Blood samples are not usually tested at the same site where the blood is drawn. The blood must be shipped to the laboratory, which can be next door or across town, or hundreds of miles away.
Some laboratories do unique examinations and can be located halfway across the country. Thus, labs have developed standard procedures for the storage and transport of blood samples to ensure there is no interference with the tests.
The method of transport will vary to a certain extent, depending on the tests ordered. The transportation procedures may also differ, mainly according to the way in which the blood was collected.
Whole blood can be stored at 4-8°C for less than 24 hours before the serum is separated. Whole blood cannot be frozen. In order to separate the serum, the blood must be centrifuged for 10 minutes. Then, the serum must be removed carefully with a very small pipette to avoid disturbing the red blood cells.
The serum is transferred into another tube carefully labelled with the patient’s name, identification, and date; it can then be stored. Storage must be between 4-8°C for a maximum of one week or frozen at -20 degrees. Transport of frozen samples is on ice packs.
Collection and transportation of clinical samples is fraught with risk. Venipuncture is usually done in a clinic, a lab, or a hospital because it requires expertise in drawing and processing the samples. Many things can go awry during the sampling event itself, and even more can go wrong afterward.
From the moment the blood is drawn, there is potential for human error. Labels can be applied to the wrong tubes or smeared so as to be illegible. Tubes can roll off onto the floor and smash or be misplaced. Losing a specimen or worse, mixing up samples, can cause legal problems or even destroy lives. Divorces have occurred when a paternity sample was run on the wrong person. People have been treated for diseases they don't have. Or not treated for a disease they do have.
Microsampling is a newer collection method that reduces the time and steps needed for both transport and storage. With one finger prick, the blood is collected by a droplet into capillary tubes, sealed and mailed. It can be done by the patient at home.
The fewer steps in processing there are, the less chance there is for mistakes, and the more reliable the results will be. The traditional venipuncture method opens many chances for errata. New methods may eliminate some of the old risks.