SCFHS Phlebotomy Tech Complete Review Guide 2026–2027

4. The routine adult needle is 21 gauge. A butterfly set is for small or fragile veins such as hand veins in older adults, inserted at about 10–15 degrees.
5. Anchor the vein with the thumb below the site and clean with 70% alcohol, allowing it to dry. Avoid the palmar wrist; a foot vein requires physician approval per facility policy.
6. Older adults have thinner skin and fragile veins that roll, so anchor firmly. Patients on anticoagulants need longer pressure. For a patient with dementia, explain simply and involve the nurse or guardian.
7. CLSI GP41 order: 1 blood culture, 2 light-blue citrate, 3 serum red or gold, 4 green heparin, 5 lavender EDTA, 6 grey fluoride/oxalate. Its purpose is to prevent additive carryover.
8. With a butterfly, a discard tube is drawn first if citrate is the first tube; no discard is needed if a blood culture precedes the citrate. The grey top comes last.
9. Carryover examples: EDTA before serum raises K and lowers Ca (and ALP); heparin before citrate prolongs PT and aPTT. Transferring EDTA blood into a serum tube produces a falsely high potassium such as 7 mmol/L.
10. Fill tubes to the stated volume to keep the blood-to-additive ratio. Citrate is 9:1, a half-full citrate tube is rejected and recollected, and too little blood is called QNS (quantity not sufficient).
11. Mix by gentle inversion, not shaking: citrate 3–4 times, EDTA 8–10 times. Under-mixing causes microclots; vigorous mixing causes haemolysis.
12. Draw errors: wet alcohol or fist pumping causes haemolysis or high K. Keep the arm downward to prevent reflux from the tube. A tube that will not fill with the needle correctly in the vein usually has lost its vacuum. Check the expiry date.
13. If there is a flash but no flow and the vein is felt beside the needle, withdraw slightly and redirect gently. After two failed attempts ask a trained colleague. Withdraw the needle after the last tube is removed, then apply pressure.
14. A plain red glass tube yields serum. Silica particles are the clot activator in plastic red and gold (SST) tubes, and the gel forms a barrier between serum and cells after centrifugation.
15. A gold SST stands upright for about 30 minutes to clot, then is centrifuged capped and balanced. Upright clotting is faster and gives less haemolysis.
16. Green tops hold lithium or sodium heparin, with light green having a gel. They are used for plasma ammonia and STAT chemistry, but not for a lithium level. Gel tubes are unsuitable for some drug levels.
17. Lavender EDTA is for CBC and HbA1c; pink EDTA is for blood bank (type and crossmatch). Grey sodium fluoride suits glucose because it inhibits glycolysis. Royal blue is for trace elements such as lead and zinc.
18. In unseparated blood at room temperature, glucose falls about 5–7% per hour without fluoride. Delay in separating serum raises potassium because it leaks from the cells.
19. Special samples: cold agglutinins are kept at 37 °C; ACTH, PTH and often ammonia are transported chilled and processed promptly; a blood alcohol test needs a non-alcohol antiseptic; cortisol is highest in the early morning.
20. Label at the bedside after the draw with two identifiers, date and time, and collector's initials. Transport specimens upright in a sealed biohazard bag, and collect STAT requests from the emergency department first.

Common mistakes in this chapter

• ✕ Do not rely on the bed number or on asking 'Are you Mr X?'. Have the patient state name and date of birth, and if the date of birth differs from the wristband, do not draw until it is resolved.
• ✕ A patient is eating and fasting glucose is ordered: do not draw, and notify the nurse to reschedule, rather than drawing and noting 'non-fasting'.
• ✕ Never draw above an IV infusion site: a sample above a dextrose infusion gives a very high glucose and must be recollected from the other arm.
• ✕ Fist pumping during the draw falsely raises potassium, as does delayed separation of serum or refrigerating an unspun sample.
• ✕ A sharp electric-shock pain down the arm suggests nerve involvement: remove the needle immediately; do not continue or probe.
• ✕ EDTA drawn before serum affects results as falsely high potassium and low calcium, not the reverse.
• ✕ Never pour blood from one tube into another. When using a syringe, transfer with a safety device in the order of draw.
• ✕ Do not give a patient his results; they come from the ordering clinician. If the patient refuses, respect the refusal, inform the nurse or clinician and document.