3.6 Phlebotomy
Key Takeaways
The order of draw for vacuum tubes is: blood cultures (yellow), light blue (coagulation), red (no additive), gold/SST (serum separator), green (heparin), lavender/purple (EDTA), gray (oxalate/fluoride)
The median cubital vein in the antecubital fossa is the preferred venipuncture site; the cephalic and basilic veins are alternatives
A tourniquet should not remain on the arm for more than 1 minute to prevent hemoconcentration and inaccurate results
Venipuncture complications include hematoma, nerve injury, syncope (fainting), infection, and hemolysis of the specimen
Capillary puncture (dermal puncture) is used for infants, elderly patients with fragile veins, and when only small amounts of blood are needed
Specimens must be labeled at the bedside/chairside immediately after collection with patient name, DOB, date/time, collector initials, and test ordered
Phlebotomy (blood collection) is a core clinical skill for medical assistants. The CCMA exam tests your knowledge of venipuncture technique, order of draw, site selection, specimen handling, and complication management.
Venipuncture Equipment
| Equipment | Purpose |
|---|---|
| Evacuated tubes (Vacutainer) | Collect blood into color-coded tubes with specific additives |
| Multi-sample needle | Allows collection of multiple tubes from one venipuncture |
| Tube holder/adapter | Holds the needle and tube during collection |
| Tourniquet | Restricts venous blood flow to engorge veins |
| Alcohol prep pad | Cleans the puncture site (70% isopropyl alcohol) |
| Gauze pads | Apply pressure after needle removal |
| Bandage/tape | Cover the puncture site post-procedure |
| Needle disposal | Sharps container for used needles |
| Butterfly (winged infusion) set | Used for difficult veins, hand veins, and pediatric patients |
| Syringe | Alternative for fragile veins; prevents vacuum from collapsing the vein |
Order of Draw (Evacuated Tube System)
The order of draw prevents cross-contamination of additives between tubes:
| Order | Tube Color | Additive | Common Tests |
|---|---|---|---|
| 1 | Yellow (SPS) or blood culture bottles | SPS or none | Blood cultures (aerobic first, then anaerobic) |
| 2 | Light blue | Sodium citrate | Coagulation studies (PT/INR, PTT, D-dimer) |
| 3 | Red | None (no additive) | Blood bank, serology, some chemistry |
| 4 | Gold/red-gray (SST) | Clot activator + gel separator | Chemistry panels, thyroid, lipids |
| 5 | Green | Lithium heparin or sodium heparin | STAT chemistry, ammonia |
| 6 | Lavender/purple (EDTA) | EDTA | CBC, hemoglobin A1C, ESR, blood typing |
| 7 | Gray | Potassium oxalate + sodium fluoride | Glucose, blood alcohol |
Memory Aid for Order of Draw: "Stop Light Red, Go Low Gray" or "Boys Love Red Gold, Girls Love Gray"
- Blood cultures → Light blue → Red → Gold → Green → Lavender → Gray
Why order matters:
- Light blue tubes MUST be the first additive tube (or second if blood cultures are drawn) because citrate contamination from other tubes affects coagulation results
- EDTA contamination (lavender tube) can falsely elevate potassium levels if it gets into chemistry tubes
Venipuncture Site Selection
Preferred site: Median cubital vein — located in the antecubital fossa (inner elbow area)
- Largest, most stable vein
- Closest to the surface
- Least painful
- Least likely to cause complications
Alternative sites (if median cubital is unavailable):
- Cephalic vein — lateral (thumb) side of the antecubital fossa
- Basilic vein — medial (pinky) side; closest to brachial artery and median nerve — higher risk of injury
Sites to AVOID:
- Arms with IV infusions (results will be diluted/contaminated)
- Arm on the side of a mastectomy (lymphedema risk)
- Scarred or burned areas
- Arms with AV fistulas or grafts (dialysis patients)
- Edematous (swollen) areas
- Areas with hematomas from previous attempts
Venipuncture Procedure
- Verify the order and identify the patient (two identifiers)
- Assemble equipment; check tube expiration dates
- Explain the procedure to the patient; obtain consent
