Which phlebotomy practice is most likely to cause erroneous results in coagulation testing?

Which phlebotomy practice is most likely to cause erroneous results in coagulation testing?

• A. Redirecting the needle several times
• B. Performing a single clean venipuncture
• C. Using proper tourniquet technique
• D. Labeling correctly

Answer: (A)

Coagulation tests depend on a blood sample that hasn’t been activated or contaminated by tissue factors. Any preanalytical trauma that makes the blood start clotting or alters its composition can throw off the results. Redirecting the needle several times causes mechanical injury to the vein and surrounding tissue. This trauma can release tissue factor and activate platelets, which can prematurely start the coagulation cascade or otherwise disturb the clotting balance in the sample. When the blood in the collection tube begins to clot or its coagulation factors are consumed before analysis, the test results become unreliable. A single clean venipuncture minimizes this trauma, helping preserve the sample’s true coagulation status. Proper tourniquet technique and correct labeling matter for overall sample quality and patient safety, but they don’t introduce the same direct coagulation activation risk as repeated needle sticks. So, the practice most likely to cause erroneous coagulation results is redirecting the needle several times.

Coagulation tests depend on a blood sample that hasn’t been activated or contaminated by tissue factors. Any preanalytical trauma that makes the blood start clotting or alters its composition can throw off the results.

Redirecting the needle several times causes mechanical injury to the vein and surrounding tissue. This trauma can release tissue factor and activate platelets, which can prematurely start the coagulation cascade or otherwise disturb the clotting balance in the sample. When the blood in the collection tube begins to clot or its coagulation factors are consumed before analysis, the test results become unreliable.

A single clean venipuncture minimizes this trauma, helping preserve the sample’s true coagulation status. Proper tourniquet technique and correct labeling matter for overall sample quality and patient safety, but they don’t introduce the same direct coagulation activation risk as repeated needle sticks.

So, the practice most likely to cause erroneous coagulation results is redirecting the needle several times.