In the case of a citrate tube that is underfilled, what is the consequence?

In the case of a citrate tube that is underfilled, what is the consequence?

• A. The test results are unaffected
• B. The sample clots
• C. The blood-to-anticoagulant ratio is off, potentially invalidating results
• D. The sample will be more viscous

Answer: (C)

Maintaining the correct blood-to-anticoagulant ratio in a citrate tube is essential for accurate coagulation testing. When the tube is underfilled, there is relatively more anticoagulant than blood, so excess citrate binds more calcium than intended. That extra calcium binding in vitro delays clotting in the assay, leading to artificially prolonged coagulation times and potentially invalid results. In short, the off ratio is the key issue, and the test may need to be redrawn to obtain valid results. The other options don’t fit because citrate’s role is to prevent clotting, not increase it, and underfilling doesn’t make the sample more viscous.

Maintaining the correct blood-to-anticoagulant ratio in a citrate tube is essential for accurate coagulation testing. When the tube is underfilled, there is relatively more anticoagulant than blood, so excess citrate binds more calcium than intended. That extra calcium binding in vitro delays clotting in the assay, leading to artificially prolonged coagulation times and potentially invalid results. In short, the off ratio is the key issue, and the test may need to be redrawn to obtain valid results. The other options don’t fit because citrate’s role is to prevent clotting, not increase it, and underfilling doesn’t make the sample more viscous.