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D-Dimer Test

A d-dimer test is a blood test that measures a substance that is released when a blood clot breaks up. Doctors order the d-dimer test, along with other lab tests and imaging scans, to help check for blood-clotting problems. A d-dimer test can also be used to check how well a treatment is working.

Why It Is Done

Doctors use the d-dimer test when a person might have a dangerous blood-clotting problem. These problems include:

How To Prepare

No special preparation is required before having this test.

How It Is Done

The health professional drawing your blood will:

  • Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
  • Clean the needle site with alcohol.
  • Put the needle into the vein. More than one needle stick may be needed.
  • Attach a tube to the needle to fill it with blood.
  • Remove the band from your arm when enough blood is collected.
  • Put a gauze pad or cotton ball over the needle site as the needle is removed.
  • Put pressure on the site and then put on a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of a problem from having a blood sample taken from a vein.

WebMD Medical Reference from Healthwise

Last Updated: March 12, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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