Question 63

EDTA should be drawn first for a capillary collection.

In capillary blood collection, the first tube drawn should be the one containing EDTA, as it acts as an anticoagulant and prevents clotting, thereby preserving the integrity of the sample for accurate testing.

A) EDTA

This option is correct because EDTA is an anticoagulant that is essential for preserving blood samples. Drawing this tube first ensures that the sample remains free from clotting, which is crucial for many laboratory tests.

B) Lithium heparin

Lithium heparin is an anticoagulant, but it is not the preferred choice for the first draw in capillary collections. If drawn first, it may not adequately prevent clotting in subsequent tubes, potentially compromising the integrity of other samples.

C) Nonadditive

Nonadditive tubes do not contain any anticoagulants or preservatives, which makes them unsuitable for initial draws in capillary collections. Drawing this type of tube first could lead to clot formation in the sample, resulting in inaccurate test results.

D) Sodium fluoride

Sodium fluoride is used for glucose testing and is an additive that inhibits glycolysis. However, it should not be drawn first in capillary collections because it does not prevent clotting effectively as EDTA does, which is necessary for maintaining sample integrity.

Conclusion

EDTA is the appropriate first draw for capillary blood collection due to its anticoagulant properties, ensuring that the sample remains viable for testing. Other options, while they may serve specific purposes, do not provide the same level of preservation for the sample and could lead to inaccurate results if drawn first.