The neonatal heel prick, also known as a dermal puncture, is by far the most popular way to collect blood from newborns and infants up to about six months of age. Dermal punctures are preferable because, when done correctly, they are guaranteed to produce blood, removing the uncertainty of needle sticks. The heel prick is used to fill small collection tubes called pediatric “bullet” tubes, named after their shape. The steps for a proper neonatal heel prick are as follows:
1 – Be sure to place the infant in a safe, comfortable position, face-up, either on an infant draw table or a parent’s lap. Leave the baby as swaddled as possible for comfort, only exposing one leg for the draw.
2 – Using an approved heel-warmer pad, heat the baby’s entire foot for approximately one minute until the skin is very warm to the touch. This technique dilates capillaries in the area, maximizing blood flow.
3 – Gently flexing the foot upward, encase the baby’s entire foot in one hand. Rather than pinching the heel directly, you will be using a full-foot massage technique to collect the blood. This ensures both the baby’s comfort and a much better blood flow.
4 – Wipe the heel with an alcohol pad and allow it to air dry. Do not blow on the foot as it dries. Softly squeeze the baby’s foot so that the skin of the heel is bunched up. Press the lancet flat against the inner, bottom edge of the heel, along the same side as the big toe, and depress the trigger. The lancet will make a quick swipe of the heel with a clicking sound.
5 – Wipe the first drop of blood away with a clean cotton pad. Then, using a massaging pattern, gently squeeze and release the foot several times, allowing blood drops to form a drip from the end of the heel.
6 – As the blood drops collect, let them flow openly into the bullet tube or PKU card without scraping the blood along the skin. This helps avoid damaging, or “hemolysing”, the red blood cells.
7 – When a sufficient amount of blood has been collected, place a clean cotton pad across the puncture site and apply moderate pressure for approximately one minute.
With your free hand, close the cap of the tube and gently invert it several times to mix the tube additive with the blood. Don’t shake too vigorously.
Heel sticks are not appropriate for every type of lab test. In the event that specialty testing is ordered for blood banking, blood culture, or tests that require larger amounts of product, you will need to perform a regular venipuncture with a needle. For babies, use a tourniquet that has been cut smaller, and spend extra time locating the antecubital vein on one or both arms. Use a 23g or 25g sized butterfly needle, and be sure that the arm is completely restrained for the duration of the draw to avoid an injury.