This refers to unwanted, inappropriate (unrelated to sexual activity), persistent,
painful erection. Priapism is distinguished from normal erection by absence
of tumescence of the glans. It may be idiopathic, associated with sickle cell
disease, chronic granulocytic leukemia, spinal cord injury, or secondary to
injection of vasodilator agents (e.g. PGE1) into the penis, drugs (e.g. trazadone),
thrombosis of the penile veins or to adrenergic-mediated mechanism for detumescence.
In priapism of sickle cell disease, the corpora cavernosa are usually engorged
and the glans and corpus spongiosum are spared. In a minority however, tricorporal
priapism occurs. Priapism, especially tricorporal, may eventuate in impotence.