Capillary nail refill test

Alternative names
Nail blanch test; Capillary refill time; CRT

Definition
This quick test is performed on the nail beds o monitor tissue perfusion (the amount of blood flow to tissue) and dehydration.

How the test is performed

Pressure is applied to the nail bed until it turns white, indicating that the blood has been forced from the tissue (blanched). Once the tissue has blanched, pressure is removed.

The health care provider will measure the time it takes for blood to return to the tissue, indicated by a pink color returning to the nail.

How to prepare for the test
No preparation is necessary for the test.

How the test will feel
There will be minor pressure to the bed of your nail but it should not cause discomfort.

Why the test is performed
Oxygen, which is critical to the survival of tissue, is carried to various parts of the body by the blood (vascular) system. This test measures how well the vascular system is functioning in your extremities. If you are dehydrated, or tissue perfusion is blocked by other means, this quick test can alert you or your health care provider that care needs to be taken to restore normal vascular flow.

Normal Values
If there is good perfusion to the nail bed, a pink color should return in less than 2 seconds after blanching.

What abnormal results mean
Blanch times that are greater than 2 seconds may indicate:

What the risks are
No risks are associated with this test.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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