Hands suddenly green a piece, is the hands of subcutaneous bleeding, that is, blood from the blood vessels to the blood vessels outside, hands suddenly green a piece of a variety of reasons, the most likely are: First, thrombocytopenia disease, if a person suffers from thrombocytopenia disease, due to the human body’s hemostatic function decline in unintentional minor collision, there may be hands suddenly green a piece of the situation. Second, coagulation disorders, whether it is vitamin K deficiency, or other diseases caused by decreased activity of coagulation factors, due to the decline in the body’s coagulation function, there will also be a sudden green piece of the hand. Third, vitamin C deficiency, because vitamin C can increase the densification of capillaries, reduce the permeability of capillaries, if vitamin C deficiency, the permeability of blood vessels will increase, in the case of minor trauma will also appear bleeding, resulting in the hands of a sudden green piece. Therefore, if there is a sudden piece on the hand, it is best to go to the hematology department of the hospital to test the blood routine and coagulation routine.