Why should a phlebotomist invert blood collection tubes containing anticoagulants?

Inverting blood collection tubes containing anticoagulants is essential to ensure that the anticoagulant is evenly distributed throughout the blood sample. This action helps prevent clotting by thoroughly mixing the anticoagulant with the blood, which is crucial for maintaining the sample's integrity for accurate laboratory testing. Proper mixing also prevents the formation of clots that could interfere with various hematological analyses.

The other options, while related to blood collection, do not accurately represent the primary reason for inverting tubes with anticoagulants. Facilitating color changes or separating serum from cells are not relevant functions when considering anticoagulant tubes, as they primarily focus on preventing clotting to maintain sample suitability. Additionally, the mixing of hemoglobin and plasma is not a goal of inverting tubes since it doesn't directly relate to preventing clot formation in the presence of anticoagulants.