Heel stick is a minimally invasive and easily accessible way of obtaining capillary blood samples for various laboratory tests, especially newborn screens and glucose levels. However, thanks to improved laboratory techniques that require smaller sample volumes and improved automated heel lancing devices that minimize trauma and pain,  heel stick is a viable method of obtaining blood for many routine blood tests.  Heel stick sampling can also help preserve venous access for future intravenous (IV) lines.
Some evidence exists that in term neonates, skilled venipuncture may result in fewer total punctures and less pain than heel stick. A Cochrane review first published in 1999 and updated in 2011 suggests that it may in fact be the procedure of choice in this population.  However, these results may not be extrapolatable to preterm infants or infants who require multiple or frequent blood sampling.  In addition, the development of newer, more effective, and less painful lancing devices may increase the relative utility of heel stick.
Heel stick blood sampling is indicated whenever capillary blood is an acceptable source. Such situations include the following:
The sample required is relatively small
Heel stick samples can be used for general chemistries and liver function tests, complete blood counts (CBCs), toxicology, newborn screening, bedside glucose monitoring, and blood gas analysis. [5, 6, 7, 8]
Heel stick should not be performed if any significant injury, infection, anomaly, or edema is present on the sampling area of the heel. 
At present, coagulation studies may not be performed with capillary samples. Blood tests that require relatively larger sample volumes may not be feasible with heel stick samples. Blood cultures require perfectly sterile technique and, therefore, may not be done with samples obtained via heel stick. Certain other sophisticated tests may also not be performed on heel stick samples (eg, chromosomal analyses and certain immunoglobulins and titers).
When ordering a laboratory test that is sent to another facility or is out of the ordinary, check with the laboratory to determine which type of blood sample is required.
The materials required for a heel stick include the following:
A heel-warming device (if desired)
Antiseptic solution (eg, povidone-iodine, chlorhexidine, or alcohol, depending on the local facility's policy)
[BD, Franklin Lakes, NJ]), sized appropriately for the infant's weight - A 0.65 mm incision depth is appropriate for infants weighing 1 kg or less; a 0.85 mm incision depth is appropriate for small-for-gestational-age (SGA) infants and premature infants who weigh more than 1 kg; and a 1 mm incision depth is appropriate for term infants aged 6 months or younger
A towel or pad to cover bed linens
An appropriate blood collecting apparatus, including a hematology tube, a capillary blood gas tube, filter paper, a serum separator tube, and a capillary tube
A bandage or gauze to dress the wound after the procedure
Standard local or systemic pharmacologic anesthesia is not required for heel stick sampling. Local anesthetics may interfere with the quality of the blood sample.
Anesthesia for heel stick in infants can involve oral sucrose, ambient light and noise reduction, and swaddling. Sucrose has been shown to have a substantial anesthetic effect in multiple trials, though an optimal dose has not been definitively established.  It may be administered with a dropper, a needleless syringe, or a pacifier dipped in a dose of approximately 0.1-1 mL.
Swaddling, bringing the infant's hands to the midline, and minimizing environmental stimulation has also been shown to have an effect on how infants tolerate this painful procedure. 
Developmentally appropriate positioning, should be implemented when possible. The heel stick sample is obtained most easily with the infant supine (see the image below).
Proper site selection (see the image below) is important for minimizing pain and avoiding contact with the calcaneus. The posterior pole of the heel should not be used for a heel stick, because this site is where the calcaneus is in its most superficial position. 
Heel Stick Sampling
If heel warming is desired, apply a heel warmer according to the manufacturer’s directions for approximately 5 minutes before performing the heel stick. (Some studies have found heel warming to offer no improvement in blood volume collected.  )
Put on gloves. Prepare the automated heel-lancing device according to the manufacturer’s directions. Prepare an adequate area around the heel stick site with antiseptic solution.
Position the heel between thumb and forefinger, with the fingers underneath the calf and posterior ankle and the thumb over the ball of foot or arch (see the image below). Apply a small amount of pressure to place the foot in a comfortable dorsiflexed position.
Place the automated lancing device on the appropriate area on the side of the heel (see the image below), then activate it.
Apply mild pressure with thumb and fingers. Avoid excessive squeezing or milking of the heel; this may lead to greater hemolysis and more pain.
Wipe away the first drop of blood, and collect the sample. Fill the capillary tube by touching the open tip of the tube to a blood drop, which is drawn into the tube by capillary action. Collect blood drops into hematology or chemistry tubes (see the image below), taking care to avoid excessive scooping of blood from the adjacent skin with the lip of the collection tube, which can interfere with test results.
Blot blood drops onto appropriate areas on the filter paper according to the laboratory's instructions; methods of collecting filter paper samples for newborn screens have strict guidelines and vary between laboratories. If blood stops flowing, try to wipe away any clot that may have formed at the incision site with gauze or an alcohol wipe. Release pressure to allow capillary refill, then reapply pressure to allow a blood drop to form again.
When sampling is complete, apply pressure to the incision site until bleeding stops. Apply gauze or a bandage.
Complications of Procedure
Complications of heel stick include the following:
A too-deep incision (potentially making contact with calcaneus)
Inaccurate results (eg, hemolysis causing hyperkalemia, air bubbles causing erroneous blood gas results, platelet clumping)