Phlebotomy 118 – Week 2: Blood Collection Fundamentals

Lesson Objectives

• Equipment literacy
  • Identify all apparatus used in blood collection (needles, holders, tubes, tourniquets, etc.)
• Procedural mastery
  • List the complete step-by-step workflow for each specimen-collection method
• Method comparison
  • Differentiate venipuncture, butterfly (winged-infusion), and capillary/dermal puncture
• Patient communication
  • Explain prep instructions (fasting, medication holds, comfort measures) in clear lay terms
• Patient identification (ID)
  • Apply the verbal/label two-identifier rule every time
• Venipuncture prep (evacuated-tube method)
  • Select correct tube, additive, gauge, and site
• Tube recognition
  • Match tube color → additive → primary test panels

Key Terms & Definitions

• Phlebotomy – incision into a vein for blood removal
• Venipuncture – puncturing a vein with a hollow needle to obtain blood
• Capillary / Dermal puncture – superficial skin lance for small volumes
• Arterial puncture – sampling arterial blood to evaluate \text{O}2, \text{CO}2, \text{pH}
• Additive – any chemical placed inside a tube (anticoagulant, clot activator, gel)
• Inversion – gentle 180° flips (never shake) to mix additive with blood
• Hemoconcentration – plasma water diffuses into tissues ➔ artificially high cell counts
• Venous stasis – pooled, stagnant blood from prolonged tourniquet use (> 1 min)
• Gauge – internal diameter of needle (smaller number = larger bore)
• Fistula/Port – surgically created access; avoid unless ordered

Venipuncture & Phlebotomy Fundamentals

• Purpose: provide specimens for diagnosis, monitoring, blood donation
• Common volumes
  • Capillary: a few drops
  • Routine venipuncture: several milliliters via vacuum tubes
  • Therapeutic phlebotomy / donation: >450\,\text{mL} using 16\text{–}18\,\text{g} needles
• Arterial sampling used to check respiratory status; normal \text{O}_2 saturation 95\text{–}100\%

Venipuncture Sites (Upper Limb First-Choice)

• Antecubital fossa (inner elbow)
  • Median cubital vein (central, anchored; safest)
  • Cephalic vein (lateral; helpful in obese pts)
  • Basilic vein (medial; near brachial artery—extra caution)
• Hand (dorsal metacarpal)
  • Superficial, more mobile; ↑ chance of rolling & post-draw swelling
• Forearm
  • Small superficial veins; common for pediatrics
• Foot/ankle
  • Physician permission required; last resort (poor circulation ↑ infection risk)
• Special caution
  • Accidental arterial puncture ➔ apply firm pressure & report

Sites to Avoid

• Hematomas, burns, scars, eczema
• Post-mastectomy limb
  • Unilateral ➔ draw from opposite arm
  • Bilateral ➔ use distal site (hand/foot) with approval
• Arms with IV fluids ➔ select opposite arm or distal to IV line
• Vascular access devices (ports, fistulas) unless specifically ordered

Blood Collection Methods

1. Evacuated Tube System (ETS)
   • Straight needle + plastic holder + color-coded vacuum tubes
   • Site: antecubital area, large veins
   • Needle sizes: 21\text{–}22\,\text{g}; length 1''\text{–}1.5''; insertion angle 15\text{–}30^\circ
2. Butterfly (Winged-Infusion) Set
   • Flexible wings; tubing minimizes vein collapse
   • Any body site; antecubital 15\text{–}30^\circ, other sites 0\text{–}10^\circ
   • Gauges: 21\, 23, 25\,\text{g} (23 g most common)
3. Syringe Method
   • For fragile or collapsing veins; manual negative pressure
   • Alone (straight needle) or mated to butterfly
   • Blood must be transferred to tubes ➔ ↑ accidental stick risk
   • Limited volume; follow same angles as corresponding needle type

Essential Equipment & Supplies

• Tourniquet
  • Single-use preferred (latex or latex-free)
  • Placement: 3\text{–}4'' above puncture; snug but not tight; max time 60\,\text{s}
• Needle holder (hub) with safety flange
• Needles (sterile, single use, bevel up)
  • Routine 21\text{–}22\,\text{g}; donation 16\text{–}18\,\text{g}; butterfly 21\text{–}25\,\text{g}
• Tubes (vacutainers) – color coded; pre-set vacuum volume
• Skin antiseptics
  • Alcohol 70\%, iodine, or chlorhexidine (per test requirement)
• Gauze 2''×2''
• Adhesive bandage or COBAN
• Gloves (non-sterile)
• Sharps container (immediate needle disposal; entire holder + needle per OSHA)

Tourniquet: Technique & Physiology

• Purpose: slow venous return to distend veins (NOT stop arterial flow)
• Over-tight/long application effects
  • Venous stasis ➔ hemoconcentration ➔ false ↑ in RBCs, proteins, iron, calcium, etc.
  • Hemolysis if >1 min ➔ compromised results
• Release sequence
  1. Remove tourniquet before removing final tube & withdrawing needle
  2. Immediate gauze pressure to avoid hematoma

Patient Preparation & Identification

• Two identifiers: ask patient to state full name & DOB; cross-check with requisition & tube labels (never lead with a yes/no question)
• Pre-test questions
  • Fasting status (e.g., 12\text{–}14 h for lipid panel, GTT)
  • Current medications (anticoagulants, insulin)
  • Allergies (latex, adhesive)
  • History of fainting / syncope
• Provide clear instructions (fasting, hydration, what to expect)

Step-by-Step Venipuncture (ETS Example)

