Introduction to Phlebotomy

Phlebotomy - the practice of drawing blood from patients for laboratory testing, transfusions, or donations - is one of the most commonly performed clinical procedures in healthcare. Phlebotomists typically draw blood from 20 to 50 patients per shift in busy hospitals. Doing it safely and correctly requires technical precision, thorough knowledge of specimen handling, strict adherence to infection control practices, and excellent communication skills. A successful blood draw depends as much on how you interact with the patient as it does on your needle technique.

This comprehensive guide covers everything an entry-level phlebotomist needs to know to perform venipuncture safely and accurately on day one, based on Clinical and Laboratory Standards Institute (CLSI) guidelines and widely accepted clinical practice standards.

Anatomy of the Antecubital Fossa

The antecubital fossa (the inside of the elbow) is the primary venipuncture site because the veins there are typically large, accessible, and well-anchored. Understanding the anatomy helps you choose the safest vein.

Three Primary Veins

1. Median cubital vein - The preferred vein for venipuncture. It runs diagonally across the antecubital fossa, connecting the cephalic and basilic veins. It is usually large, well-anchored to surrounding tissue (which means it does not roll easily), and is not positioned near major nerves or arteries.

2. Cephalic vein - Located on the lateral (outer/thumb) side of the arm. It is a good second choice. It tends to roll more than the median cubital, so you need to anchor it firmly. It is generally safe because major nerves and arteries are not nearby.

3. Basilic vein - Located on the medial (inner/pinky) side of the arm. Use this as a last resort in the antecubital area because the brachial artery and median nerve run close to this vein. Accidental puncture of the artery or nerve can cause serious complications.

Alternative Sites

When no suitable antecubital vein is available:

• Dorsal hand veins - Veins on the back of the hand. Use a butterfly (winged infusion) needle. These veins are smaller and more painful to puncture, but they are often visible and accessible.
• Forearm veins - Veins on the anterior forearm can sometimes be used, though they tend to be deeper and less well-anchored.
• Never draw from - Do not draw from an arm with an IV line (results will be contaminated), an arm on the side of a mastectomy (risk of lymphedema), an AV fistula or graft used for dialysis (unless specifically authorized), or an area with burns, scarring, or hematoma.

Equipment and Supplies

Collection Systems

Two primary collection systems are used in phlebotomy:

Evacuated tube system (ETS) - The most common method. Consists of a double-pointed needle, a plastic tube holder, and evacuated (vacuum) collection tubes. The vacuum in the tube draws blood automatically when the tube is pushed onto the needle inside the holder.

Syringe system - Uses a needle attached to a syringe. The phlebotomist manually pulls back the plunger to draw blood, then transfers it to collection tubes. Used for fragile veins where the vacuum of the ETS might collapse the vein.

Butterfly (winged infusion) set - A small needle with flexible wings and tubing that connects to either an ETS holder or a syringe. Ideal for hand veins, pediatric draws, elderly patients with fragile veins, and difficult access situations.

Needle Gauges

• 21 gauge - Standard for most adult venipuncture. Good flow rate, minimal hemolysis.
• 22 gauge - Used for smaller veins or patients with fragile veins. Slightly higher risk of hemolysis.
• 23 gauge - Butterfly needle gauge for very small veins (hand veins, pediatric patients). Higher hemolysis risk.
• Lower gauge numbers = larger needle diameter. A 21-gauge needle is larger than a 23-gauge needle.

Collection Tubes and Their Additives

Evacuated tubes have color-coded stoppers that indicate the additive inside. Each additive serves a specific purpose:

Stopper Color	Additive	Purpose	Common Tests
Light blue	Sodium citrate	Anticoagulant for coagulation studies	PT, PTT, INR, fibrinogen
Red	None (or clot activator)	Allows blood to clot for serum tests	Metabolic panels, lipids, drug levels
Gold (SST)	Clot activator + gel separator	Serum separator	Chemistry, thyroid, hepatitis
Green	Lithium heparin or sodium heparin	Anticoagulant	STAT chemistry, ammonia, electrolytes
Lavender (purple)	EDTA	Anticoagulant, preserves cell morphology	CBC, hemoglobin A1c, blood type
Gray	Sodium fluoride + potassium oxalate	Glycolytic inhibitor	Glucose, blood alcohol
Yellow	SPS (sterile) or ACD	Bacterial growth medium or anticoagulant	Blood cultures, HLA typing
Royal blue	EDTA or none (trace element free)	Trace element testing	Lead levels, heavy metals
Pink	EDTA (spray-coated)	Blood bank anticoagulant	Blood type, crossmatch, antibody screen

