Common laboratory artifacts caused by inappropriate sample collection and transport: how to get the most out of a sample.

Clinicians are frequently presented with laboratory test results that are not consistent with preconceived expectations for a given case. One important reason for such results is the occurrence of preanalytical errors. In this article preanalytical errors are discussed in 2 parts. The first part covers the steps of sample collection, preparation, and transportation, in which preanalytical errors often occur. This part would be most useful if read in full before collecting a sample. The second part of this article includes a systematic review of preanalytical errors divided according to individual analytes or parameters or, when appropriate, groups of analytes and parameters that represent the same biological system. This part will hopefully serve the clinician as a quick and user friendly guide for identification of possible pitfalls when presented with unexpected laboratory test results for a given case. This article is limited to errors that can affect the complete blood count, chemistry, and coagulation panels.