What is the correct sequence of tubes when drawing blood for testing?

The correct sequence of tubes when drawing blood for testing follows an established order to prevent cross-contamination and ensure accurate test results. The chosen answer reflects this scientifically organized process, beginning with blood cultures. Blood cultures are prioritized first because they are used to detect harmful bacteria or fungi in the bloodstream, and it is crucial that they are collected without contamination from other tubes.

Following this, the light blue tube is next, which is typically used for coagulation studies requiring a specific blood-to-additive ratio. The red tube comes afterward, which is often used for various serological tests and does not contain any additives that could interfere with the tests.

The sequence then moves to gold/tiger top tubes, which contain a gel separator for serum separation, making them ideal for chemistry tests. Next is the green tube, used for lithium levels or other tests that require anticoagulation with heparin. After that is the lavender (or purple) tube, primarily used for hematology tests like a complete blood count (CBC). Finally, the gray tube is used for glucose testing and contains additives that help preserve glucose levels in the sample.

This established order minimizes the risk of specimen contamination and ensures that biochemical reactions in the tests produce reliable results. Each type of tube