Bruising of the nails is mainly due to localized blood pooling after injury, and when the bruising is absorbed and subsides, there will be no cavities under the nails. When surgery in trauma or crush injuries lead to capillary rupture bleeding under the nail, followed by blood pooling bruising, usually more limited, the extent of bruising is mainly related to the site of injury. In most cases, bruising of the nail will not compress the soft tissue underneath the nail and will not cause necrosis of the surrounding tissues due to the bruising. Therefore, when the bruise absorbs and subsides, there will not be a hole under the nail. In the case of bruised nails after finger trauma, it is recommended to go to the hospital to see if there is any other trauma to the finger besides direct bruising, such as a fracture of the phalanx.