Common Mistakes with Butterfly Needle Use
, by Andrew Odgers, 15 min reading time
Technique
Common Mistakes with Butterfly Needle Use and How to Avoid Them
Even experienced phlebotomists make avoidable errors with butterfly needles. The most common mistakes lead to haemolysed samples, failed collections, patient discomfort, and needlestick injuries that could all be prevented with correct technique. This guide identifies each mistake, explains why it happens, and gives the practical correction.
Before insertion
Setup and preparation mistakes
Choosing the wrong gauge for the vein
Selecting a gauge that is too wide for the target vein is one of the most common errors in butterfly needle use. Forcing a 21 gauge needle into a small hand vein or a fragile vein in an elderly patient causes immediate trauma, pain, and an elevated risk of haematoma. The vein collapses around the needle and either fails to yield a sample or produces a haemolysed result.
The correction is to assess the vein visually and by palpation before selecting the gauge. A vein that is visible but narrow, soft, or fragile to the touch calls for a 23 gauge needle rather than the default 21. Very small veins or those in neonatal or paediatric patients require a 25 gauge. Starting with the correct gauge significantly reduces the need for second attempts.
Not priming the tubing before collection
Some practitioners skip the discard tube step, either because they are not aware of it or because they want to avoid using an extra tube. The result is that the air in the butterfly tubing enters the first collection tube along with the blood. This air-blood mixture causes haemolysis in the sample, which is then rejected by the laboratory. The practitioner must re-bleed the patient to obtain a usable sample, costing more time and causing more patient discomfort than the discard tube would have.
The correction is to treat the discard tube step as non-negotiable in every butterfly needle collection. A small 2ml discard tube is sufficient to clear the dead space in most butterfly needle tubing lengths. The discard tube protects the integrity of every diagnostic tube that follows it.
Using a butterfly needle for long-duration infusions
A butterfly needle is a steel-tipped device, not a flexible plastic cannula. Using one for an infusion that is expected to last several hours, or for a situation where the patient will move substantially, risks vein perforation and tissue infiltration. Steel needles do not soften in the vein the way a plastic IV cannula does, and any significant movement causes the rigid tip to cut into the vein wall.
The correction is to use a butterfly needle only for short-duration infusions in controlled settings, or to insert a standard IV cannula when access will be needed for longer than one to two hours or when the patient cannot maintain a stable position.
During insertion
Insertion technique mistakes
Inserting at too steep an angle
Approaching the vein at too steep an angle is the most common insertion error and causes the needle tip to pass through the back wall of the vein. The flash of blood in the tubing may still appear briefly before disappearing, leading the practitioner to believe they are in the vein when they are actually through it and collecting into surrounding tissue.
Butterfly needles should be inserted at 15 to 20 degrees for most superficial veins. For very superficial veins such as dorsal hand veins the angle should be even lower. Maintaining a shallow angle and advancing the needle slowly until the flash is confirmed is the correct technique. If the flash appears and then stops, the needle has gone through the back wall and should be withdrawn slightly while maintaining the syringe vacuum to check if flow resumes.
Not advancing the needle far enough after the flash
Seeing the flash and stopping immediately means the needle tip is just inside the vein but the bevel may not be fully within the lumen. Any slight movement can then pull the tip back out. Blood will begin to slow or stop and the collection will fail.
After confirming the flash, lower the insertion angle further and advance the needle a few additional millimetres along the axis of the vein before taping the wings flat. This ensures the needle tip is securely within the vein lumen and reduces the risk of displacement during collection.
Probing inside the tissue
When a first attempt fails, some practitioners try to redirect the needle inside the tissue by moving it laterally or at a steep angle while it is still under the skin. This damages tissue, collapses the target vein, and causes unnecessary pain. It also dramatically increases the risk of haematoma.
The correct response to a failed attempt is to withdraw the needle completely, apply brief pressure to the site, and select a new site for a second attempt. A clean second puncture on a different vein is far less traumatic than probing with a needle already in the tissue.
During collection
Sample collection mistakes
Errors during the collection phase are among the most common causes of haemolysed or contaminated samples.
- Using the wrong tube vacuum for the gauge. Collecting into a standard adult vacutainer tube with a 25 gauge butterfly needle creates a vacuum mismatch. The high vacuum draws blood faster than the narrow gauge allows, creating turbulence and shear that haemolyses red cells. The solution is to use paediatric tubes with narrow gauge needles, or to allow the tube to fill more slowly without forcing.
- Collecting tubes in the wrong order. The standard tube order of draw exists to prevent additive carry-over between tubes. Collecting a coagulation tube before a plain serum tube, or a citrate tube before a lavender EDTA tube, risks cross-contamination that invalidates the results. The tube order applies equally to butterfly needle collections as to straight needle collections.