- Position the patient's arm extended and supported, palm up
- Apply the tourniquet 3-4 inches above the intended puncture site
- Select the vein by palpation (feel for a spongy, bouncy vessel)
- Clean the site with 70% alcohol in a circular motion; allow to air dry
- Anchor the vein by pulling the skin taut below the puncture site
- Insert the needle at a 15-30 degree angle, bevel up
- Collect tubes in the correct order of draw; invert additive tubes gently
- Release the tourniquet BEFORE removing the needle (within 1 minute of application)
- Remove the needle; apply gauze with pressure
- Activate the needle safety device; dispose in sharps container
- Label tubes at the bedside/chairside immediately
- Apply bandage after bleeding stops (2-5 minutes of pressure)
Tourniquet Rules:
- Apply 3-4 inches above the site
- Do NOT leave on for more than 1 minute (causes hemoconcentration, falsely elevated results)
- Release the tourniquet BEFORE removing the needle to prevent hematoma
- If a vein is not found within 1 minute, release for 2 minutes before reapplying
Capillary (Dermal) Puncture
Used when venipuncture is not feasible or for small-volume tests:
Indications:
- Infants and neonates (heel stick)
- Elderly patients with fragile veins
- Patients with burns or severe scarring on arms
- When small blood volume is sufficient (glucose, hemoglobin)
- Home monitoring (e.g., glucose self-testing)
Puncture Sites:
- Adults/children: Lateral sides of fingertips (ring or middle finger preferred)
- Infants (<12 months): Lateral or medial plantar surface of the heel (NEVER the arch or center)
Capillary Puncture Order of Draw:
- EDTA tubes (lavender microcontainer) — to prevent platelet clumping
- Other additive tubes
- Non-additive tubes (red microcontainer)
Note: The order of draw for capillary puncture differs from venipuncture because EDTA tubes are collected FIRST.
Phlebotomy Complications
| Complication | Cause | Prevention/Response |
|---|---|---|
| Hematoma | Blood leaking into tissue around the vein | Apply firm pressure for 2-5 minutes; release tourniquet before removing needle |
| Syncope (fainting) | Vasovagal response | Observe patient for signs; lower head; have ammonia inhalant available |
| Nerve injury | Needle contacts a nerve | Immediately withdraw if patient reports sharp, shooting pain; do NOT probe |
| Hemolysis | RBCs rupture, releasing hemoglobin | Use correct gauge needle; avoid fist pumping; gently invert tubes |
| Hemoconcentration | Tourniquet left on too long (>1 min) | Release tourniquet within 1 minute |
| Infection | Non-sterile technique | Proper skin antisepsis; do not palpate after cleaning |
| Petechiae | Tourniquet too tight | Adjust tourniquet pressure |
| Collapsed vein | Too much vacuum (fragile vein) | Use butterfly or syringe technique for fragile veins |
If unsuccessful after 2 attempts: Stop and have another qualified phlebotomist try. Never make more than 2 attempts on one patient.
What is the CORRECT order of draw for evacuated tubes?
Lavender → light blue → red → gold → green → gray
Red → light blue → gold → green → lavender → gray
Blood cultures → light blue → red → gold → green → lavender → gray
Light blue → blood cultures → red → green → gold → lavender → gray
The PREFERRED vein for routine venipuncture is the:
Basilic vein
Cephalic vein
Median cubital vein
Dorsal hand vein
How long can a tourniquet remain on the patient's arm during venipuncture?
30 seconds
1 minute
3 minutes
5 minutes
When performing a capillary puncture on an infant, the correct site is the:
Fingertip (ring finger)
Arch of the foot
Lateral or medial plantar surface of the heel
Center of the heel pad
Arrange the venipuncture steps in the correct order.
Arrange the items in the correct order
Label tubes at the bedside immediately
Insert the needle at 15-30 degrees, bevel up
Verify the order and identify the patient
Apply tourniquet 3-4 inches above the site
Clean the site with alcohol and allow to air dry
Release the tourniquet before removing the needle
Sections you finish are checked off in the contents.