A black finger bruise is a bruise underneath the nail, and the treatment depends on the specifics of the finger injury. If only a small piece of black under the nail, finger swelling is not very obvious can not be dealt with or pressure wound 1 day after the use of hot towels on the finger, so that the bruises better dissipate. If there is too much blood under the nail and the finger is swollen and painful, you can make a small cut in the nail to let the blood flow out, and then disinfect and bandage the wound, after the blood dissipates, the nail may become empty, and you need to wait for the new stent to grow to return to normal.