6.1 Phlebotomy Terminology and Equipment
Key Takeaways
- CLSI PRE02, Collection of diagnostic venous blood specimens, 8th edition (2025), is the current venous-collection standard and the successor to GP41.
- Petechiae are pinpoint capillary hemorrhages, often from a tight or prolonged tourniquet; a hematoma is a raised collection of blood in tissue after vessel leakage.
- An adapter (tube holder) seats an evacuated tube on a double-ended needle; a transfer device moves syringe blood into tubes without exposing a sharp.
- A butterfly (winged infusion set) is for small, fragile, or difficult veins; a syringe is for veins that would collapse under evacuated-tube vacuum.
- Pulse at a proposed puncture site indicates an artery; routine CMLA collections are venous or capillary, not arterial.
CMLA Work Area II (Preexamination / Preanalytical Considerations) is 36 items, or 18.0% of the 200-question exam. Phlebotomy is competency 3. Before vein selection, order of draw, or hemolysis (Chapter 7), you must define the tools and patient events AMT lists under II.3.A.1: tourniquet, lancet, safety needle, evacuated tube, adapter, syringe, butterfly, safety lancet, hematoma, petechiae, pulse, syncope, seizure, vein/venous, capillary, artery/arterial, serum, plasma, whole blood, anticoagulant, preservative, and transfer device.
The current Clinical and Laboratory Standards Institute (CLSI) document for venous collection is CLSI PRE02, Collection of diagnostic venous blood specimens, 8th edition (2025). PRE02 succeeds the older GP41 guideline. AMT CMLA-REF-2025-1 also lists the PRE02 quick guide (PRE02QG) and, for identification, CLSI PRE01. Capillary collection remains GP42; handling and transport is PRE04. If a stem asks for the current venous-collection standard, the answer is PRE02, not GP41.
Quick Answer: Name each device by its job. An adapter holds an evacuated tube on a double-ended needle; a transfer device moves syringe blood into tubes. A butterfly is for small or difficult veins; a syringe is for veins that collapse under vacuum. Petechiae are pinpoint spots; a hematoma is a raised leak. Pulse at the site means artery, not a strong vein.
Evacuated-tube system: tube, adapter, and safety needle
An evacuated tube is a sterile, closed collection tube manufactured with a measured vacuum so it fills to a predetermined volume when the stopper is pierced. Color-coded stoppers identify the additive (or the absence of one). The vacuum is a design feature, not a guarantee: an expired, cracked, or previously opened tube can lose vacuum and underfill. Underfilled additive tubes change the blood-to-additive ratio; that integrity problem is expanded in Chapter 7.
An adapter (tube holder or hub) is the barrel that seats the evacuated tube against a double-ended needle. One end of the needle enters the vein; the sheathed back end punctures the tube stopper. Do not strip the back-end sleeve off to make the tube fill faster. The adapter is single-patient equipment. It is not a tourniquet, and it is not a transfer device.
A safety needle is a venipuncture needle with engineered sharps-injury protection (retractable cannula or hinged shield). OSHA's Bloodborne Pathogens Standard (29 CFR 1910.1030) and the Needlestick Safety and Prevention Act require safer devices when they are available and effective. Activate the safety feature immediately after the needle leaves the patient, then discard needle and adapter as a unit into a puncture-resistant sharps container. Walking with an unshielded used needle, or using a non-safety needle when a safety device is in the drawer, is the terminology failure applied.
Syringe, butterfly, and transfer device
A syringe is a barrel-and-plunger device used when vacuum might collapse a small or fragile vein, when fill rate must be controlled by hand, or when an evacuated-tube assembly cannot be used. Blood in a syringe is still a specimen. You never two-hand recap, and you never push an exposed needle through a tube stopper to fill tubes.
A transfer device (blood-transfer device) is a needleless or sheathed adapter that lets you fill evacuated tubes from a syringe without exposing a sharp. CLSI PRE02 and OSHA expect this device whenever syringe blood is moved into tubes. Forcing blood in with the plunger overpressurizes the tube, hemolyzes cells, and defeats the vacuum. The transfer device and the evacuated-tube adapter look similar in a supply bin; they are not interchangeable names on CMLA.
A butterfly (winged infusion set) is a short needle with flexible tubing and plastic wings. Use it for small or difficult veins (dorsal hand, pediatrics, oncology, scarred antecubital veins) when you need finer control of angle and depth, or when the patient cannot tolerate a standard straight needle. A butterfly can attach to an adapter for evacuated tubes or to a syringe. It is not the default for every healthy adult antecubital draw. Extra tubing increases the chance of underfilled coagulation tubes (air in the line occupies volume) and of needlesticks if the safety feature is not activated. The CMLA trap is butterfly versus syringe: choose a butterfly for control on a small vein; choose a syringe when vacuum would collapse the vein. Neither device replaces a transfer device after a syringe fill.
