Priapism symptoms vary depending on the type of priapism. The two main types of priapism are ischemic priapism and nonischemic priapism. Ischemic priapism Ischemic priapism, also called low-flow priapism, is the result of blood not being able to leave the penis. Blood is trapped in the penis because it cannot flow out of the veins of the penis or there is a problem with the contraction of smooth muscles within the erectile tissue of the penis. Ischemic priapism is the more common type of priapism and requires immediate medical care to prevent complications caused by not getting enough oxygen to the penile tissue. Signs and symptoms include: 
Erection lasting more than four hours or unrelated to sexual interest or stimulation
Rigid penile shaft, but the tip of penis (glans) is soft
Progressively worsening penile pain
 Stuttering priapism — also called recurrent or intermittent priapism — is a form of ischemic priapism. An uncommon condition, stuttering priapism describes repetitive episodes of prolonged erections and often includes episodes of ischemic priapism. It occurs more often in males who have an inherited disorder characterized by abnormally shaped red blood cells (sickle cell disease). Sickle cells can block the blood vessels in the penis. In some cases, the condition starts off with unwanted and painful erections of short duration and might progress over time to more-frequent and more-prolonged erections. Stuttering priapism may begin in childhood. Nonischemic priapism Nonischemic priapism, also known as high-flow priapism, occurs when blood flow through the arteries of the penis isn't working properly. However, the penile tissues continue to receive some blood flow and oxygen. Nonischemic priapism often occurs due to trauma. Signs and symptoms include: 
Erection lasting more than four hours or unrelated to sexual interest or stimulation
Erect but not fully rigid penile shaft
Usually not painful
