c6-PREPARING LABORATORY SPECIMENS FOR STORAGE OR TESTING.docx

CHAPTER 6 ========= Processing Specimens ==================== OVERVIEW -------- Correct specimen collection, preparation for transport, handling, and quality control are essential for each test to be accurate. You must sometimes perform point-of-care (POC) testing or send samples to reference lab...

CHAPTER 6 ========= Processing Specimens ==================== OVERVIEW -------- Correct specimen collection, preparation for transport, handling, and quality control are essential for each test to be accurate. You must sometimes perform point-of-care (POC) testing or send samples to reference laboratories where correct handling is necessary for ensuring accurate test results. Errors in collection might go unnoticed, causing inaccurate results and possible rejection, and often require re-collection of specimens. Chain-of-custody guidelines help maintain control of and accountability for specimens for forensic studies, blood alcohol content (BAC), and drug screening. You must be especially aware of the means of electronic data input, retrieval, and communication with non-laboratory personnel. Distribution of laboratory results-including those that are critical values-are transmitted via electronic health records and software systems. Objectives ---------- Upon completion of this chapter, you should be able to: - Prepare samples for transportation within the facility or to a reference (outside) laboratory. - Transport specimens according to handling requirements (temperature, light, time). - Adhere to chain-of-custody guidelines for specific types of specimens (forensic studies, blood alcohol levels, drug screens). - Coordinate communication with non-laboratory personnel for processing and collection. - Use technology to input and retrieve specimen data. - Report critical values for point-of-care testing. - Distribute laboratory results to ordering providers. PREPARING LABORATORY SPECIMENS FOR STORAGE OR TESTING ===================================================== After ensuring the patient\'s safety and completing the venipuncture procedure accurately, the next step is to process the specimen and properly transport it to the laboratory. Laboratories face challenges with time management, test accuracy, specimen rejection, and specimen transportation processes. Abide by any specific handling requirements for the requested test in a timely manner to ensure accurate results. The time it takes for the entire process-including ordering, specimen collection, transportation, processing, analysis, and reporting-is the turnaround time. In a hospital or a large laboratory facility, you will handle specimens and perform testing on-site. Whether you are performing tests on-site, working in a reference laboratory, or performing POC testing, it is imperative to follow specimen-handling processes with accuracy. Prior to processing, important steps in handling and transporting include mixing the sample, creating aliquots, adding diluents, centrifuging, packaging the labeled specimen in a biohazard bag, and following thermal and light-sensitivity procedures. When tubes contain an additive, invert them gently to mix the additive with the blood and to distribute the additive evenly throughout the sample. Mix it as soon as possible after the collection. Shaking the tube can result in a hemolyzed specimen. Not mixing it enough can result in the formation of clots, which can alter the test results. It is not necessary to mix blood samples in tubes that do not contain additives. Special handling ---------------- Special handling is a requirement for transporting some specimens. - **Thermolabile specimens** - Use a heat source or heat blocks to regulate temperature. - Use ice slurries, refrigerators, or freezers for chilling purposes. Do not use cold or ice packs. - Avoid fluctuating temperatures. - **Photosensitive specimens** - Protect these from light. Tests that require special handling of specimens include ammonia and lactic acid, for which the blood tube must sit in an ice slurry (a thick mixture of water and ice) immediately after collection. For cold agglutinins, the sample must remain at body temperature-37° C (98.6° F). Protect blood samples for bilirubin and folate levels by wrapping the blood tube in foil. Blood gas tests can be stored at room temperature for 15 to 30 minutes or in an ice slurry for up to 1 hour. Delivery speed is crucial to prevent the loss of gases from the blood prior to analysis. For coagulation tests, analysis should take place within 1 hour of collection. Prothrombin time (PT) is an exception. A delay up to 24 hours at room temperature will not affect the results. Room temperature for laboratory purposes is 22° C (71.6° F). Centrifuging ------------ Some specimens require centrifuging or other additional processing prior to transporting them to the reference laboratory. Specimens that require separating