Final answer:
The preanalytical phase includes the processes before testing, such as test ordering, specimen collection, and preparation. Blood samples may be collected, centrifuged, and prepared with specific protocols, involving professionals like phlebotomists and medical technologists to ensure sample integrity.
Step-by-step explanation:
The preanalytical phase of laboratory procedures includes all the processes that occur before the actual testing phase. This phase includes selecting the appropriate test to order, collecting the specimen in a proper manner (such as venipuncture), and preparing the specimen for analysis, like ensuring it's in the correct container with the required preservatives or anticoagulants. For instance, when blood samples are collected into tubes containing K2EDTA, they are centrifuged to obtain plasma, and the plasma is often quenched with methanol before analysis. Urine samples may sometimes be analyzed with no preparation.
During the preanalytical phase, if a lab technician collects a blood sample in a glass tube and waits about an hour before harvesting serum, during this time, blood cells are separating from serum due to coagulation and sedimentation - heparin or other anticoagulants may be used to prevent clotting if plasma is required.
Professionals like phlebotomists and medical technologists are key players in this phase. Phlebotomists draw the blood, ensuring proper collection techniques, while medical technologists may handle and prepare the specimens for the tests that follow. For samples to be analyzed, it's important to follow protocols that minimize interference from endogenous and exogenous substances and concentrate the analytes to enhance the sensitivity of the method.