Certified Medical Assistant (CMA AAMA)Procedures, Examinations and DiagnosticsHard
A medical assistant is instructed to draw both a coagulation panel (light blue-top) and a CBC (lavender-top). If the coagulation tube is the only tube being drawn using a winged (butterfly) collection set, what must be done first?
- ADraw a discard tube before the light blue tube
- BDiscard the coagulation tube and redraw
- CUse a syringe instead of a winged set
- DFill the lavender tube first instead
Show answer & explanationAnswer & explanation
Correct answer: A. Draw a discard tube before the light blue tube
When using a winged blood collection set with tubing, air fills the tubing before blood flow begins. If the citrate tube is drawn first (as the only or first tube), a discard tube must be drawn first to remove the air/dead space and ensure the correct blood-to-additive ratio in the coagulation tube.
Why the other options are wrong
- B. Discarding and redrawing is unnecessary if the discard tube is drawn correctly beforehand.
- C. Switching to a syringe is not the standard solution to this specific tubing issue.
- D. Switching tube order does not address the air-space issue in the tubing.
Winged Set Discard Tube
A non-additive or clotting tube drawn before a coagulation tube when using a butterfly set to eliminate air in the tubing.
- Butterfly tubing contains air that would underfill the first tube
- Discard tube prevents inaccurate blood-to-citrate ratio
- Discard tube can be another light blue or a non-additive tube, per facility policy
Memory trick: 'Butterfly needs a warm-up tube before the real one'