Capillary sample

Definition

A capillary sample is a blood sample collected by pricking the skin. Capillaries are tiny blood vessels near the surface of the skin.

Alternative Names

Blood sample - capillary; Fingerstick; Heelstick

How the Test is Performed

The test is done in the following way:

How the Test will Feel

Some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the Test is Performed

Blood transports oxygen, food, waste products, and other materials within the body. It also helps regulate body temperature. Blood is made up of cells and a fluid called plasma. Plasma contains various dissolved substances. The cells are mainly red blood cells, white blood cells, and platelets.

Because blood has many functions, tests on the blood or its components provide valuable clues in the diagnosis of medical conditions.

Capillary blood sampling has several advantages over drawing blood from a vein:

Disadvantages to capillary blood sampling include:

What Abnormal Results Mean

Results vary depending on the test done. Your health care provider can tell you more.

Risks

Risks of this test may include any of the following:

References

Garza D, Becan-McBride K. Capillary of dermal blood specimens. In: Garza D, Becan-McBride K, eds. Phlebotomy Handbook. 10th ed. Upper Saddle River, NJ: Pearson; 2018:chap 11.

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. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 31.


Review Date: 5/24/2021
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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