Always bulging when the needle is withdrawn may be a symptom caused by the needle not being inserted properly, vasculitis and other reasons. 1. The needle is not inserted properly: if the needle only passes through the wall of the blood vessel and does not penetrate deeply into the blood vessel; or due to the poor elasticity of the skin of the elderly, the needle may cut the wall of the blood vessel; or due to the needle is not fixed; in these cases, the blood leaks out from the vein, thus leading to the bulging of the bag. 2. Vasculitis: because of the indwelling needle sometimes induces phlebitis, the specific manifestation is a vein bulging out of the hand, painful and hard to the touch, may be the indwelling needle in the skin stays too long, which leads to the phenomenon of bulging. When the patient has an indwelling needle, it is necessary to avoid external impact, so as not to cause adverse consequences, the indwelling needle should not be left for too long, and when there are abnormalities in time to seek medical attention.