Priapism may be defined as an involuntary erection that lasts for more than 4–6 h. The condition may be spontaneous or secondary to intracavernous pharmacotherapy. Spontaneous priapism may be idiopathic or associated with blood disorders such as sickle cell anemia, leukemia or other malignancies (

Figure 34).

After 4–6 h, a persistent erection usually becomes painful, but late presentation is not uncommon because of embarrassment.

Initial therapy involves corporeal aspiration and injection of adrenergic vasoconstrictor substances such as phenylephrine or metaraminol (Aramine®). Because these potent vasoactive agents frequently enter the circulation after intracorporeal injection, blood pressure should be carefully monitored during therapy.

Vasculogenic Causes of ED
Neurogenic Causes of ED
Endocrinological Causes of ED
Priapism and Postpriapism ED
Psychogenic Causes of ED

Although pharmacotherapy with aspiration and injection of vasoactive agents is often successful within 6–12 h of onset of priapism, beyond that time period the efficacy of any therapy is rapidly diminished.

Initial high-flow priapism is followed by lower flow and progressive deoxygenation of the corpora. In these later cases, aspiration of the corpora reveals dark deoxygenated blood. Progressive ischemia to the intracorporeal smooth muscle renders the helicine arteries and walls of the trabecular spaces progressively less capable of developing sufficient vasoconstriction necessary to restore and maintain flaccidity.

The consequence of untreated priapism or priapism unresponsive to therapy is the development of corporeal fibrosis. This results in erectile dysfunction which is difficult, and sometimes impossible, to treat. Even insertion of a penile prosthesis may be technically difficult in such cases because the fibrosis renders dilatation of the corporeal space problematical.