NHA Phlebotomy Certification Practice Exam

To prevent blood from clotting, the specimen must be:

1. Collected in a tube containing an anticoagulant

2. Inverted right after collection

3. Centrifuged right after collection

4. Both a and b

The correct answer is: Both a and b

To ensure that blood does not clot after collection, it is critical to use a tube that contains an anticoagulant. Anticoagulants are substances that prevent the coagulation process by inhibiting certain steps in the clotting cascade, allowing for the preservation of the blood sample in its liquid state for accurate testing and analysis. Common anticoagulants used in phlebotomy include EDTA, heparin, and citrate, which are found in specific collection tubes designed for various tests. In addition to using an anticoagulant, inverting the tube immediately after collection is also important. This mixing process ensures that the anticoagulant is evenly distributed within the blood sample, preventing localized clotting and maintaining sample integrity. Inverting the tube assists in adequately mixing the blood with the anticoagulant, which is essential for reliable test results. While centrifugation is a procedure that separates blood components after clotting and is part of subsequent processing, it does not play a role in preventing clotting during the initial collection. Therefore, using an anticoagulant and inverting the collection tube after obtaining the sample together fulfill the requirements to prevent clotting effectively.