Blanching on the skin refers to a temporary lightening or whitening of its color. This occurs when external pressure squeezes blood from tiny capillaries beneath the skin’s surface. Upon release, blood quickly refills these vessels, allowing the skin to regain its usual hue.
Recognizing Blanching
When skin blanches, it typically appears noticeably paler, often whitish, depending on natural skin tone. A simple “blanch test” involves gently pressing a finger onto the skin for a few seconds. Upon removing pressure, healthy skin shows a pale area that quickly returns to its original color. This rapid return indicates normal blood flow and capillary refill. If an area remains red or discolored even with pressure, it is non-blanching and suggests a different underlying issue.
Common Reasons for Blanching
Blanching is a visible manifestation of vasoconstriction, a physiological process where blood vessels narrow. This narrowing reduces blood flow, causing the skin to appear pale. Common and often harmless reasons for skin blanching include direct pressure, such as leaning against a hard surface or wearing tight clothing. Exposure to cold temperatures also causes blood vessels to constrict to conserve body heat, leading to paleness, particularly in extremities. Emotional responses like fear or shock can trigger a redirection of blood flow away from the skin to internal organs, resulting in paleness.
When Blanching Indicates a Problem
While often a normal and healthy response, certain blanching patterns or the absence of normal blanching can signal underlying health concerns. Prolonged blanching, where skin remains pale after pressure is removed, may indicate compromised blood flow or poor circulation. Conversely, non-blanching redness, where skin stays red or discolored when pressed, is a significant sign of leaked blood or tissue damage. This non-blanching characteristic is particularly concerning in conditions like pressure injuries (bedsores), where it can be an early indicator of impaired blood flow and impending ulcer formation.
Conditions such as severe frostbite, Raynaud’s phenomenon, and arterial insufficiency can also present with abnormal blanching or discoloration due to significant blood flow restriction. In Raynaud’s, small blood vessels in the fingers and toes constrict excessively in response to cold or stress, causing the skin to blanch, then turn bluish, and finally red. If blanching is prolonged, accompanied by pain, numbness, coolness, or if the skin does not return to its color, or if there is persistent non-blanching redness, seek medical attention. These symptoms may require professional evaluation and treatment.