Lifespan's A - Z Health Information Library

The capillary nail refill test is a quick test performed on the nail beds to monitor tissue perfusion (the amount of blood flow to tissue) and dehydration.

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

No preparation is necessary for the test.

There will be minor pressure to the bed of your nail, which should not cause discomfort.

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 (hands and feet), which are the parts of your body farthest from the heart. 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.

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

Blanch times that are greater than 2 seconds may indicate:

• Dehydration
• Shock
• Peripheral vascular disease (PVD)
• Hypothermia

No risks are associated with this test.