How can there be bruises on the legs In general, there are often the following causes: 1. The patient has a local fall, which can cause the rupture of the subcutaneous capillaries, and blood seeps into the skin and tissue interstices, manifesting as subcutaneous bruises. At this time, due to the small amount of capillary blood, often can stop bleeding on its own. If local ice is used to promote capillary constriction and reduce the extravasation of blood, hot ointment pack is given after 24 hours to promote the absorption of the bruise with better therapeutic effect; 2. After local blood sampling, the patient does not have enough time to compress, causing blood to continue to extravasate along the eye of the needle, resulting in local bruising. This is mostly seen when femoral artery puncture is performed and the patient compresses the puncture site for less than 15 minutes after the puncture is completed. The pressure in the femoral artery is high, and blood seeps down the eye of the needle into the subcutaneous tissue, causing bruising of the skin.