It results from severe vasospasm in response to a temperature change, causes marked and typically sharply demarcated pallor of one or more digits. As circulation recovers, the digit becomes blue (cyanotic) and then bright red because of rebound hyperaemia — the tri-phasic response. 

Raynaud ’s is commoner in females than males. In young women the condition is often a harm less nuisance, requiring warm gloves and sometimes vasodilators. Its onset for the first time in older people warrants investigation. Raynaud ’s may also be part of a systemic autoimmune disorder (rheumatoid arthritis, systemiclupus erythematosus, or systemic sclerosis), and it occasionally leads to necrosis. When associated with rheumatoid disease, Raynaud ’s can be extremely severe and requires specialist referral. It can also occur in people who use vibrating tools. Roughly two out of three patients with primary Raynaud ’s phenomenon have spontaneous resolution of their symptoms (Spencer - Green, 1998).