Other Essential Supplies

• Tourniquet - Flat latex-free band. Single-use disposable tourniquets are preferred for infection control.
• Alcohol prep pads - 70% isopropyl alcohol for site disinfection.
• Povidone-iodine pads - Used for blood culture collection (or chlorhexidine per facility protocol).
• Gauze pads (2x2) - For post-draw pressure.
• Adhesive bandages or coban wrap - To secure gauze after the draw.
• Sharps container - For immediate needle disposal. Must be within arm's reach during the procedure.
• Gloves - A fresh pair for every patient. Non-latex options must be available.
• Labels - Pre-printed or handwritten with patient name, date of birth, date, time, and collector's initials.

The Order of Draw

When collecting multiple tubes, they must be drawn in a specific sequence to prevent cross-contamination of additives between tubes. Residual additive on the needle can transfer to the next tube and interfere with test results. The CLSI-recommended order of draw for the evacuated tube system is:

1. Blood cultures (yellow or dedicated blood culture bottles) - Must be collected first to minimize contamination risk
2. Coagulation tubes (light blue / sodium citrate) - Citrate contamination from other tubes would alter coagulation results. If a light blue tube is the only tube or the first tube (no blood culture needed), draw a discard tube first to clear tissue thromboplastin from the needle.
3. Serum tubes (red, gold SST) - No anticoagulant or clot activator with gel
4. Heparin tubes (green) - Heparin anticoagulant
5. EDTA tubes (lavender, pink) - EDTA is the strongest chelating agent; drawing it last prevents EDTA contamination of other tubes
6. Glycolytic inhibitor tubes (gray) - Oxalate/fluoride

Memory aid: "Boys Love Roses, Growing Lovely Gardens" - Blood cultures, Light blue, Red/Gold, Green, Lavender, Gray.

The order of draw is the same for syringe draws and butterfly sets. For syringe draws, transfer blood into tubes in the same order.

Patient Identification and Communication

Two-Patient Identifier Protocol

Proper patient identification is a critical safety requirement established by The Joint Commission. Before any blood draw:

1. Ask the patient to state their full legal name
2. Ask the patient to state their date of birth
3. Compare both identifiers to the requisition form
4. Compare to the patient's wristband (inpatient settings)
5. Do not draw blood from any patient you cannot positively identify using two independent identifiers

Never identify a patient by asking "Are you John Smith?" The patient may be confused, hard of hearing, or simply agree. Always use open-ended questions: "Can you tell me your full name?"

Patient Communication

Good communication reduces anxiety, increases cooperation, and leads to better outcomes:

• Introduce yourself by name and role: "Good morning, my name is [name] and I am a phlebotomist from the laboratory."
• Explain the procedure briefly: "I need to draw some blood for tests that your doctor ordered."
• Ask about previous experiences: "Have you had any problems with blood draws in the past?"
• Ask about allergies to latex, adhesive tape, or iodine
• Let the patient know when you are about to insert the needle: "You will feel a small stick now."
• If the patient is anxious, reassure them and give them a moment. Suggest they look away.
• Never tell a patient "this won't hurt." Be honest: "You will feel a brief pinch."

Informed Consent and Right to Refuse

Patients have the right to refuse a blood draw. If a patient refuses:

1. Explain why the test was ordered and that the physician requested it
2. Do not force or threaten the patient
3. Document the refusal and notify the ordering physician or nurse
4. Follow your facility's refusal protocol

Performing the Venipuncture

Pre-Procedure Checklist

Before approaching the patient, verify:

• [ ] Requisition form matches patient identification
• [ ] You have all required tubes and supplies
• [ ] You understand any special collection requirements (fasting, timed draw, chilled specimen)
• [ ] Gloves are on
• [ ] Sharps container is accessible

Step-by-Step Procedure

1. Position the patient - The patient should be seated in a phlebotomy chair with an armrest, or lying in bed with the arm supported. Never draw blood from a standing patient (risk of syncope and fall). Extend the arm with a slight downward angle.

2. Apply the tourniquet - Place it 3 to 4 inches (about one hand-width) above the intended puncture site. The tourniquet should be tight enough to restrict venous blood flow but not so tight that it occludes arterial flow. You should still feel a radial pulse. Ask the patient to make a gentle fist (do not pump the fist, as this can alter potassium levels).

3. Select the vein - Palpate with your index finger. A good vein feels spongy, bouncy, and resilient. It refills when you press and release. An artery will feel like it is pulsing. A tendon feels hard, cord-like, and does not bounce. Do not select a vein that feels hard or cord-like (may be scarred or thrombosed).

