6.2 Order-of-Draw & Scenario Drills
Key Takeaways
Rapid recall is the goal: you should produce the full CLSI PRE02 order of draw and each tube's additive in under ten seconds without reasoning it out
Tube-to-test matching is a guaranteed item type — lavender/EDTA equals CBC, light blue/citrate equals PT/INR/aPTT, gray/fluoride equals glucose, gold SST equals serum chemistry
Complication scenarios test the immediate action, not the diagnosis — remove the needle for nerve pain, lower the head for syncope, apply pressure for a hematoma
Special-collection antiseptic items hinge on one rule: alcohol for routine, chlorhexidine for cultures, non-alcohol for blood alcohol levels
Capillary collection reverses the order of draw — EDTA/lavender is filled before serum tubes to avoid platelet clumping and clotting
How to Use These Drills
Quick Answer: Pattern recognition wins this exam. The order of draw, tube-to-test pairings, and immediate complication actions appear as the same question structures every time. Drill them until the answer is automatic, then the exam becomes a recall exercise instead of a reasoning exercise.
Work each quiz below cold — do not look back at Section 6.1 first. If you miss one, write the underlying rule on a single index card and re-drill it the next day. The goal is speed plus accuracy: on a 120-item, 2-hour exam you have roughly one minute per item, and recall items should take you ten seconds so you can spend time on the reasoning items.
The Self-Test Sequence
- Recite the order of draw out loud: culture, light blue, red/SST, green, lavender, gray.
- For each tube, say the additive and one test.
- State the inversion count for lavender, light blue, green, and red.
- For three complications, state the first action in five words or less.
If any step stalls, that is your weak spot for the final week.
Tube-to-Test Quick Map
Use this table only to check yourself after the drills, not before them.
| Test ordered | Correct tube | Additive |
|---|---|---|
| CBC, ESR | Lavender | EDTA |
| PT, INR, aPTT | Light blue | 3.2% sodium citrate |
| STAT electrolytes / plasma chemistry | Light green PST or green | Lithium/sodium heparin |
| Serum chemistry, serology | Gold SST or red | Clot activator + gel / none |
| Glucose, lactate, blood alcohol | Gray | Sodium fluoride / potassium oxalate |
| Blood culture | SPS bottles | Sodium polyanethol sulfonate |
| Type and crossmatch (blood bank) | Pink | EDTA |
Inversion Reminders
- Red plain: 0 inversions (no additive to mix).
- Light blue: 3-4 gentle inversions.
- Gold SST: 5 inversions.
- Green, lavender, gray: 8-10 inversions.
- Mixing is always gentle — never shake, which causes hemolysis.
A single venipuncture must fill these tubes: blood culture set, gray, light blue, and lavender. What is the correct fill order?
Light blue, blood culture, lavender, gray
Blood culture, light blue, lavender, gray
Blood culture, lavender, light blue, gray
Gray, blood culture, light blue, lavender
A provider orders a PT/INR and a CBC on the same patient. Which tubes are required?
Light blue for PT/INR and lavender for CBC
Lavender for PT/INR and light blue for CBC
Gold SST for PT/INR and green for CBC
Gray for PT/INR and lavender for CBC
Midway through a venipuncture the patient reports sudden, severe shooting pain radiating down the forearm. What should the phlebotomist do first?
Reposition the needle slightly and continue
Loosen the tourniquet and continue the draw
Immediately remove the needle and discontinue the draw
Ask the patient to make a fist to distract from the pain
A phlebotomist must collect a capillary specimen requiring both an EDTA microtube and a serum microtube. In what order should they be filled?
Serum microtube first, then EDTA microtube
EDTA microtube first, then serum microtube
Order does not matter for capillary collection
Both must be filled simultaneously
A blood culture and a routine chemistry draw are ordered. Which antiseptic is correct for each site preparation?
70% alcohol for the culture; chlorhexidine for the chemistry
Chlorhexidine gluconate for the culture; 70% alcohol for the chemistry
Benzalkonium for both collections
Povidone-iodine for the chemistry; 70% alcohol for the culture
Sections you finish are checked off in the contents.