The main reasons for bruising include the following: First, it is due to the disorder of the coagulation system. The lack of certain coagulation factors in the coagulation system or hypersplenism or splenomegaly, which leads to excessive platelet destruction and thus reduces the number of platelets, can cause abnormalities in the coagulation system and lead to bruising. Secondly, it is considered to be due to the dysfunction of the body’s immune system, which leads to increased blood permeability, increased vascular exudation, and blood spilling out of the veins, which leads to localized bruises on the body. If you have bruises on your body, you need to go to the hematology department of the hospital to have blood routine, coagulation system and immune system function examination to clarify the cause.