As you might expect, although blood collection procedures learned in phlebotomy training for newborns and infants are not the same procedures as performed in adults. Blood collection performed on newborns and infants uses a technique termed capillary blood collection. Capillaries are tiny blood vessels. Capillary blood collection involves puncturing the skin in order to gain access to the capillary beds, networks of capillaries that lay close to the surface of the skin.
In capillary blood collection, there are two types of devices, called lancets, used instead of needles to access the blood: puncture and incision devices. Puncture devices puncture the skin by vertically inserting a needle or blade into the skin and capillary beds. This type of device is preferable in cases of repeated punctures, such as blood glucose monitoring. The second type, incision devices, slices through the capillary beds. Incision devices are considered to be less painful, offer shorter collection times, and fewer repeat incisions than puncture devices. Both types of lances are available in a range of sizes, depths, and styles. Capillary blood is collected in special capillary tubes.
The site of blood collection should be warm, pink and free of blemishes such as bruises, calluses, scars, and burns. The site should not be swollen or infected. Care should be taken to avoid sites that show signs of previous puncture. To increase blood flow to the collection site, phlebotomists often use a warming device or simply massage the area for a few minutes prior to puncture. Capillary blood collection in newborns and infants is performed in one of two sites, the finger and the heel.
Collecting blood from the fingers, often called a ‘fingerstick’, is recommended in infants over the age of one year. Fingerstick collection is performed using a puncture-type lancet. The puncture is created slightly off-center of the fleshy fingertip, ideally of the non-dominant hand.
The sides and tip of the finger should be avoided since the tissue is about half as thick as the fleshy center. Ideal are the third (middle) and fourth (ring) fingers; the index finger is often callused and contains additional nerve endings. The thumb may be callused and contains a pulse, indicating the presence of an artery. The distance between the bone and surface of the skin in the fifth finger makes it unsuitable for puncture.
Blood collection from the heel is performed in newborns and infants younger than one year of age. The recommended site for heel punctures is inside or outside plantar (bottom) surface of the heel. In premature and small infants, bones in the foot can be less than 2.0mm from the surface of the skin.
Using puncture devices close to the bone risks causing bone, nerve, or cartilage damage; therefore punctures must not be performed on the posterior (back) curve of the heel or arch of the foot. Incision-type devices are recommended for heelstick procedures.
In some cases, such as fragile veins, frequent blood tests and tests requiring only a few drops of blood, capillary blood collection may be performed in adults. Capillary blood collection is not suitable for dehydrated patients or patients with poor circulation.