c5-PERIPHERAL BLOOD SMEARS.docx

CHAPTER 5 ========= Special Collections =================== OVERVIEW -------- Special collections address a variety of patient needs and conditions. Peripheral blood smears use glass microscope slides to allow close examination of blood components. The standard method for preparing peripheral blo...

CHAPTER 5 ========= Special Collections =================== OVERVIEW -------- Special collections address a variety of patient needs and conditions. Peripheral blood smears use glass microscope slides to allow close examination of blood components. The standard method for preparing peripheral blood smears (blood films) is with the wedge smear (push slide) technique. Be sure to collect blood cultures using strict antiseptic techniques to prevent contamination of specimens, which could result in an inappropriate antibiotic prescription for the patient. For infants, the standard blood collection process for inborn errors of metabolism involves skin puncture procedures performed on the heel. Another type of special collections is blood banks where blood is collected for donation. You might also work with other medical professionals to calculate the effect of frequent venipunctures to ensure that patients- especially infants-are not at risk of developing iatrogenic anemia, which can endanger their health. Collection of nonblood specimens-including urine, saliva, sputum, fecal matter, and semen-are also the responsibility of phlebotomists. At times, you can be required to perform throat or buccal swabs to obtain nonblood specimens. Objectives ---------- Upon completion of this chapter, you should be able to: Prepare peripheral blood smears. Perform blood culture collections. Assist other health care professionals with specimen collection. Collect blood samples for inborn errors of metabolism. Perform phlebotomy for blood donations. Calculate volume requirements in order to avoid causing iatrogenic anemia. Perform nonblood specimen collections. PERIPHERAL BLOOD SMEARS ======================= A blood smear is a thin film of blood spread onto a microscopic glass slide. Blood smears are used to microscopically examine blood. Either venous blood in a tube or capillary blood collected by capillary puncture (also called a dermal puncture) may be used. Blood smears can also be prepared by applying blood directly from a finger onto the slide. It is important to prepare these blood slides properly to ensure accurate diagnoses for patients. Depending on your facility, you might prepare blood smears yourself or assist laboratory personnel in preparing them. If a smear is needed to confirm abnormal findings, it must be prepared within 1 hr. of collection when the specimen is obtained in an EDTA tube. To prepare blood smears, the wedge method is used. This is the touching of two slides at an angle, which forms a wedge shape. Most large laboratories use an automated slide-maker, which creates a perfect thin smear with the push of a button. These are available in fixed and portable versions and produce consistent, high-quality smears that stain well and support high-quality results. Both techniques-automated and by hand-produce thin smears from fresh, anticoagulated drops of blood. Steps to perform a manual slide smear: 1. Wash hands and don gloves. 2. Assemble the equipment needed for the dermal puncture or obtain a tube of uncoagulated blood (usually containing EDTA). 3. Make sure you have at least two clean microscopic glass slides. 4. If performing a dermal puncture a. Perform the finger puncture using a semi-automated lancet device. b. Wipe away the first drop of blood with a piece of gauze. c. Apply pressure to the first finger joint to obtain a free-flowing drop of blood. d. Allow the drop of blood to fall onto the glass slide toward one end. e. If preparing smears using tubes of blood, check the specimen for proper labeling. 5. Use a safety device to access the blood. If no safety device is available, carefully uncap the specimen tube behind a safety shield and use a disposable pipette or plastic dropper to remove some of the blood. You may also use applicator sticks or a capillary tube to place the drop on the slide. 6. Place the slide on a flat work surface and apply a drop of blood onto the slide approximately ½ to 1 inch from the end of the slide. 7. Discard the applicator stick or capillary tube into a sharps container. 8. Pick up the spreader slide with your dominant hand, holding it at a 30° to 35° angle. 9. Place the edge of the spreader slide on the smear slide in front of the drop of blood. 10. Pull or back up the spreader slide toward the frosted end of the slide until the spreader slide touches the blood drop. 11. Let the blood drop spread almost to the edges of the spreader slide. 12. Push the spreader slide toward the clear end of the slide (with one light, smooth, fluid motion) until you come off the end. Maintain the 30° to 35° angle 13. Label with the patient information using a permanent marker or aliquot label. 14. Allow the smear to air dry before staining. Do not blow on it. *Most of the drop of blood should spread out onto the glass slide. It will be thicker at the drop and thinner at the opposite end. If properly made, there will be a critical area used for performing the differential, and a tail with a feathered edge that is slightly rounded. Blood smears should not touch the edges of the microscopic glass slide. They should appear smooth and without irregularities, streaks, or holes.* *Make sure the frosted side of the microscopic glass slide is facing up when using slides that have a frosted end. Do not place the drop of blood directly on the frosted end; it is used to write the patient information or to affix an aliquot label. Make sure that all slides are properly labeled and double- checked to ensure they match the patient information exactly.*