In most cases of priapism the cause isn't discovered. And the medical term for that is idiopathic when the cause is not identified. But when the cause is discovered, certain blood disorders can predispose to Priapism. And the most common one is sickle cell trait or sickle cell disease, but other blood disorders, including certain leukemias and multiple myeloma can be associated with Priapism. In other cases, an acute spinal cord injury can cause Priapism and rarely, cancer, that has spread from somewhere else to the penis, can cause Priapism. These are some of the varied causes of Priapism when the cause is identified. But again, most commonly the cause is not known.