Bleeding Time (MLT 303) Fall 2023 PDF

Hematology Techniques MLT 303 Normal platelets Dr Amany Abouella fall 2023  Blood platelets Platelets are pieces of very large cells in the bone marrow called megakaryocytes. They help form blood clots to slow or stop...

Hematology Techniques MLT 303 Normal platelets Dr Amany Abouella fall 2023  Blood platelets Platelets are pieces of very large cells in the bone marrow called megakaryocytes. They help form blood clots to slow or stop bleeding and to help wounds heal.  Function of platelets ❖ There are three main stages in the formation of a blood clot: ❑ adhesion ❑ activation ❑ aggregation. ❖play important role in hemostasis: ❑ Maintenance of vascular integrity by sealing defects in vascular endothelium. ❑ Initial arrest of bleeding by forming a plt plug (adhesion aggregation). ❑ Stabilisation of the plug by sharing in coagulation forming fibrin.  Steps of hemostasis BT test BT test PT/ PTT Bleeding time test (BT) Prepared by TA.Nohair Hesham  OUTLINES 1-Introduction 2-Principle of test 3-Methods of bleeding time test 4-Material Required 5- procedures 6- interpretation  1- Introduction Of Bleeding Time Test ❖Bleeding time test is a medical test used to evaluate the ability of blood to form a clot. ❖It measures the time it takes for bleeding to stop after a small incision is made on the skin’s surface. ❖The bleeding time test assesses the function of platelets, which are blood cells responsible for clotting. ❖ It helps diagnosis certain bleeding disorders.  2-Principle of test ❖The duration of bleeding from a standard puncture wound of the skin is a measure of the function of platelets as well as the integrity of the capillary. ❑It is a thorough test of platelets action in vivo. ❑The bleeding time test will depend on : 1- the number of platelets. 2- platelets function. 3-integrity of blood vessels wall 4-the efficiency of tissue fluid in accelerating the coagulation process.  3-Methods of bleeding time test Ivys’s Method Duke’s Method  Ivys’s Method  4-Materials requirement 1- sphygmomanometer ( 40mmHg to maintain constant pressure of the capillaries) 2- alcohol swab 3-automated lancet (Standard incision in depth and length( 4- filter paper 5- stopwatch  5-Procedures of forearm ivy’s method Clean the inner aspect of the forearm with spirit and let dry. Place a blood pressure cuff on the upper arm, inflate at 40 mm Hg, and maintain the same throughout the test. Select an area on the forearm—Volar aspect which is devoid of superficial veins. By using automated lancet to incision two or three punctures 3mm deep are made. Stopwatch is started as soon as the bleeding starts in each wound. Using the edge of a piece of a filter paper to collect the blood, gently touch paper to the drop of blood, which forms over the wound every 30 seconds. The bleeding time is reported when no blood stain is seen on the filter paper after a gentle touch. One can measure both wounds and average them or take the reading of the last one to stop bleeding.  Normal range : (3 - 7 min).  Duke’s method  4-Materials requirement 1- alcohol swab 2-disposable lancet 3- filter paper 4- stopwatch  5-Procedures of duke’s method Clean the fingertip {middle finger} of the patient with alcohol swab and allow the skin to dry completely. Make a deep puncture with the help of a sterile lancet (blood should flow freely without squeezing). Immediately start the stopwatch. Blot the drop of blood coming out of the incision every 30sec by using filter paper. Stop the stopwatch as soon as bleeding ceases.  Normal range : the normal range is up to 6 minutes.  6- INTERPRETATION ❖Bleeding time is prolonged : Thrombocytopenia Platelet dysfunction syndromes Decrease or abnormality in plasma factors such as von Willebrand’s factor Abnormalities in walls of the small blood vessels— vascular defects DIC disease.