1. Review order, lab manual, assemble supplies
2. ID & greet patient, explain procedure, verify fasting & meds
3. Hand hygiene & glove donning
4. Position patient; extend arm supported
5. Apply tourniquet, palpate vein (width, depth, direction) with index finger
6. Release tourniquet while cleansing site with alcohol; air-dry ≥30 s
7. Re-apply tourniquet; inspect needle (bevel up) & remove cap
8. Anchor skin distal to site; insert needle at 15\text{–}30^\circ smoothly
9. Advance tube onto hub flange; allow to fill until flow ceases
10. Follow Order of Draw (see section below)
11. Before last tube fills, release tourniquet
12. Remove final tube, withdraw needle, activate safety, apply gauze pressure \geq30 s
13. Label tubes in patient’s presence (name, DOB, date/time, MA initials)
14. Check hemostasis, bandage, post-care instructions (avoid heavy lifting \geq30 min)

Blood Collection Tubes & Order of Draw

Purpose: prevent additive carryover that alters analytes

1. Yellow – SPS / ACD (Microbiology, DNA)
2. Light Blue – \text{Na} Citrate (Coagulation) – 9:1 blood:additive ratio; fill line critical
3. Red – None (Serology, Blood Bank, Drug levels)
4. SST (Tiger/Gold) – Clot activator + gel (Comprehensive/Basic Metabolic Panels, Lipid, PSA)
5. Green – Heparin (ABG, STAT plasma chemistry)
6. Lavender – EDTA (CBC, ESR, HgbA1c)
7. Gray – \text{K}_2\text{Oxalate} + \text{NaF} (GTT, FBS, Blood Alcohol)

Tube-Specific Notes

• Yellow (SPS)
  • Strict aseptic 2-step skin prep (alcohol then iodine/chlorhexidine)
  • Collect two bottles: anaerobic then aerobic
  • Diagnoses: septicemia, unexplained fever
• Light Blue
  • Fill completely; tests within 2 h (PT, aPTT, BT, INR)
  • DVT & coagulation factor disorders
• Red
  • Glass: no clot activator; Plastic: clot activator
  • ABO typing, \beta-hCG (qual & quant), HIV serology
• SST (Tiger/Gold)
  • Allow clot 30\text{–}60 min before centrifuge; spin within 1 h to avoid glycolysis
  • Contains thixotropic gel for serum–cell barrier
• Green
  • Sodium or lithium heparin; STAT chemistry & ABGs
  • ABG: radial/femoral artery; transport on ice within 15\text{–}30 min
• Lavender
  • EDTA preserves cellular morphology
  • Hematology: CBC (RBC, WBC, plt), ESR (inflammation), HgbA1c (3-mo glucose avg)
• Gray
  • Oxalate anticoag + fluoride glycolysis inhibitor
  • GTT protocol: verify fasting, collect baseline blood & urine, administer 50\text{–}100\,g glucose drink in \leq5 min, timed draws q1h (abort if vomiting)
  • Legal blood alcohol ➔ chain of custody; no alcohol skin prep

Equipment Safety & Quality Control

• Always use same manufacturer (tube + holder + needle) for fit & vacuum integrity
• Inspect tubes for cracks, expiration date, additive volume; discard compromised stock
• Safety devices
  • One safety per system; activate on hard surface, never body part
  • Dispose immediately in sharps; needle & holder stay connected
• Tube handling
  • Additive tubes: invert specific times (e.g., Lavender 8\text{–}10×, Light Blue 3\text{–}4×)
  • Never shake ➔ hemolysis
  • Serum tubes must clot before centrifugation; incomplete clot ➔ fibrin strands & ↓ serum yield

Special & Ancillary Procedures

• Arterial Blood Gas (ABG)
  • Drawn by trained personnel; radial artery Allen’s test first
  • Transport on ice; analyze STAT for \text{pH},\ \text{PaO}2,\ \text{PaCO}2
• Chain of Custody (Forensic Alcohol, Drug screens)
  • Sequential documentation of specimen handlers
  • Tamper-evident seals; non-alcoholic skin cleanser
• Small/Fragile Vein Algorithm
  • Prefer butterfly or syringe with pediatric volumes (short draw tubes)
  • Example order request: BhCG, GTT, BMP, ABO ➔ use Red, Gray, Tiger, Red; maintain draw order Gray last due to fluoride

Ethical, Legal & Practical Implications

• Patient autonomy: informed consent & right to refuse
• OSHA & Needlestick Safety Act: mandatory safety-engineered devices; immediate sharps disposal
• HIPAA: specimen labels & requisitions must protect PHI in public areas
• Accuracy vs. patient safety: never over-tourniquet or ‘dig’ for veins—risk of injury & erroneous labs outweighs a repeat stick
• Cultural competence: explain fasting in culturally relevant terms; accommodate language barriers

Quick Reference – Tube Summary (Mnemonic)

"Young Boys Really Should Give Lovely Gifts"

• Yellow – SPS / ACD
• Blue – Citrate
• Red – None
• SST (Tiger/Gold) – Clot Activator + Gel
• Green – Heparin
• Lavender – EDTA
• Gray – Oxalate/Fluoride

Practice Question (Critical Thinking)

Q: Patient is allergic to latex. What tourniquet alternative is acceptable?

• A: Use a non-latex (e.g., nitrile or rubber) single-use tourniquet or a BP cuff inflated just below diastolic pressure as a substitute.

End-of-Lesson Checklist

• [ ] Correct site & patient identified
• [ ] Tourniquet applied ≤60 s; released before needle removal
• [ ] Needle bevel up, correct gauge for vein size
• [ ] Followed exact Order of Draw; tubes inverted gently
• [ ] Specimens labeled bedside with two identifiers & MA initials
• [ ] Sharps disposed; patient bandaged; adverse reactions documented