Capillary nail refill test

Alternative names:

capillary refill time; CRT; nail blanch test

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, and the time it takes for blood to return to the tissue is measured. This is indicated by a pink color returning to the tissue.

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.