While routine venipuncture covers the majority of your workload, a skilled phlebotomist must be prepared for “the difficult draw.” Lesson 5 focuses on specialized procedures and how to adapt your technique for patients who require extra care.

1. Capillary (Dermal) Punctures

When a vein is inaccessible or only a minute amount of blood is needed, a skin puncture is performed. This is common for point-of-care testing (like glucose) or pediatric patients.

• Sites: * Adults/Children (>1 year): The fleshy side of the middle or ring finger (non-dominant hand). Puncture across the fingerprint lines.

  • Infants (<1 year): The medial or lateral portions of the plantar surface of the heel. Never the center of the heel to avoid bone injury (osteomyelitis).

• The “First Drop” Rule: Always wipe away the first drop of blood with gauze. The first drop contains interstitial fluid and tissue debris that can contaminate the sample.

• Order of Draw (Capillary): This is different from venipuncture!

  1. EDTA (Lavender)

  2. Other Additives (Green/Gray)

  3. Serum (Red/Gold)

2. Blood Cultures (Sepsis Detection)

Blood cultures are used to detect microorganisms in the blood. Because any skin bacteria can ruin the test, the process is rigorous.

• Site Prep: Requires “surgical” cleanliness. Use Chlorhexidine or a two-step alcohol-iodine scrub for 30–60 seconds.

• Volume: Crucial for accuracy. Usually, 8–10 mL per bottle for adults.

• The Set: Always collect an Aerobic (with air) and an Anaerobic (without air) bottle.

  • Tip: If using a butterfly needle, draw the Aerobic bottle first so the air in the tubing doesn’t enter the Anaerobic bottle.

3. Therapeutic Drug Monitoring (TDM)

Some medications have a narrow “therapeutic window”—too little is ineffective, too much is toxic.

• Trough Level: Collected when the drug is at its lowest level in the body, usually 30 minutes before the next dose.

• Peak Level: Collected when the drug is at its highest level. The timing varies based on how the drug was administered (IV vs. Oral).

4. Challenging Populations: Geriatric & Pediatric

The approach must change based on the patient’s age and physical condition.

Geriatric (Elderly) Patients

• Physical Changes: Veins lose elasticity (become “fragile”) and may roll easily. Skin is thinner and prone to tearing.

• Technique: Use a smaller gauge needle or a butterfly. Apply the tourniquet over clothing or a thin sleeve to protect the skin. Use less tension when anchoring.

Pediatric (Children) Patients

• Psychological Prep: Never lie and say “it won’t hurt.” Use words like “a small pinch.”

• Physical Control: Ask a parent or another tech to help stabilize the arm. Distraction is your best tool.

• Equipment: Use butterfly sets and smaller collection tubes to prevent collapsing their tiny veins.

5. Managing Complications & Refusals

• Mastectomy: Never draw blood from the arm on the same side as a mastectomy (due to lymphostasis). If both sides are affected, consult a physician.

• IV Sites: Ideally, avoid the arm with an IV. If necessary, draw below the IV site and have the nurse turn off the IV for 2 minutes prior to the draw.

• Patient Refusal: Patients have the right to refuse. Never argue or force the procedure. Document the refusal and notify the nursing staff or physician.

6. Special Handling Requirements

Some tests are sensitive to the environment:

• Chilled Specimens: (e.g., Ammonia, Lactic Acid) Must be placed in an ice-water slurry immediately.

• Light-Sensitive: (e.g., Bilirubin, Vitamin B12) Must be wrapped in aluminum foil or placed in amber tubes.

• Warmed: (e.g., Cold Agglutinins) Must be kept at 37°C in a heat block.