The second major variable to control during sample transportation is temperature. For laboratories that service outreach testing, in which couriers or delivery services are used to transport samples, efforts must be implemented to provided controlled temperatures during transit. Coolers with ice blocks or portable refrigerated units help to maintain a constant temperature to help preserve the sample integrity.
Even for transit within the hospital, or delivery within a clinic or medical center campus where samples are hand-delivered, care must be taken to maintain the temperature to minimize the pre-analytical variability that occurs during sample delivery. Blood gases, ammonia, lactic acid, and many coagulation tests require that the sample be immediately placed on ice to help retain the measurands of interest. Failure to do so in a conscience and time-efficient manner may result in erroneous results, which in turn may delay treatment, lead to incorrect treatment, or result in misdiagnosis.