Routine Blood CollectionsDifficulty 3/5
What is the reason the order of draw exists?
- ALaboratory instruments reject specimens whose tubes arrive in the wrong sequence
- BDrawing out of sequence increases the volume of blood required from the patient
- CAdditive carried from one tube into the next can alter the result of the later test
- DTubes filled out of sequence will not develop sufficient vacuum to draw fully
Show answer and rationale
Correct: C. The sequence prevents cross-contamination of additives between tubes. It runs from the tube most vulnerable to contamination toward the additives most likely to interfere.
- D — Vacuum in an evacuated tube is set at manufacture and does not depend on draw order.
- A — Instruments analyse what they are given; they cannot detect the order of collection.
- B — Sequence does not change the volume required for each individual test.