Not surprisingly, the timeline within which a blood sample should be delivered to the laboratory for testing is contingent on a number of factors, not least of which is the manner in which the sample has been treated since its extraction from the patient. One of the laboratories that conducts tests on specimen in Quest Diagnostics, which, in its guidelines for medical staff on how to handle specimen, recommends the following:
"The patient must first be properly prepared so that the best possible specimen can be collected. Next, the actual collection of the specimen must be completed. Then, the specimen should be properly processed, packaged and transported to the laboratory in a timely manner and under environmental conditions that will not compromise the integrity of the specimen." [Emphasis added]
Having consulted a number of websites, including the U.S. Centers for Disease Control, the consensus on a timeline for transporting a blood specimen is that time is less important than whether the specimen is properly packaged and stored -- in effect, has it been preserved at the proper temperature and, if an infectious disease is suspected, has it been properly secured. Guidelines otherwise vary according to the precise nature of the specimen, even within the category of "blood."
A British website, Guidelines for the Blood Transfusion Services in the UK, reads as follows:
"Transportation from collection site to processing centre: Blood and samples from donor sessions must be transported to the receiving Blood Centre under appropriate conditions of temperature, security, and hygiene."
In short, specifying a timeline appears to be less important than ensuring that the specimen is properly handled.