Final answer:
A CBC must be run within 2 hours of drawing blood to ensure accurate results as cellular components can change over time. Blood samples are processed using various methods, including centrifugation and quenching with methanol. In emergent situations with no time for blood typing, Type O- blood is used due to its universal donor status.
Step-by-step explanation:
When a Complete Blood Count (CBC) is ordered, it is essential that the test be run within 2 hours of drawing the blood. This timeframe is crucial because after blood is drawn, cellular components can change due to metabolic processes such as glycolysis and cell lysis. For example, if a blood sample sits for over an hour in a glass tube, clotting typically occurs, and the serum is then harvested from the clotted cells - this serum will contain breakdown products that could affect certain measurements if too much time elapses.
Similarly, if a person's blood glucose is tested and found to be normal within 1.5 hours of eating, it suggests that their insulin response is functioning properly, indicating that they are not diabetic as shown by Graph-A. Blood samples collected into tubes containing anticoagulants like lithium heparin or K2EDTA are centrifuged to obtain plasma, which is the liquid portion of the blood. Plasma samples must be processed correctly, which may involve quenching with methanol before analysis to prevent changes in the blood chemistry.
In emergency situations where there is no time for blood typing, like a severe accident, a patient is often transfused with Type O- blood because it is considered the 'universal donor' and has the least risk of causing an adverse reaction. In pre-surgery blood type testing, visibility of agglutination when anti-A and anti-B antibodies are added indicates the presence of both A and B antigens, which would classify the blood type as AB.