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Alternative Names Return to topBlood sample - capillary; Fingerstick; Heelstick
Definition Return to top
A capillary sample is a blood sample collected by pricking the skin. Capillaries are tiny blood vessels near the surface of the skin.
How the Test is Performed Return to top
Some blood tests are performed on blood obtained by pricking the skin of the finger, heel, or other areas and collecting a drop (or a few drops) of blood on a test strip or into a small container.
The area is cleansed with antiseptic and pricked with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How the Test Will Feel Return to top
Some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the Test is Performed Return to top
Blood transports oxygen, food, waste products, and other materials within the body. It also helps regulate body temperature. Blood is made up of a fluid called plasma and cells. Plasma contains various dissolved substances. The cellular portion consists primarily of red blood cells, but also includes white blood cells and platelets.
Because blood has multiple functions, tests on the blood or its components can provide valuable clues in the diagnosis of a multitude of medical conditions.
Capillary blood sampling offers several advantages:
There are some disadvantages to capillary blood sampling.
Normal Results Return to top
See the specific test.
What Abnormal Results Mean Return to top
Results vary depending on the test performed.
Risks Return to top
Considerations Return to top
Capillary blood sampling is very useful when very small amounts of blood are needed or when blood is very difficult to obtain, such as in infants. Many times, however, when a larger sample is needed, the blood must be obtained from a vein.
References Return to top
Khan MI, Weinstock RS. Carbohydrates. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 16.
Vajpayee N, Graham SS, Bem S. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, Pa: Saunders Elsevier; 2006:chap 29.Update Date: 5/2/2009 Updated by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.