Which tube is most often used for conducting complete blood counts (CBC)?

The lavender top tube is the most commonly used for conducting complete blood counts (CBC) due to its additive, which is ethylenediaminetetraacetic acid (EDTA). EDTA works as an anticoagulant by binding calcium in the blood, preventing clotting, and allowing for the accurate counting of blood cells. This is especially important in a CBC, where the measurement of different cell types, including red blood cells, white blood cells, and platelets, is crucial for diagnosing various medical conditions.

The choice of lavender top tubes ensures that the blood sample remains in a liquid state until analysis, facilitating reliable results. Other tubes, such as those with heparin or without any additives, are not suitable for a CBC as they can affect the blood cell morphology or lead to clot formation, making them less ideal for this test.