A butterfly needle is a device used to draw blood from a vein or inject intravenous (IV) therapy into a vein. A butterfly needle, also called a winged infusion set or scalp vein set, consists of a very thin hypodermic needle, two flexible "wings," a flexible clear tube, and a connector. The connector can be attached to a vacuum tube or blood collection bag, or to an infusion pump tube or IV bag to deliver fluids or medications. Medications can also be administered directly to the connector using a syringe.
Butterfly needles have certain advantages over straight needles. For example, they allow more precise placement, especially in difficult-to-access veins. However, they are not always the best option.
What are butterfly needles used for?
Phlebotomists regularly use butterfly needles to obtain blood samples for complete blood counts (CBC), cholesterol tests , diabetes monitoring , STD screening tests, and other blood tests. These needles are also commonly used in blood banks for people who want to donate blood.
Butterfly needles can also be used to give fluids intravenously if you are dehydrated and cannot drink fluids or cannot drink enough to make up for fluid loss. They are also useful for injecting medications (such as pain relievers ) directly into a vein or for gradual intravenous administration of medications (such as chemotherapy or antibiotics ).
Although butterfly needles can be left in the vein for five to seven days if properly secured, they are most commonly used for short-term infusions.
Although all butterfly needles have the same design, there are variations. Butterfly needles are measured in gauges and generally range in size from 18 to 27. The higher the gauge, the smaller the needle.
By way of illustration, a 27 gauge needle is the size commonly used for insulin injections . Smaller needles are used if the fluid to be injected is thick or if blood is collected for transfusion. Most butterfly needles are no more than three-quarters of an inch (19 millimeters) long.
The IV set or collection container is connected to a tube that is connected to a needle, not a needle. This is helpful as there is less chance of injury from a jerk or fall .
Tubes can range in size from 8 to 15 inches (20 to 35 centimeters). Shorter tubes are used to collect blood. The longest ones are for intravenous infusions and may have roller valves to regulate the flow. The tubes can also be stained so that nurses can distinguish from which line to which line if more than one is used.
Some butterfly plug connectors have built-in "plug" ports that can be inserted into the vacuum tubes. Other connectors have female ports into which syringes or hoses can be inserted.
How are butterfly needles used?
During venipuncture (inserting a needle into a vein), the phlebotomist or nurse will hold the butterfly needle by the wings between the thumb and forefinger. Because the hypodermic needle is short and the grip is close to the needle, a butterfly needle can be positioned more precisely than a straight needle, which can often roll or wiggle in the fingers .
A short, thin needle is inserted into the vein at a slight angle. Once inserted, venous pressure will force a small amount of blood into the clear tube, confirming that the needle is inserted correctly. The wings can also serve to stabilize the needle while it is in place, preventing it from rolling or moving.
After use (blood draw or medication administration), the entire device is thrown into a sharps disposal container. The puncture wound is then bandaged.
Due to their small size (much smaller than an IV catheter ) and shallow angle design, butterfly needles can penetrate superficial veins close to the surface of the skin. This not only makes them less painful to wear, but also allows them to enter the veins. small or narrow, such as in infants or the elderly.
Butterfly needles are ideal for people with small or spastic (wavy) veins and can even be inserted into small veins in the arm, foot, heel, or scalp.
Butterfly needles are great for people who are hesitant to use needles because they are less dangerous.
They are also less likely to cause heavy bleeding, nerve damage, or collapse of the veins after the needle is removed .
Newer models have a locking and sliding sleeve that automatically slides over the needle as it is withdrawn from the vein, preventing needle stick injuries and reusing the used needle.
If you have been told that you have small veins and have had trouble drawing blood in the past, you can request the use of a butterfly needle.
That being said, butterfly needles are not for everyone.
Due to the small size of the needle , blood collection is usually slower . This can be problematic in a blood bank if a person is squeamish or in an emergency when blood is needed quickly. In situations like this, the choice of needle size is key.
Even with routine blood samples, the wrong needle size can lead to a blockage and the need to re-draw if a large amount of blood is required.
Because the needle remains in the hand for the infusion, and not the catheter or PICC line , the butterfly needle can damage the vein if the device is suddenly pulled . Even if a needle of the correct size is used, the needle may become blocked during treatment if it is positioned incorrectly.
In general, butterfly needles should only be used for intravenous infusions of five hours or less.