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Capillary Blood Sampling Procedure in Pediatric
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American Journal of
Biomedical Science & Research
Capillary blood collection has been known around for decades.
When it began, the procedure was used to obtain blood from infants
for genetic screening tests. Newborn screening is nowadays the
routine practice of testing every newborn for certain harmful or
potentially fatal disorders that are not otherwise apparent at birth.
Some examples are: phenolketonuria, congenital hypothyroidism,
acidaemia, glutaric aciduria type 1 and homocystinuria (pyridoxine
Early detection allows treatment that may prevent development
of serious health problems. Newborn screening tests help to identify
potentially treatable or manageable congenital disorders within
and serious lifelong disabilities can be avoided or minimized
critically ill neonates also frequently require repeated analysis of
blood chemistry, hematology and blood gas values in addition to
mandated metabolic screening.
In pediatrics it is especially important to obtain small but
adequate amounts of blood. Drawing blood by venipuncture from
too large quantities of blood may result in anaemia. Additionally
infants have a limited number of sites that can be used for arterial or
venous sampling. That is why blood sampling for infants vary from
with a blade safety lancet version. Due to this fact different blood
drawing technique needs to be used and several conditions must
Choice of Site
According WHO guidelines on drawing blood: best practices
in phlebotomy, the heel is usually the preferred site for capillary
testing in pediatric and neonatal patients . It is crucial to choose
an adequate part of the heel. When puncturing an infant’s heel,
the site must be on the plantar surface medial posteriorly from
the heel bone (calcaneus) is not located beneath these areas, so
there is no risk of bone violation. Safest sites for heel stick are outer
edges of heel (Figure1). Area between outer edges may be used as
site selection is important for minimizing pain and avoiding contact
HTL-Strefa S.A., Regulatory Affairs Department, Poland
To Cite This Article: Malinowski M. Capillary Blood Sampling Procedure in Pediatric Population. 2020 - 9(4). AJBSR.MS.ID.001406. DOI:
Received: March 13, 2020; Published: July 08, 2020
Capillary blood sampling is an essential method of blood collection performed by nurses of all skill levels to obtain samples for routine laboratory
tests in neonates. Newborn screening tests require small, but adequate amounts of blood. Accuracy of their results depends, however, on proper
sample collection technique. Heel sticks are the most commonly performed invasive procedures in neonatal intensive care units. Clinical guidelines
recommend drawing blood from an infant’s heel from a very precise site to avoid trauma, pain and tissue damage in infants.
Abbreviations: AWHONN: Association for Women’s Health, Obstetric and Neonatal Nurses; NANN: National Association of Neonatal Nurses;
WHO: World Health Organization
American Journal of Biomedical Science & Research
Am J Biomed Sci & Res Copy@ Malinowski M
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
a) The posterior curvature of the heel;
b) The central area of the infant foot (area of the arch).
and cartilage. The arch area offers no advantage over puncturing
the heel and must not be used;
distance from skin surface to bone in the thickest portion of the
contaminate the blood specimen;
f) Earlobes .
Figure 1: Procedure of capillary blood sampling from the infant’s heel. a) Recommended test sites. Infants have a limited number of sites that can
be used for blood sampling. That is why blood is usually drawn from an infant’s heel; b) Unlock the device by pressing the safety lock; c) Place
the device on the previously cleaned test site and press the trigger to activate the device; d) Collect blood sample and discard the used device in
Apart from choosing an adequate site on the infants heel,
incision depth is equally important, as the heel callus is still
forming and it is crucial not to interfere into bone formation. The
recommended incision length depends on the age of the patients
and its weight (Table 1). Various publications for the newborn
a 3 kg baby from outer skin surface to bone for medial and lateral
heel is 3.32 mm. The posterior heel site should be avoided, to reduce
the risk of calcaneal puncture and subsequent osteochondritis. A
lancet slightly shorter than the estimated depth needed should be
used because the pressure compresses the skin; thus, the puncture
depth will be slightly deeper than the lancet length. In general, heel
at any other site .
Table 1: Recommended depth and applications for use for skin puncture to collect blood from an infant’s foot.
Applications for use Incision depth (mm) Incision width (mm)
Disinfection of the Site
The skin puncture site must be properly cleansed using sterile
cotton or gauze and disinfected with an appropriate disinfected
agent. For adults an alcohol is preferably to clean the site. However,
some discrepancies appear when it come for pediatric population.
Although many antiseptics have been used in neonates for several
decades, there is no clear guidance regarding the best antiseptic
for use in neonatal intensive care unit. Current evidence based on
antiseptic agent over another.
 rather than povidone iodine because blood contaminated
with povidone iodine may falsely increase levels of potassium,
phosphorus or uric acid in laboratory test results. According
to the Association for Women’s Health, Obstetric and Neonatal
Nurses (AWHONN) and the National Association of Neonatal
Am J Biomed Sci & Res
American Journal of Biomedical Science & Research
Copy@ Malinowski M
should be use as disinfected agents and isopropyl alcohol usage
is discouraged because less effective, drying to skin. Both of them
must be completely removed with sterile water or sterile saline to
an evidence based review was published concluded some evidence
including avoiding of alcohol and povidone iodine. In the extreme
preterm neonates topical antiseptics should be used with special
alcohol wipes should not be used for skin preparation in neonates
and premature infants because it can cause burns and blisters.
Tepid plain water is preferable .
Type of Devices
Historically, skin puncture has been performed with either
a sterile disposable surgical blade or lancet. The surgical blade
presents hazards to both the infant and the blood drawer. Since
the depth of puncture cannot be precisely controlled, the infant
devices have different tip lengths and thus make a shallower or a
deeper puncture. Some of these devices puncture the skin, while
others provide an incision, depending upon the design features.
These products are designed to control the length and depth of the
yield single drops for capillary blood in older children and adults.
for capillary heel sampling in infants. The devices use a surgical
steel blade that slices, rather than stabs. The depth and length of
incision are then better controlled by this kind of device . The
a plastic holder and, upon release, sweeps down to make a small
incision and then automatically retracts upward back into the
incision devices based on less damage to the heel, less collection
time, fewer punctures required, less haemolysis in samples, less
pain, and better wound healing. Devices with an arched shaped
incision provide better quality blood samples, require fewer heel
is effective in providing a quality sample, reducing: the number
of heel puncture sites per test, the time taken to complete the
test, the need for squeezing the heel, bruising, the time the baby
cried, and the need to repeat the test . The selection of the
most appropriate heel stick device in this fragile population, who
undergo numerous capillary blood collections procedures, may
related to prolonged distress and repeated pain exposure in the
neonatal period .
Heel stick is a minimally invasive and easily accessible way
of obtaining capillary blood samples for various laboratory
sampling had obvious applications in this area. To get a sample of
capillary blood, some practical skills and knowledge how to avoid
The development of newer, more effective, and less painful lancing
devices may increase the relative utility of heel stick.
of newborn heel skin punctures based on anatomical measurements and
clinical practice guideline. Association of Women’s Health, Obstetric
and Neonatal Nurses and the National Association of Neonatal Nurses. J
11. Vertanen H, Fellman V, Brommels M, Viinikka L. (2001) An automatic
incision device for obtaining blood samples from the heels of preterm
infants causes less damage than a conventional manual lancet. Arch Dis
12. Hammermeister M, Baskin L, Lemaire C, Naugler C. (2013) Comparison
of two infant lancet devices on ease of use and post lance bleeding times.