There are two types of priapism. The first type, which is less common, is called high flow priapism. And it's usually a process that results after some type of trauma to the penis. This type usually goes away on its own. And the oxygen that's trapped in the penis is usually highly oxygenated. It's oxygen, rich blood, and therefore is not considered a true emergency. And there's usually less pain associated with it. The second type is the most common type. This is called either ischemic, priapism, or low flow priapism. Those are two terms for the same condition. Usually the penile shaft is rigid while the teper, the head of the penis is soft. This type can also start and stop over time. It's this low flower ischemic priapism that's considered a medical emergency and needs to be addressed urgently so that the tissues in the penis can stay healthy.