4. Release the tourniquet while you prepare your equipment if more than one minute will pass. Prolonged tourniquet application (over 1 minute) can alter lab results by concentrating blood components (hemoconcentration).

5. Clean the site - Scrub the puncture site with a 70% isopropyl alcohol prep pad using a firm, circular motion from the center outward. Allow the site to air dry completely (approximately 30 seconds). Do not blow on it, fan it, or touch it after cleaning.

6. Reapply the tourniquet - If you released it during preparation.

7. Anchor the vein - With your non-dominant hand, use your thumb to pull the skin taut 1 to 2 inches below the puncture site. This anchors the vein and prevents it from rolling.

8. Insert the needle - With the bevel (the angled opening) facing up, insert the needle at a 15 to 30 degree angle in the direction of blood flow (toward the hand). Use a smooth, controlled motion. You will feel a slight "pop" or "give" when the needle enters the vein.

9. Engage the first tube - Push the collection tube onto the needle inside the holder. The vacuum will draw blood into the tube. Hold the holder steady - do not push or pull on the needle.

10. Fill tubes in the correct order - When the first tube stops filling, remove it with a gentle twist and push the next tube on. Gently invert tubes with additives (not those without) 5 to 10 times immediately upon removal to mix the additive with the blood. Do not shake.

11. Release the tourniquet - Always release the tourniquet before removing the needle. Removing the needle with the tourniquet in place increases the risk of hematoma.

12. Remove the needle - Place a folded gauze pad over the puncture site (without pressing yet), then withdraw the needle smoothly at the same angle it was inserted. Immediately activate the needle's safety device.

13. Apply pressure - Press the gauze firmly over the site. Ask the patient to hold pressure for 2 to 3 minutes (5 minutes for patients on anticoagulants or aspirin). Do not let the patient bend their arm - this is a common mistake that increases hematoma formation.

14. Dispose of the needle - Immediately place the needle and holder in the sharps container. Never recap a needle.

15. Label tubes at the bedside - Label every tube while still with the patient. Each label must include the patient's full name, date of birth, medical record number (if applicable), date and time of collection, and your initials. Never pre-label tubes before the draw.

16. Check the patient - Remove the gauze and inspect the site. Apply an adhesive bandage. Ask the patient how they feel before allowing them to leave.

Specimen Handling and Transport

General Handling Rules

• Transport specimens to the lab promptly - Many tests are time-sensitive. Glucose decreases approximately 5-7% per hour at room temperature in tubes without glycolytic inhibitors.
• Keep specimens at the required temperature - Most specimens are transported at room temperature. Some require special handling:
  • Cold agglutinins, cryoglobulin, and cryofibrinogen must be kept warm (37 degrees C)
  • Ammonia, lactic acid, and arterial blood gases must be transported on ice
  • Bilirubin samples must be protected from light (wrap in foil)
• Gentle handling - Never shake tubes. Pneumatic tube systems can cause hemolysis if not properly padded.
• Centrifuge timing - Serum tubes need 30 minutes to clot before centrifugation. EDTA and heparin tubes can be centrifuged immediately.
• Specimen rejection criteria - Labs will reject specimens that are hemolyzed, clotted (when they should not be), under-filled (especially light blue tops, which must be filled to the line for proper blood-to-anticoagulant ratio), mislabeled, or collected in the wrong tube type.

Blood Culture Collection

Blood cultures require extra care to prevent contamination:

1. Clean the site with chlorhexidine or povidone-iodine (per facility protocol) and allow it to dry completely
2. Clean the tops of the blood culture bottles with alcohol
3. Do not palpate the cleaned site
4. Collect the aerobic bottle first, then the anaerobic bottle
5. Fill each bottle with 8-10 mL of blood for adults
6. If two sets are ordered from different sites, label each set with the site of collection
7. Blood cultures contaminated with skin flora lead to unnecessary antibiotic treatment and increased hospital costs

Common Complications and How to Handle Them

Hematoma

A bruise caused by blood leaking into the surrounding tissue. Causes include: through-and-through puncture of the vein, needle bevel only partially in the vein, excessive probing, removing the needle before releasing the tourniquet, or insufficient pressure after the draw. If you see swelling during the draw, immediately release the tourniquet, remove the needle, and apply firm pressure for 5 minutes.