- Not mixing additive tubes immediately. Tubes containing anticoagulants, clot activators, or other additives require immediate gentle inversion after collection to ensure the additive mixes evenly with the blood. Leaving tubes unmixed on the tray while continuing the collection sequence leads to clotted samples or uneven additive distribution.
- Withdrawing the needle before removing the last tube. Removing the needle while a vacutainer tube is still attached to the holder creates a brief vacuum that draws blood back from the tubing into the needle and can cause a splash or spray at the point of disconnection. Always remove the last tube from the holder before withdrawing the needle from the vein.
- Allowing the needle to move during collection. Even with the flexible tubing providing some protection, significant patient movement can still displace the needle from the vein or cause the tip to press against the vein wall, slowing or stopping flow. Instructing the patient to remain still and supporting the hand or arm with a free hand during collection avoids this problem.
After collection
Post-collection and sharps safety mistakes
Not activating the safety mechanism immediately
The single most dangerous mistake with butterfly needles is withdrawing the needle from the vein and placing it on the tray while attending to the patient before activating the safety sheath. The unsheathed needle on an open surface is the most common mechanism of needlestick injury in phlebotomy settings.
The safety mechanism should be activated in the same motion as withdrawing the needle, before the device touches any surface. For retractable designs this happens automatically. For sheath designs the clinician must consciously activate the sheath as the needle exits the skin. This step should be practised until it is automatic.
Recapping the needle manually
Attempting to recap a used butterfly needle by placing the cap on a surface and guiding the needle into it single-handedly is a high-risk technique that causes needlestick injuries. It should never be used. Butterfly needles with safety mechanisms do not require recapping. Those without safety mechanisms should not be in clinical use in the UK, where sharps safety legislation requires safety-engineered devices.
Disposing of the entire device without activating safety first
Placing the entire butterfly needle assembly, including the luer fitting end, into a sharps bin without first activating the needle safety mechanism leaves a live sharp protruding from the bin contents. This creates injury risk for anyone handling the bin and for waste management staff. Always activate the safety mechanism before disposal, regardless of how quickly you intend to dispose of the device.
The right equipment helps
Butterfly needles designed for safe, controlled collections
Charles Medical butterfly needles include integrated safety mechanisms across all gauges, reducing the risk of needlestick injury during and after every collection.
For guidance on selecting the right gauge before you begin, see How to Choose the Correct Gauge Butterfly Needle.
Part of the hub
Back to the Butterfly Needle Knowledge Hub
This article is part of our complete butterfly needle knowledge base, covering clinical use, gauge selection, technique, haemolysis reduction, cost analysis, patient guidance, and the full regulatory picture for UK procurement.
Keep reading
Related guides in this hub
What Are Butterfly Needles and How Do They Work covers the full device anatomy for those who want to understand the mechanics behind good technique. Clinical Evidence: Studies Showing Reduced Haemolysis with Butterfly Needles explains why correct technique matters for sample quality. And How Butterfly Needles Help in Reducing Complications in Blood Sample Collection covers the full spectrum of complications that good technique prevents.
Frequently asked
Butterfly needle technique questions answered
Why does my butterfly needle collection keep producing haemolysed samples?
The most common causes are skipping the discard tube, using a gauge that is too narrow for the collection tube vacuum, collecting too quickly, or using a collection tube that is too large relative to the needle gauge. Check that you are using a discard tube, match your gauge to the appropriate tube size, and allow collection to proceed at a natural rate without forcing. If the problem persists in a specific patient group, consider moving to a narrower gauge with smaller paediatric collection tubes.
What should I do if the blood stops flowing mid-collection?
First check whether the needle has shifted position. Gently lower the insertion angle slightly and apply gentle outward tension on the wings. If flow does not resume, the needle tip may be against the vein wall. A slight withdrawal of one to two millimetres often resolves this. If flow still does not resume, withdraw the needle completely, apply pressure, and assess a new site. Do not probe inside the tissue.
How do I avoid needlestick injuries with butterfly needles?
Always use butterfly needles with integrated safety mechanisms and activate the mechanism as a single continuous motion with needle withdrawal. Never set down an unsheathed needle. Never attempt to recap a used needle. Dispose of the activated safety device directly into the sharps bin without placing it on any surface first. These three habits together account for the vast majority of needlestick injury prevention in butterfly needle use.
Is it ever acceptable to use a butterfly needle without a discard tube?
No. The discard tube is required to clear air from the butterfly needle tubing before diagnostic samples are collected. Skipping it risks haemolysis in the first diagnostic tube and potentially compromises the entire collection. The discard tube step is non-negotiable in butterfly needle blood collection protocol.
What angle should a butterfly needle be inserted at?
Approximately 15 to 20 degrees for most superficial veins. For very superficial veins such as dorsal hand veins, a shallower angle of 10 to 15 degrees is more appropriate. After the flash of blood is confirmed, lower the angle further before advancing the needle to ensure the bevel is fully within the vein lumen.