NHA Certified Phlebotomy Technician (CPT)Collection RoutineMedium
A phlebotomy technician is collecting a blood specimen for a blood culture. Which of the following is the most critical step to prevent contamination?
- ACleaning the venipuncture site with povidone-iodine.
- BDrawing the aerobic bottle before the anaerobic bottle.
- CAllowing the antiseptic to air dry completely.
- DInverting the blood culture bottles gently after collection.
Show answer & explanationAnswer & explanation
Correct answer: C. Allowing the antiseptic to air dry completely.
Allowing the antiseptic to air dry completely ensures maximum antimicrobial action. If the antiseptic is not dry, it will not effectively kill skin flora, increasing the risk of contaminating the blood culture specimen.
Why the other options are wrong
- A. Cleaning with povidone-iodine is part of the process, but the effectiveness relies on proper drying time, making 'allowing to air dry' more critical for contamination prevention.
- B. While there's an order of draw, the specific order of aerobic before anaerobic is less critical for contamination than proper site antisepsis.
- D. Inverting bottles gently is important to mix blood with the culture medium, but it does not prevent contamination from skin flora during collection.
Antiseptic Drying Time
The required time for an antiseptic solution to fully evaporate and exert its maximum antimicrobial effect on the skin.
- Crucial for preventing microbial contamination of blood cultures.
- Alcohol-based antiseptics typically dry faster than povidone-iodine.
- Do not fan or blow on the site to accelerate drying, as this can reintroduce contaminants.
- Inadequate drying is a common cause of false-positive blood cultures.
Memory trick: Clean, Dry, Draw – that's how you keep germs away!