A butterfly needle, formally known as a winged infusion set, is a specialized device for accessing veins for blood collection or short-term intravenous (IV) therapy. It features a thin, small-gauge needle attached to flexible tubing that connects to a collection hub or an IV line. The defining characteristic is the pair of flexible plastic “wings” that provide a secure grip and greater control during insertion. This design is particularly useful for accessing small, fragile, or rolling veins, often encountered in pediatric, geriatric, or oncology patients, where a standard straight needle might be difficult to manage.
Preparing the Supplies and Insertion Site
Before beginning the procedure, all necessary supplies must be gathered and organized to ensure a smooth and sterile venipuncture. Supplies include the butterfly needle set, a collection device (tube holder or IV adapter), a tourniquet, antiseptic wipes, sterile gauze, adhesive dressing, and a sharps container. Selection of the correct needle size is important; butterfly needles commonly range from 21-gauge to 25-gauge. Higher gauge numbers indicate a thinner needle, which reduces patient discomfort but may slow blood flow.
Attention then turns to selecting the optimal insertion site, generally a visible and palpable vein in the antecubital fossa or forearm. The tourniquet is applied three to four inches above the chosen site to temporarily impede venous return, causing the vein to engorge. The tourniquet must remain in place for no more than one minute to prevent hemoconcentration, which can affect laboratory results.
The site must be thoroughly cleansed with an antiseptic solution, such as 70% isopropyl alcohol or chlorhexidine. The cleansing motion should move outward in a circular or spiral pattern from the puncture point to avoid dragging contaminants back over the clean area. The antiseptic must be allowed to air-dry completely before venipuncture to maximize the germicidal effect and prevent a stinging sensation upon needle entry.
The Step-by-Step Insertion Technique
To begin the insertion, the clinician must firmly grasp the textured wings of the butterfly needle between the thumb and index finger, ensuring the needle’s bevel is facing upward. This grip allows for precise maneuvering and control during the shallow entry required. The non-dominant hand anchors the vein by gently pulling the skin taut below the puncture site, which prevents the vein from rolling.
The needle is introduced through the skin and into the vein at a shallow angle, typically between 10 and 15 degrees. This flat trajectory is suited for superficial veins and is less likely to pierce the posterior wall of the vessel. Successful entry is confirmed by observing a “flashback,” which is a small amount of blood entering the clear tubing immediately following the puncture.
Upon seeing the flashback, the needle should be advanced slightly further to ensure the entire beveled opening rests securely within the vein lumen. The wings are then secured to the skin with medical tape to prevent movement or dislodgment during collection or infusion. Maintaining this stable position avoids tissue trauma or the loss of venous access.
Managing Blood Collection or IV Administration
Once the butterfly needle is secured, the collection or infusion process begins by attaching the appropriate hub or adapter to the tubing’s connector. For blood collection, vacuum tubes are pushed onto the adapter, allowing the vacuum to draw blood into the tube. When collecting multiple tubes, a specific “Order of Draw” must be followed to prevent cross-contamination of additives, which could skew laboratory results.
For coagulation studies requiring a light-blue top tube, a non-additive “discard tube” must be drawn first. This removes the air occupying the tubing’s dead space, ensuring the correct blood-to-anticoagulant ratio is maintained for accurate testing. The tourniquet must be released once blood flow is established or within a maximum of one minute after application.
If the butterfly is used for IV administration, the primed IV line is connected to the adapter, and the flow rate is established. The insertion site should be monitored for signs of infiltration, such as swelling or blanching, indicating fluid is leaking into the surrounding tissue. The tubing’s flexibility allows the patient greater freedom of movement while maintaining secure, short-term venous access.
Safe Removal and Sharps Disposal
Once collection or infusion is complete, the focus shifts to safety and site closure. Before withdrawal, the collection device or IV line must be disconnected from the butterfly tubing. A piece of sterile gauze should be placed gently over the puncture site, ready to apply pressure immediately upon needle removal.
The butterfly needle must be removed in one quick, smooth motion, pulling it straight out at the same angle it was inserted to minimize trauma to the vein wall. Firm pressure is immediately applied to the site with the gauze to promote hemostasis and prevent the formation of a hematoma. The patient should maintain pressure on the site for several minutes until bleeding has completely stopped before a final dressing is applied.
Immediately after removal, the safety-critical step is activating the needle’s built-in safety mechanism, which permanently sheaths or retracts the exposed sharp. A used needle should never be manually recapped, as this is the leading cause of accidental needlestick injuries. The entire used butterfly needle set must be disposed of immediately into a rigid, puncture-resistant sharps container.