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In medicine, some blood tests are conducted on capillary blood obtained by fingerstick (or fingerprick) (or, for neonates, by an analogous heelprick). The site, free of surface arterial flow, where the blood is to be collected is sterilized with a topical germicide, and the skin pierced with a sterile lancet. After a droplet has formed, capillary blood is captured in a capillary tube (usually relying on surface tension) or on a membrane.

Advantages

Capillary blood is easy to obtain especially for people with bad veins and infants. This method requires lower blood volumes which reduces the chance of anemia, it can be done from home and requires no training. It is less invasive and cheaper than traditional venous blood sampling. This method could improves lives of patients who need regular check ups, have flaring diseases, or live remotely and have less access to doctors or phlebotomists.

Disadvantages

Capillary blood is more prone to inconsistencies due to the lower blood volume, or differences in drawing capillary blood. Blood cells drawn from fingersticks have a tendency to undergo hemolysis, especially if the finger is "milked" to obtain more blood. When the finger is "milked", the blood dilutes and the quantities of metabolites or biomarkers will be incorrect.

  • Dried blood spot and dried plasma spot - A method where dried capillary blood is used to detect metabolites or biomarkers in blood or plasma.

Fingersticks are routine for adults, but are generally performed on children and the elderly only if a small amount of blood suffices for needed tests. Neonates are given heelpricks instead, as this is less likely to cause permanent damage.

References

  • Heelpricks, section "Blood collection on babies"