venipuncture site, remember that a vein will feel bouncy and will have a resil­iency to it, and an artery will feel firmer and will pulsate. In the event of an acci­dental artery puncture, the blood will appear bright red instead of dark red. The flow will usually be more forceful and may pulsate. If this occurs, immediately remove the tourniquet, withdraw the needle, and apply firm pressure for at least 5 minutes. Once the bleeding has stopped, apply a taut gauze dressing. Instruct the patient to keep the arm relatively still for a short period to minimize the flow of blood. This will help prevent a hematoma. A hematoma occurs when blood collects under the skin, forming a black and blue mass. A hematoma can form as a result of inserting a needle through a vein or an artery. Fragile veins can also break or leak, causing hematoma formation. To prevent accidental arterial punc­ture, do not select a vein that lies over or close to an artery. When an accidental arterial puncture does occur, stop the bleeding, then immediately notify a nurse (or supervisor, in the case of outpatient draws).