National Phlebotomy Certification Practice Exam 2026 - Free Phlebotomy Practice Questions and Study Guide

The example of a preanalytical error made during blood collection is accurately represented by the choice of failing to mix tubes. This step is crucial because when blood is collected into different types of tubes, additives may be present to preserve or enhance the sample for laboratory testing. If the tubes are not mixed properly, the blood may not adequately interact with these additives. This can lead to factors such as clotting in anticoagulant tubes or improper reactions in other types of tubes, ultimately compromising the integrity of the sample and the accuracy of the test results.

Other options illustrate different types of preanalytical errors, but failing to mix the tubes directly affects the sample's quality, which emphasizes its significance. For example, incorrect labeling of tubes is a critical error, but it pertains more to the identification and tracking of specimens rather than the collection process itself. Using expired tubes can lead to deteriorated additives or compromised sterility, yet this also falls under different forms of error. Collecting blood from an infected site is relevant to patient safety and potential contamination of the sample, but it typically relates to infection control practices rather than the immediate processes affecting the sample itself during collection. Thus, the act of failing to mix tubes after collection closely aligns with the preanalytical phase