Blanch (medical)

{{Short description|Whitish appearance of the skin}}

{{Missing information|difficulty of observation in people with dark skin|date=December 2020}}

When skin is blanched, it takes on a whitish appearance as blood flow to the region is prevented. This occurs during and is the basis of the physiologic test known as diascopy.

Blanching of the fingers is also one of the most clinically evident signs of Raynaud's phenomenon.{{cite journal |last1=Cracowski |first1=Jean-Luc |last2=Roustit |first2=Matthieu |title=Human Skin Microcirculation |journal=Comprehensive Physiology |date=17 January 2011 |volume=10 |issue=3 |pages=1105–1154 |doi=10.1002/cphy.c190008 |url=https://onlinelibrary.wiley.com/doi/10.1002/cphy.c190008 |access-date=16 October 2022 |publisher=Wiley |pmid=32941681 |isbn=9780470650714 |s2cid=221788791 |language=en|url-access=subscription }}

Blanching is prevented in gangrene as the red blood corpuscles are extravasated and impart red color to the gangrenous part.