Priapism is defined as erection that lasts longer than 6 hours. Such a prolonged erection causes physiological changes by 6 hours, cellular damage by 24 hours, and fibrosis by 36 hours, resulting in permanent erectile dysfunction.
Low-flow (ischemic) priapism is the more common form of priapism.
Causes of low-flow priapism fall into the following categories:
Hematologic (eg, sickle cell, leukemia)
Pharmacologic – Adverse effects (eg, psychiatric medications)
Pharmacologic – Therapeutic (eg, oral erectile medications, intracavernous injections)
Others (eg, surgical, traumatic, neurogenic, infectious)
Management of ischemic priapism should achieve resolution as promptly as possible. Initial treatment is therapeutic aspiration with or without irrigation of the corpora. If this fails, intracavernous injection of sympathomimetic drugs is the next step.
High-flow priapism is rare and is usually a result of blunt trauma to the corpora cavernosus resulting in arteriovenous fistula. The treatment for high-flow priapism is surgical and is not discussed in this article.
The erectile tissue within the corpora contains arteries, nerves, muscle fibers, and venous sinuses lined with flat endothelial cells, and it fills the space of the corpora cavernosa. The cut surface of the corpora cavernosa looks like a sponge. There is a thin layer of areolar tissue that separates this tissue from the tunica albuginea. Blood flow to the corpora cavernosa is via the paired deep arteries of the penis (cavernosal arteries), which run near the center of each corpora cavernosa. See the image below.
For more information about the relevant anatomy, see Penis Anatomy.