Which color-top tube is used for coagulation testing such as PT and APTT?

Prepare for the CAMLPR Specimen Collection Competency Test. Practice with diverse question sets including multiple-choice and flashcards. Each question includes hints and explanations to help you become proficient before the exam.

Coagulation testing relies on plasma whose clotting factors remain functional, which is achieved by using a citrate anticoagulant. A blue-top tube contains sodium citrate, which binds calcium to prevent clotting during collection and transport. This preserves the plasma so PT and APTT can be measured accurately once calcium is reintroduced in the lab. Maintaining the correct blood-to-anticoagulant ratio (about 9:1) and gently mixing the sample are essential to avoid distortions. After collection, the blood is centrifuged to obtain platelet-poor plasma for testing. Red-top tubes lack an anticoagulant and will clot; lavender-top tubes contain EDTA and chelate calcium (used for CBCs); green-top tubes contain heparin, which can interfere with some coag tests. Thus, the blue-top citrate tube is the appropriate choice for PT and APTT.