Final answer:
Blood specimen collection should follow a specific order: EDTA tubes for hematology, SST or red top tubes for serum chemistry, and sodium citrate tubes for coagulation studies. Serum is collected after the blood clots, and coagulation studies require plasma with intact clotting factors. Agglutination with both anti-A and anti-B antibodies indicates type AB blood during blood typing.
Step-by-step explanation:
The proper order for the collection of blood specimens for various tests is crucial to ensure the accuracy of the results. For hematology testing, blood is usually collected in tubes with an anticoagulant such as K2EDTA. This prevents clotting and allows for the analysis of whole blood for hematology studies. For serum chemistry testing, blood is allowed to clot in a tube, typically a serum separator tube (SST) or red top tube, and then centrifuged to separate the liquid portion (serum) from the clot. Serum is the fluid part of the blood after the blood cells and the clotting proteins have been removed, used for various chemistry tests. Lastly, for coagulation studies, blood is collected into tubes containing sodium citrate to prevent clotting. This plasma sample is then used to assess the coagulation pathways and clotting factors.
During the process of serum preparation, the blood sample remains in the glass tube for about an hour to clot adequately before being centrifuged to harvest the serum. This clotting process is important because it yields serum free from clotting factors, which could interfere with certain tests. During blood typing, if both anti-A and anti-B antibodies cause agglutination in a patient's blood sample, it indicates that the patient has type AB blood, which is a normal response and not an error by the technician.
Cross matching and determining blood type are essential before a blood transfusion, but in emergent situations where hemorrhage poses an immediate threat to life, type O blood may be used as it is considered the universal donor type.