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Priapism is a painful and potentially harmful medical condition in which the erect penis (erection) does not return to its flaccid state (in the absence of both physical and psychological stimulation) because blood cannot exit the tissues or vessels of the penis. Potential complications include ischemia (swelling), clotting of the blood retained in the penis, and damage to the blood vessels of the penis which may result in an impaired erectile function or impotence. In extreme cases, the condition may result in gangrene, which may necessitate amputation. Treatment is usually hydraulic, withdrawing a part of the trapped blood.
Priapism can be caused by certain drugs, such as anti-depressants and Viagra, and can be a possible sign of a spinal injury. Conditions that thicken the blood, or affect the red blood cells, such as leukaemia and sickle-cell anaemia can cause this problem.
The name comes from the god Priapus, referring to that god's most notable attribute.
The female counterpart is known as clitorism.
See also paraphimosis