This is often caused by the following reasons: first, trauma to the nail, when the nail is squeezed or collision, will lead to the nail bed capillary rupture, it will cause under the nail bruising. Don’t worry too much, you can apply cold compresses locally. At the same time, take some oral hemostatic drugs and lift your fingers upward to prevent continued blood seepage. However, if the bruise is more, you need to go to the hospital for treatment, and if necessary, cut and bleed. Second, there are other possibilities, such as reduced platelets, which may also lead to subxiphoid bruising. Third, abnormal fibrinogen can also lead to subxiphoid bruising. Fourth, some special diseases, such as hemophilia, can cause subxiphoid bruising. Therefore, if you have subxiphoid bruising, you need to go to the hospital for surgical treatment in a timely manner, and your doctor will complete the relevant tests and identify the cause.