A blood lancet, or simply lancet, is a small medical implement used for capillary blood sampling. A blood lancet is similar to a small scalpel but with a double-edged blade or needle. Lancets are used to make punctures, such as a fingerstick, to obtain small blood specimens. Blood lancets are generally disposable.
Lancets are also used to prick the skin in skin testing for allergies.
A blood-sampling device, also known as a lancing device, is an instrument equipped with a lancet. It is also most commonly used by diabetics during blood glucose monitoring. The depth of skin penetration can be adjusted for various skin thicknesses. Long lancing devices are used for fetal scalp blood testing to get a measure of the acid base status of the fetus.
Blood lancet Wikipedia
The small capillary blood samples obtained can be tested for blood glucose, hemoglobin, and many other blood components.