Priapism is a persistent and often painful erection of the penis that occurs without sexual stimulation or desire and lasts for at least four hours. It is a medical emergency and requires prompt treatment as it can cause permanent damage to the erectile tissue. There are two main types of priapism. First, there is ischemic priapism, which is often associated with sickle cell disease. The second type is non-ischemic, mostly seen in settings of prior trauma or instrumentation of the penis. Symptoms include a prolonged erection lasting at least four hours. There is also pain, and color change to the penis.