Module 2 Preparation of Blood Smears and Bone Marrow Slides Acknowledgments Ministry of Health Guyana Centers for Disease Control and Prevention CDC Global AIDS Program GAP Guyana Centers for Disease Control and Prevention CDC Atlanta American Society for Clinical Pathology ASCP Learning Objectives After completion of this unit of instruction and lecture the student will be able to 1 2 State the importance of a properly made blood smear Describe the procedure for making blood and bone marrow smears by the slide method Objectives Cont d 3 Describe the effects of the following situations when making blood smears dirty slides don t have to be sterile but free of dirt dust and fingerprints b chipped spreader slides c uneven or excess pressure d holding the spreader slide at a steep angle e holding the spreader slide at a shallow angle Spreader slide make smear after blood is deposited on the other slide place it on at 45 degrees Blood is anticoagulated with EDTA ethylene diamine tetracidic acid a Objective 3 Cont d f g h i j k using a large drop of blood too much blood going to the end of smear using a small drop of blood inadequate specimen pushing the spreader slide slowly pushing the spreader slide rapidly lifting the spreader slide before the blood is completely distributed Laboratory Learning Objectives After completion of this unit of instruction and laboratory experience the student will be able to 1 Make at least two 2 well distributed feather edged blood smears using the slide method Introduction Examining peripheral blood smears is an important procedure performed in the Haematology laboratory It is useful in 1 2 3 4 Providing diagnostic information Providing additional data Guiding the selection and monitoring of therapy Indicating adverse effects of treatment Technique The most common method is the push slide or wedge smear technique Materials Needed 1 2 3 4 5 6 Clean glass microscope slides Well mixed EDTA blood sample Device to make a drop of blood Marking pen or pencil Gloves universal precaution treat every patient the same Waste and sharps disposal containers Procedure 1 Be sure the glass slides selected are free of dust and debris If using an anticoagulated blood sample be sure the specimen is well mixed Then using either a plain capillary tube or other type of blood dropping device place a small drop of blood on a glass slide The size of the drop and its position on the slide are important A blood drop about 2 3 mm in size is best The drop should be placed 1 0 cm from the end of the slide opposite from the end that is frosted if that type of slide is provided and in the middle of the slide If don t treat specimen in the proper amount of time it dehydrated 2 Procedure Cont d 3 Rest the slide containing the drop of blood on the fingers of one hand such that a small angle with a table or bench top is formed The slide should lay with its narrow side or width edge on your fingers and the end with the blood drop on the table 4 Grasp a second slide the spreader slide between the thumb and forefinger of the other hand Position the spreader slide on the first slide so that the spreader slide is in front of the blood drop or on the side towards the long end of the first slide The spreader slide should be at about a 25 30 degree angle to the first slide Procedure Continued 5 Pull the spreader slide back into the drop of blood Allow the blood to spread evenly across the width of the spreader slide 6 Maintaining the spreader slide at a 25 30 degree angle push the spreader slide forward in a smooth rapid motion Do not apply any additional pressure As the movement of the spreader slide approaches the end of the stationary slide ease up and off such that the spreader slide trails away from the stationary slide The movement of the spreader slide off the stationary slide should be in one continuous subtle gesture it should not be an abrupt ending This is by far the most difficult step and the one that will require the greatest practice and patience Procedure Continued 7 Label the slide with the appropriate patient information Some slides have frosted ends which makes it easier to record this information 8 Allow the smears to air dry Do not blow on the smears as this can disrupt cellular morphology and cause the formation of unwanted artifacts like target cells Technique for Making a Wedge Smear Spreader slide First slide 25 30o Front of blood drop Blood drop Acceptable Smears Are Smooth homogeneous and have no vacuoles oil causes vacuoles for example jerks streaks or ridges 1 2 to 3 4 the length of the slide Straight at the feathered edge tapers At least 1 3 inch examination area Free of visible clotting Not too thick Characteristics of an Acceptable Smear Feathered edge Origin of blood drop Smooth homogeneous no clots holes bubbles to length of slide Examine the feathered edge and not the most dense area Wright s stained blood smear Potential Problems In Making a Smear Too much blood Wrong angle Too low and the smear will be too long Too high and the smear will be too short Too much pressure on the push slide The size of the drop of blood is essential Using capillary tubes to dispense the drop of blood works very well Caution Other Potential Problems Dirty slides Delay in spreading blood drop Failure to completely spread blood drop Stopping abruptly before completely spreading the blood drop Pushing the spreader slide too quickly or too slowly Examples of Peripheral Blood Smears Ridges caused by chipped not smooth Uneven caused by jerks Summary Making acceptable blood smears depends on having clean glass slides good technique that creates a smear that is free of ridges and vacuoles is evenly distributed is neither too thick or too thin and neither too long or too short