Quick facts
- A butterfly needle, or winged infusion set, is a short thin needle with plastic wings and a length of flexible tubing between the needle and the connector. The tubing is the reason it exists: the collector can angle the needle without fighting a rigid hub.
- United States: a hypodermic single lumen needle is a Class II device under 21 CFR 880.5570, defined as a device intended to inject fluids into, or withdraw fluids from, parts of the body below the surface of the skin.
- Canada: the same needle is a Class II medical device, and a Class II device needs a device licence applied for under section 32 of the Medical Devices Regulations.
- Ontario adds a workplace duty the US rulebook does not. Under O. Reg. 474/07, when a worker is to do work requiring the use of a hollow-bore needle, the employer shall provide the worker with a safety-engineered needle that is appropriate for the work.
- In the United States the parallel duty sits in OSHA's bloodborne pathogens standard, which requires engineering controls and lists sharps with engineered sharps injury protections among them.
A butterfly needle is a needle on flexible wings and tubing, and it is the device a draw station reaches for when a vein is small, fragile or awkward to reach. Gauge selection looks like a clinical preference, but it is also a purchasing decision: the wrong gauge in stock means either a failed draw or an unnecessary puncture, and the safety features built into the set are a legal requirement in some jurisdictions and a work practice in others. Canada and the United States regulate the needle and the hazard around it differently, and both differences land on the same shelf.
What is a butterfly needle, and when is it used instead of a straight needle?
The set has four parts: the needle, two wings, a length of small-bore tubing, and a connector that mates with a syringe, a tube holder or an administration set reserve.
The wings matter more than they look. They give the collector a grip close to the puncture site, which allows a shallower angle and finer control than a straight needle with a rigid hub. The tubing absorbs movement, so a patient who flinches does not translate that movement straight into the vein wall.
The regulator's definition of the underlying device is deliberately plain. The US classification describes a hypodermic single lumen needle as "a device intended to inject fluids into, or withdraw fluids from, parts of the body below the surface of the skin," consisting of a metal tube sharpened at one end and joined at the other to a hub designed to mate with the nozzle of a piston syringe or an intravascular administration set. A winged set is that device with a grip and tubing added.
| Situation | Winged set | Straight needle |
|---|---|---|
| Small or fragile veins | Usual choice | Difficult |
| Hand or foot veins | Usual choice | Awkward |
| Paediatric draws | Usual choice | Possible with a skilled collector |
| Large antecubital vein, routine draw | Workable | Usual choice |
| Multiple tubes from one puncture | Workable, with a holder | Usual choice |
| Agitated or moving patient | Reduces movement transfer | Movement transfers directly |
Where the two overlap, the deciding factor is usually the collector's assessment on the day rather than a rule.
Which gauge should a draw station stock?
Gauge is a number that runs backwards: the larger the number, the smaller the bore. That single fact explains most ordering mistakes, because a 25G set looks like a "bigger" item on a purchase order than a 21G set.
| Gauge band | Bore character | Typical situation | Practical note |
|---|---|---|---|
| 21G | Wider bore | Routine draws, faster fill | More comfortable for some high-volume draws |
| 23G | Mid range | Fragile or small veins, most clinic work | The common stock item in many clinics |
| 25G | Fine bore | Very small or superficial veins | Slower fill; haemolysis risk rises with force |
| 27G and finer | Very fine | Specialised uses | Not a general draw-station item |
Two ordering habits keep a station covered. First, stock one mid-range gauge as the default and one finer gauge for the fragile-vein case, rather than three half-used boxes. Second, keep the needle gauge and the intended tube together in the collector's mind: a fine-bore set pushing into a vacuum tube draws slowly, and forcing it is how a haemolysed specimen happens.
Is a winged infusion set regulated the same way in Canada and the US?
The device is the same idea in both countries, but the market pathway and the workplace duty are not.
In the United States, the needle sits in 21 CFR 880.5570 as a Class II device with performance standards, and the public record of cleared products is the premarket notification database. In Canada, a needle is a Class II medical device under the Medical Devices Regulations, and the pathway is a device licence applied for under section 32, in contrast to a Class I device, which reaches the market through an establishment licence under section 45.
The sharper difference is the safety feature. Ontario's needle safety regulation defines a safety-engineered needle as either a hollow-bore needle designed to eliminate or minimize the risk of a skin puncture injury to the worker, or a needleless device that replaces a hollow-bore needle, and adds a market condition to that definition. Its operative provision is a duty on the employer: when a worker is to do work requiring the use of a hollow-bore needle, the employer shall provide the worker with a safety-engineered needle that is appropriate for the work.
