Respected Sir, hi I evaluated your query thoroughly. Regarding flat blue painless vein there are 2 possibilities : 1.Varicosity of Saphenous tributary 2.Non-specific idiopathic appearance of vein remotely concerned with minute undetectable perfusion disturbance. Can undergo Doppler Ultrasound for final diagnosis . Hope this clears your query. Thanks for using Health care Magic. Regards Take care bye Wishing you happy healthy life ahead.