average of the 3 bleeding times. Reference Range: ½ - 7 minutes • Procedure 1. Sterilize the finger tip with 70% alcohol and allow it to dry. 2. Make a puncture to a depth of 6mm. start timing. 3. Immerse the puncture finger in sterile physiologic saline solution warmed at 37oc until the bleeding stops. 4. Record the bleeding time. Reference Range: >3 minutes CLINICAL SIGNIFICANCE • Prolonged bleeding time is seen: o When the blood platelets are greatly reduced o Thrombocytopenic purpura o Acute Leukemia o Aplastic anemia o In injury to capillary wall o Scurvy o Toxins (infection, chemical, snake venom) o Allergy o In prothrombin deficiency o Destructive disease of the liver with hemorrhagic tendencies o Haemolytic disease of the newborn o Slightly prolonged in severe anemia