Prewarming Information and Courses from MediaLab, Inc.

Cold antibody Immediate spin screen and panel cell reactions will be positive (W+ to 4+). The auto control may also be positive. AHG reactions may be weakly positive if the cold antibody is bound strongly to the red cells. Prewarming should prevent binding from occurring. So, prewarm panels and tests should have negative reactions.Warm antibody Immediate spin screen, panel cell and auto control usually not positive. AHG reactions will be positive including auto control (W+ to 4+). Prewarming of sample and reagents will not change positive reactions since they react best at 37°C and AHG phase. So, reactions will still be positive. Elution and autoadsorption techniques may be used to help further identify the antibody or to help identify other clinically significant antibodies that may be present.AutoadsorptionAutoadsorption is a technique that involves adsorbing unbound autoantibody from the patient's serum using the patient's own red cells. Once the autoantibody is removed, then testing can be performed to determine if any clinically significant antibodies are present.

Reactions are occurring strongly in IS phase but are weaker in AHG phase which could be due to some disassociation of the cold antibody occurring at the warmer testing phase.Prewarming of all reagents and sample will prevent binding of cold antibody. If the W+ reactions at AHG are due to residual cold antibody, the reactions should be negative with a prewarmed panel. No IS phase reading is performed. Prewarmed Panel

Procedural Step Comment Caution Greet and positively identify patient Always use at least two patient identifiers to ensure positive patient identification. Never rely on name placards that are placed on or near the patient's bed or crib to identify the patient. If there is a discrepancy in identification, do not proceed until the discrepancy is resolved. Explain the procedure If the patient is a small child, be at eye level when explaining the procedure. Also explain the procedure to the parent(s). If the patient is aware of what will be happening there is less chance of the patient suddenly jerking away his/her hand when the puncture occurs. Position patient appropriately An outpatient who is a small child should sit on the parent's lap. If necessary, seek assistance for finger puncture if the patient is a small child. Cleanse hands and put on gloves Use soap and water or alcohol-based gel to cleanse hands. Cleanse hands before donning gloves and after removing gloves. Warm puncture site if needed Use the method that is approved by the laboratory for prewarming the puncture site. Never use a moist cloth that has been heated in a microwave as this may cause injury to the patient. Gather appropriate equipment Only have needed equipment at hand. Keep track of ALL equipment to prevent patient injury. Cleanse the puncture site Use 70% isopropanol unless the patient is sensitive to alcohol. Allow the site to air dry. Performing the puncture before the alcohol has dried may hemolyze the blood specimen. Securely grasp and puncture finger Puncture the side edge of the fleshy pad of fingertip. Avoid extreme side and tip of finger. Discard puncture device into appropriate container Puncture device should be discarded into a sharps container that is puncture-proof, has rigid sides, and has a lid Do not discard puncture devices into regular trash or biohazard bags. Injury to personnel who handle these bags may occur. Wipe away the first drop of blood Use slight pressure to facilitate blood flow. The first drop of blood contains tissure fluid that may contaminate or dilute the blood specimen and affect test results. Collect blood into container Allow blood to flow freely into the collection device. Tap the container gently on a hard surface to move blood further down into the tube if necessary. Do not "milk" the finger or scrape the collection device across the finger to obtain specimen; both actions may cause the specimen to hemolyze. Mix specimen immediately upon completion of the collection. Apply pressure to the puncture site to stop the bleeding. Use gauze to apply pressure to the puncture site. It is not advisable to apply an adhesive bandage over the skin puncture site if the child is less than two years old as the child may place the bandage in his/her mouth. Label specimen Specimen must be labeled in the presence of the patient. Unlabeled specimens will be rejected by the laboratory.