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

Colored nailpolish should be removed before this test.

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

Tissues need oxygen to survive. Oxygen is carried to various parts of the body by the blood (vascular) system.

This test measures how well the vascular system works in your hands and feet -- the parts of your body that are farthest from the heart.

If there is good blood flow to the nail bed, a pink color should return in less than 2 seconds after pressure is removed.

Blanch times that are greater than 2 seconds may indicate:

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

No risks are associated with this test.