Hemolysis

The rupture of red blood cells, causing serum or plasma to turn pink or red. This invalidates many test results. Causes include: using too small a needle, pulling a syringe plunger back too forcefully, shaking tubes instead of gently inverting, forcing blood through a small needle into a tube, or drawing from a hematoma. Prevention: use the largest appropriate gauge needle, use gentle technique, and invert tubes slowly.

Nerve Injury

If the patient reports sharp, shooting, electrical, or radiating pain at any point during the procedure, remove the needle immediately. This may indicate you have contacted a nerve. Do not redirect the needle. Apologize, apply pressure, and attempt the draw at a different site. Document the incident per your facility's policy.

Syncope (Fainting)

Some patients faint during or after blood draws. Warning signs include pallor, sweating, lightheadedness, nausea, and tunnel vision.

• If the patient is in a chair, lower the head between the knees or recline the chair
• If the patient loses consciousness, lower them to the floor safely, elevate their legs, and loosen tight clothing
• Apply a cold compress to the forehead or back of the neck
• Never leave a patient who reports feeling faint unattended
• Some facilities require a post-draw observation period for patients who have a history of syncope

Petechiae

Small red dots that appear after prolonged tourniquet application. Prevent by limiting tourniquet time to one minute. If petechiae develop, release the tourniquet immediately.

Failure to Obtain Blood

If blood does not flow into the tube:

1. Make sure the tube has vacuum - try a new tube
2. Gently rotate the needle a quarter turn (the bevel may be against the vein wall)
3. Pull back slightly (you may have gone through the vein)
4. Advance slightly (you may not be fully in the vein)
5. If still unsuccessful, remove the needle and try a different site
6. Do not probe or redirect more than twice on a single insertion. Limit total attempts to two per phlebotomist. If unsuccessful after two attempts, ask a colleague or supervisor for help.

Infection Control

Standard Precautions

Standard precautions apply to every patient, every time:

• Wear gloves for all blood draws. Change gloves between patients.
• Perform hand hygiene before and after every patient contact, even when wearing gloves
• Dispose of sharps immediately in a puncture-resistant sharps container
• Clean any blood spills with an approved disinfectant
• Never recap needles by hand

Needlestick Injuries

If you sustain a needlestick injury:

1. Immediately wash the area with soap and water (for mucous membrane exposure, flush with water)
2. Report the injury to your supervisor immediately
3. Go to employee health or the emergency department for evaluation
4. Identify the source patient if possible (their blood may need to be tested)
5. Follow your facility's bloodborne pathogen exposure protocol
6. You may be offered post-exposure prophylaxis (PEP) depending on the source patient's status

The most significant bloodborne pathogens transmitted through needlestick injuries are HIV, Hepatitis B, and Hepatitis C. Vaccination against Hepatitis B is required for healthcare workers.

Special Populations

Pediatric Patients

• Use butterfly needles and smaller collection tubes (microtainers) for infants
• Capillary (heel stick or finger stick) collection is preferred for infants under 6 months
• For heel sticks, warm the heel for 3-5 minutes, puncture the medial or lateral plantar surface (not the center, to avoid bone), and use a lancet with a depth appropriate for the infant's size
• Have a parent or assistant help hold the child. Distraction techniques (singing, bubbles, tablets) can help.
• Collect only the minimum volume needed for testing

Geriatric Patients

• Veins are often fragile, thin-walled, and prone to rolling
• Use a smaller gauge needle (22 or 23) or a butterfly
• Apply the tourniquet loosely to avoid tearing fragile skin
• Anchor the vein very firmly as rolling veins are common
• Apply pressure for longer after the draw as bruising is more likely
• Be patient and communicate clearly, as hearing or cognitive impairment may be present

Patients on Anticoagulants

• Patients taking warfarin, heparin, aspirin, or newer anticoagulants (apixaban, rivarcloxaban) bleed longer
• Apply pressure for at least 5 minutes after the draw
• Do not use adhesive bandages alone - use gauze with a pressure wrap
• Document the anticoagulant use

Key Takeaways

• Always verify patient identity with two independent identifiers before any blood draw
• Follow the order of draw to prevent cross-contamination of tube additives
• The median cubital vein is the safest and most reliable site in the antecubital fossa
• Never redirect a needle if the patient reports sharp or shooting pain
• Label all specimens at the bedside immediately after collection
• Limit tourniquet time to one minute to prevent hemoconcentration and petechiae
• Apply pressure for 2 to 3 minutes (5 minutes for patients on blood thinners) and do not allow arm bending
• Transport specimens promptly and handle them gently to prevent hemolysis
• Dispose of all sharps immediately and never recap needles
• If you cannot obtain blood after two attempts, ask for help