Capillary blood sampling
Finger and heel prick sampling, and how capillary samples differ from venous ones.
When it is used
Capillary sampling collects small volumes from a skin puncture. It is used for some point-of-care tests, for infants, and where only a small volume is needed.
Sites
In adults and older children, the side of a fingertip. In infants, the heel, using only the sites that avoid the heel bone. Heel pricks should only be done by people trained for it.
Technique
Clean and dry the site, use a lancet suited to the patient, wipe away the first drop, and collect the following drops without squeezing hard, which dilutes and haemolyses the sample.
Capillary is not venous
Capillary blood is a mix of arterial and venous blood with tissue fluid, so some results differ from venous samples. Label the sample as capillary.
General information only. It is not accredited CPD and does not replace your training, your employer's procedures or the receiving laboratory's requirements.
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