Lima Memorial Health System Logo
Approximate ER WAIT TIME WAIT TIME MACRO

Health Library

Capillary sample
     
Print-Friendly
Bookmarks

Capillary sample

Blood sample - capillary; Fingerstick; Heelstick

 

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

 

The test is done in the following way:

  • The area is cleansed with antiseptic.
  • The skin of the finger, heel, or another area is 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

 

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:

  • It is easy to obtain (it can be difficult to obtain blood from the veins, especially in infants).
  • There are several collection sites on the body, and these sites can be rotated.
  • Testing can be done at home and with little training. For example, persons with diabetes must check their blood sugar several times a day using capillary blood sampling.

Disadvantages to capillary blood sampling include:

  • Only a limited amount of blood can be drawn using this method.
  • The procedure has some risks (see below).
  • Capillary blood sampling may result in inaccurate results, such as falsely elevated sugar, electrolyte, and blood count values.

 

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:

  • Excessive bleeding
  • Fainting or feeling lightheaded
  • Infection (a slight risk any time the skin is broken)
  • Scarring (occurs when there have been multiple punctures in the same area)
  • Calcified nodules (sometimes occurs in infants, but usually disappear by 30 months of age)
  • Damage to blood cells from this method of collection can sometimes cause inaccurate test results and the need to repeat the test with blood drawn from a vein

 

 

References

Rolon MEDV. Procedures. In: Anderson CC, Kapoor S, Mark TE, eds. The Harriet Lane Handbook. 23rd ed. Philadelphia, PA: Elsevier; 2024:chap 4.

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.

BACK TO TOPText only

  • Phenylketonuria test

    Phenylketonuria test

    illustration

  • Newborn screening testing

    Newborn screening testing

    illustration

  • Capillary sample

    Capillary sample

    illustration

Tests for Capillary sample

 
 

Review Date: 4/25/2023

URAC Seal
Health Content Provider
06/01/2025
A.D.A.M., Inc. is accredited by URAC, for Health Content Provider (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics. This site complied with the HONcode standard for trustworthy health information from 1995 to 2022, after which HON (Health On the Net, a not-for-profit organization that promoted transparent and reliable health information online) was discontinued.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- 2025 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
© 1997- 2025adam.comAll rights reserved.