| Device | What it is | Typical CMLA use | Classic trap |
|---|---|---|---|
| Evacuated tube plus adapter | Vacuum tube seated in a holder | Routine venous draws | Expired or under-vacuum tube; calling the holder a transfer device |
| Safety needle | Needle with engineered shield or retraction | Every venipuncture when available | Walking with an unshielded used needle |
| Butterfly (winged set) | Short needle, tubing, wings | Small, fragile, or hand veins; finer control | Using it for every adult draw; underfilling citrate tubes |
| Syringe | Plunger-controlled draw | Veins that collapse under vacuum | Recapping or needle-puncturing a tube stopper |
| Transfer device | Needleless or sheathed syringe-to-tube adapter | Moving syringe blood into tubes | Pushing the plunger to speed fill |
Lancet and safety lancet
A lancet is a capillary-puncture device that makes a controlled skin incision for fingerstick or heelstick collection. A safety lancet is a single-use lancet whose blade or needle retracts permanently so it cannot be reused and cannot stay exposed. OSHA treats used lancets as contaminated sharps. Depth is selected by choosing the correct device, not by guessing how hard to press: adult fingerstick devices and infant heel devices are not interchangeable. Full capillary technique, including infants, belongs in Chapter 8; here you need the names, the single-use rule, and the fact that a safety lancet is not a venipuncture safety needle.
Tourniquet
A tourniquet is a band applied around the arm to slow venous return so veins fill and become visible or palpable. It is a venous-distention tool, not an arterial clamp and not a standing order to leave the arm purple. Apply it 3–4 inches above the site. CLSI venous-collection practice limits tourniquet time (classically about one minute) because longer application concentrates cells and proteins (hemoconcentration) and can produce petechiae. Release it once blood flow is established. A tourniquet tight enough to abolish the distal pulse is too tight. Leaving it on while you walk away to find tubes is both a quality error and a patient-safety error.
Vein, capillary, artery, and pulse
A vein (venous blood) carries blood toward the heart. Superficial veins of the antecubital fossa (median cubital, cephalic, basilic) and dorsal hand veins are the routine phlebotomy targets. Veins do not pulsate. Palpate for a bouncy, resilient cord, not for a beat.
A capillary is the microscopic vessel between arterioles and venules. Capillary blood is a mixture of arterial blood, venous blood, and interstitial fluid. Fingerstick and heelstick specimens are capillary, not venous. Do not report a fingerstick as a venipuncture specimen.
An artery (arterial blood) carries blood away from the heart and pulses. Pulse is the palpable arterial expansion with each heartbeat. Feeling a pulse at a proposed puncture site means you are on or next to an artery, not a strong vein. Routine CMLA collections are venous or capillary. Arterial puncture for blood gases is a specialized procedure outside ordinary assistant venipuncture. If bright-red blood pulses into the tube or a hematoma expands rapidly, treat it as possible arterial involvement: remove the needle, apply firm prolonged pressure per policy, and do not relabel the event as a normal venous draw.
Hematoma, petechiae, syncope, and seizure
A hematoma is a raised collection of blood in the tissue after leakage from a vessel. Causes include going through the vein, failing to apply pressure after withdrawal, probing, or puncturing an artery. It looks and feels like a swelling bruise forming under the skin.
Petechiae are pinpoint, non-raised red or purple spots from capillary leakage. A tight or prolonged tourniquet, thrombocytopenia, or fragile capillaries can produce them. Petechiae are not miniature hematomas. On CMLA this pair is a designed trap: hematoma = pooled blood in tissue; petechiae = pinpoint capillary hemorrhages, often on the forearm below a tourniquet.
Syncope is fainting—transient loss of consciousness from decreased cerebral blood flow. Warning signs include dizziness, nausea, sweating, pallor, or a sudden feeling of warmth. If syncope begins, remove the needle, protect the patient from a fall (lower the head, do not prop an unconscious patient on the chair edge), and follow facility first-aid policy. Do not keep filling tubes while the patient is losing consciousness.
A seizure is abnormal electrical brain activity with involuntary movement or altered awareness. Remove the needle immediately, do not restrain the limbs, clear nearby objects, and call for help. Do not put anything in the mouth. Document and report. Do not finish the draw during a seizure.
Serum, plasma, whole blood, anticoagulant, and preservative (names)
Whole blood is blood as drawn, with cells still suspended in the liquid. Plasma is the liquid portion of anticoagulated blood. Serum is the liquid left after blood has clotted. An anticoagulant prevents clotting (EDTA, citrate, heparin, oxalate). A preservative protects an analyte after collection; sodium fluoride as a glycolytic inhibitor, usually paired with an oxalate anticoagulant in a gray-top tube, is the classic example. Section 6.2 is the chemistry of these five words. II.3.A.1 only requires that you not treat serum and plasma as synonyms and not call every additive an anticoagulant.
Exam traps
- Petechiae are not small hematomas; hematomas are not petechiae.
- A butterfly is not automatically better than a straight safety needle; a syringe is not a substitute for a transfer device.
- Pulse at the site means artery, not a strong vein.
- PRE02 (2025), not GP41, is the current venous-collection standard; PRE01 is identification; GP42 is capillary.
- An adapter holds the tube; a transfer device moves syringe blood. They are not the same part.
- A safety lancet is a capillary device; a safety needle is a venipuncture device.
When CMLA shows a device or a complication word, define it in one sentence, name when you would choose it, and name the look-alike it is not.
During a venous draw the forearm below the tourniquet shows pinpoint, non-raised red spots, and a raised swelling later forms at the puncture after the needle went through the vein. Which statement correctly names those findings?
When is a winged infusion set (butterfly) the better choice than a syringe for a CMLA collection?
Which statement correctly identifies the current CLSI standard for collection of diagnostic venous blood specimens?