the serum or plasma from the cells require centrifuging. To use the correct centrifuge, be aware of the tube type, rotor, spin time, capacity, noise level, and proximity to other equipment. Some centrifuges accommodate only a few tube sizes, while others have adapters for various sizes. The type of rotor can produce either a flat gel barrier (which is best for immunoassay and chemistry tests) or an angled gel barrier (which can be problematic for some chemistry tests). The steps of centrifuging include the following: - **Pre-centrifugation** is the handling and processing of specimens after collection and before centrifugation. It is important that the process begins as soon as possible after collection; the delay in separating plasma from cells should not exceed 2 hours. If a specimen for centrifugation does not have an anticoagulant additive, it should clot before going into the centrifuge. Clotting usually takes 30 to 60 minutes at room temperature. Do not chill these samples, because that will delay clotting. If the patient is taking an anticoagulant, that will also delay clotting. Be sure to protect any photosensitive specimens from light, either by wrapping them in foil or placing them in an amber specimen container. Shield photosensitive specimens from light as much as possible during the process. - **Centrifugation** is the processing of specimens by spinning them in a centrifuge at high speeds, forcing the heavy elements of the specimen (blood cells) to move to the bottom of the tube and the lighter substances (serum, plasma) to remain at the top. The time and speed of centrifugation are critical elements the laboratory and the centrifuge manufacturer establish. These procedures should be clear and available in every laboratory. If the time in the centrifuge is inadequate, portions of blood cells can remain in the serum or plasma and affect test results. It can also result in incomplete formation of the barrier gel. Place tubes in the centrifuge with their stoppers or caps on. Balance them so that tubes of the same size and that are holding the same volume of blood are opposite each other. Without that balance, they are at higher risk for breakage. Never open the lid of the centrifuge before it has completely stopped spinning. Do not centrifuge specimens more than once. - **Post-centrifugation** is the handling and processing of specimens once the centrifugation process is complete and removal of the serum or plasma is necessary. Removal is best immediately after centrifugation and no longer than 2 hours later. Serum might require room temperature, refrigeration, freezing, or protection from light, depending on the test it will undergo. In general, serum and plasma should remain at room temperature no longer than 8 hours before testing. Otherwise, it needs refrigeration. If testing does not take place within 48 hours, then freezing is necessary. Some specimens have time limits and temperature requirements after centrifuging-room temperature, refrigeration, storage in the dark, or freezing-depending on the testing requirements. Aliquoting ---------- Aliquot specimens right after completing the centrifugation process. To aliquot a sample, hold the empty tube adjacent to the specimen tube, use a disposable pipette to transfer the serum (without cells) from the specimen tube to the aliquot tube, and label the specimen accordingly. Packaging --------- When transporting specimens via postal service mail or express delivery services, be sure to comply fully with local, state, and federal laws that govern their special packaging and biohazard identification. Complete shipping paperwork, including the patient\'s identification, specimen identification, and test information. To prepare samples for transportation to a reference laboratory, package the specimens using the following supplies: - Original specimen tubes or plastic screw-cap transfer tubes - Absorbent materials - Watertight primary containers - Watertight secondary containers (resealable bags, plastic canisters, foam boxes) - Strong outer packaging (fiberboard boxes or mailing tubes, wooden boxes, rigid plastic containers) - Coolants (ice packs, dry ice), if necessary Placing in biohazard bags ------------------------- Prior to placing specimens in biohazard bags, be sure to label the specimen with the patient\'s full name, the date and time of the specimen collection, and the source and type of specimen. To prepare these samples correctly, place the labeled specimen into a biohazard bag and then into a primary container with absorbent material surrounding it and usually above any necessary coolants. Place all of these materials within the secondary container and place the specimen documentation above the secondary container. The documentation may have a separate bag. Make sure to use this bag and seal if required. Then place the secondary container and the documentation inside the shipping container.