ASCP (American Society for Clinical Pathology) Phlebotomy Technician Certification Practice Exam

The correct order of collection for blood culture tubes, coagulation tubes, and hematology tubes is important to avoid contamination and to ensure accurate test results. In this case, the proper sequence starts with the yellow tube, followed by the blue tube, and then the lavender tube.

The yellow tube is used for blood cultures, which require a sterile collection to prevent contamination from outside microorganisms. Collecting this tube first reduces the risk of introducing contaminants that could affect the culture results.

Next is the blue tube, which is utilized for coagulation studies. It contains sodium citrate as an additive, which is crucial for proper coagulation testing. Using the blue tube after the yellow tube ensures that the blood sample for coagulation is not contaminated by any residual anticoagulants from the collection of blood cultures.

Finally, the lavender tube, used for hematology tests, is collected last. This tube typically contains EDTA as an anticoagulant, which is essential for the accurate counting and analysis of blood cells. Collecting it after the other tubes helps to minimize the risk of cross-contamination with additives that might interfere with the hematology tests.

This sequence is based on the principle of collecting the least contaminated samples first, ensuring the integrity of the tests performed from each tube