In the United States the same protection is framed as hazard control rather than product definition. OSHA's bloodborne pathogens standard defines engineering controls as controls, "e.g., sharps disposal containers, self-sheathing needles, safer medical devices, such as sharps with engineered sharps injury protections and needleless systems", that isolate or remove the bloodborne pathogens hazard from the workplace, and it defines "sharps with engineered sharps injury protections" as a needle device used for withdrawing body fluids, accessing a vein or artery, or administering medications, with a built-in safety feature that effectively reduces the risk of an exposure incident. The standard also requires that engineering controls be examined and maintained or replaced on a regular schedule to ensure their effectiveness.
| Item | Canada | United States |
|---|---|---|
| Device classification | Class II medical device | Class II device, performance standards |
| Market pathway | Device licence under section 32 | Premarket notification where applicable |
| Safety needle obligation | Employer duty to provide a safety-engineered needle where hollow-bore work is required, in provinces with such regulation | Engineering controls required, with sharps with engineered sharps injury protections named |
| Product definition of a safety needle | Defined against the risk of skin puncture injury, with a device licensing condition | Defined by the built-in safety feature that reduces exposure risk |
| Container | Sharps disposal container as an engineering control | Sharps disposal containers named in the engineering controls definition |
| Maintenance | Employer workplace duties under provincial regulation | Engineering controls examined and maintained on a regular schedule |
| Guidance | CCOHS needlestick injury guidance | OSHA bloodborne pathogens standard |
The purchasing consequence is straightforward. A safety-engineered set is not an upgrade item to be swapped in when the budget allows in provinces that require it; it is what the employer must provide. A buyer comparing a plain winged set against a protected one is comparing a product against a legal requirement.
What else belongs on a draw tray?
A draw tray is a system, and the needle is only its sharpest part.
- Skin preparation. Alcohol prep pads, allowed to dry before the puncture.
- The tube or tubes. The order of draw decides which tube is filled first, and the CLSI sequence is the same in both countries.
- A dressing afterwards. A gauze square and tape, or a self-adhesive dressing. Sterile gauze sponges in a case quantity cover both the draw tray and the wider clinic.
- The sharps container. Puncture-resistant, positioned within arm's reach, and replaced before it is full. A container across the room is the finding an inspector writes down.
- Gloves. Changed between patients, and chosen for fit rather than for chemical resistance in this task.
Assembling the tray as a single repeatable order rather than six separate purchases is what stops the "we ran out of the right gauge" conversation on a Friday afternoon.
Sources
- 21 CFR 880.5570, Hypodermic single lumen needle
- 21 CFR 862.1675, Blood specimen collection device
- OSHA, 29 CFR 1910.1030 Bloodborne pathogens
- Ontario, O. Reg. 474/07 Needle safety
- Medical Devices Regulations, SOR/98-282
- CCOHS, Needlestick and sharp injuries
- CLSI, Order of blood draw tubes and additives
- CLSI, standards programme
- CLSI, about the institute
- FDA, Premarket notification 510(k) database
- FDA, Device registration and listing database
- Transportation of Dangerous Goods Regulations, SOR/2001-286
- Public Health Ontario, Specimen acceptance criteria
- Public Health Ontario, Test information index
- WHO, Laboratory Biosafety Manual, 4th edition
- OSHA, 29 CFR 1910.151 Medical services and first aid
- Canadian General Standards Board
Ordering for a clinic, laboratory or care home? Wholesale and multi-site ordering covers account setup and case pricing, and the B2B wholesale collection lists the lines stocked for institutional buyers. Sites that also run an in-house sterilizer can start with the biological indicator 5-pack trial.
Related reading
- Serum separator tubes and the order of draw: what changes at the border
- Cutting sample rejection rates: six failure modes for Canadian labs
- Diagnostic laboratory supply checklist
Frequently Asked Questions
What is a butterfly needle used for?
It is used where a vein is small, fragile or awkward to reach. The wings give the collector a grip close to the puncture site, and the short length of tubing between the needle and the connector absorbs patient movement so it is not transferred straight into the vein.
Which gauge butterfly needle should a clinic stock?
Most clinics cover the range with one mid-range gauge as the default and one finer gauge for fragile veins, rather than three partly used boxes. Gauge runs backwards: a higher number means a smaller bore.
Is a butterfly needle regulated differently in Canada and the US?
The device is a Class II medical device in both countries, but the pathway differs. In the United States it sits in 21 CFR 880.5570 as a Class II device with performance standards, and in Canada it is a Class II device requiring a device licence applied for under section 32 of the Medical Devices Regulations.
Does Canadian law require a safety-engineered needle?
It depends on the province. Ontario's needle safety regulation requires that, when a worker is to do work requiring the use of a hollow-bore needle, the employer shall provide the worker with a safety-engineered needle that is appropriate for the work, and it defines a safety-engineered needle by reference to the risk of skin puncture injury.
How does the US rule approach the same risk?
As an engineering control rather than a product definition. OSHA's bloodborne pathogens standard defines engineering controls to include sharps disposal containers, self-sheathing needles and safer medical devices such as sharps with engineered sharps injury protections and needleless systems, and requires those controls to be examined and maintained or replaced on a regular schedule.
Does a butterfly set change the order of draw?
No. The CLSI order of draw is the same for specimens collected by syringe, by tube holder, or into tubes pre-evacuated at the time of collection, so a winged set does not change which tube is filled first.
What causes a haemolysed specimen from a fine-gauge set?
Force. A fine-bore needle pushing into a vacuum tube fills slowly, and applying pressure to speed it up is a common way to damage cells. Use the gauge that suits the vein, and let the tube fill at its own rate.
CliniEco Medical supplies winged infusion sets, needles, sharps containers, gauze, gloves and the wider clinic consumable lines described in this article. Health Canada MDEL #35334. This article is written for clinic, laboratory and procurement professionals and is not clinical guidance; device selection and collection technique belong to the collecting professional.
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