Drawing blood green is due to the end of the blood draw, the needle pulled out when the local blood vessels are not well pressed, resulting in bleeding or oozing blood on the surface of the blood vessels and the formation of. So after drawing blood, early must use cotton balls or cotton swabs to the eye of the needle place pressure, at the same time in the process of pressure can not be rubbed back and forth or sliding, otherwise it will also lead to the drawing of blood place bleeding. Early after bleeding, a lump will form and is painful, need to immediately use ice or cold towel on the surface of the cold compress, can effectively reduce the further expansion of bleeding, or reduce the surrounding tissue fluid further oozing. If the lump is fully formed after 1-2 days, apply warm compresses with a hot towel to the surface, in order to accelerate the blood circulation around the area and make the bruise go away more quickly.