Pressure is applied to the nail bed until it turns white. This indicates that the blood has been forced from the tissue under the nail. It is called blanching. Once the tissue has blanched, pressure is removed.

While the person holds their hand above their heart, the health care provider measures the time it takes for blood to return to the tissue. Return of blood is indicated by the nail turning back to a pink color.

Remove colored nail polish before this test.

There will be minor pressure to the bed of your nail. This 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
• Hypothermia
• Low blood pressure
• Peripheral vascular disease (PVD)
• Shock

Nail blanch test; Capillary refill time

McGrath JL, Bachmann DJ. Vital signs measurement. In: Roberts JR, Custalow CB, Thomsen TW, eds. Roberts and Hedges' Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Philadelphia, PA: Elsevier; 2019:chap 1.

Schoener B, Wagner MJ. Hand injuries. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 42.

Swartz MH. The peripheral vascular system. In: Swartz MH, ed. Textbook of Physical Diagnosis: History and Examination. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 15.

Updated by: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.