Priapism is a term used to describe a prolonged erection lasting
more than 6 hours, usually not associated with sexual activity,
and frequently starting during sleep. This descriptive term is derived
from the Greek god of fertility, Priapus, whose statues depict him
with an erection. An erection lasting over 6 hours is associated
with changes that can prevent normal detumescence.
There are two types of priapism and early classification is essential
for appropriate treatment. Low-flow (ischemic) priapism is the more
common form. Although frequently idiopathic, there are several specific
causes that can require specific therapy. Because progressive tissue
damage occurs, success of treatment is dependent upon rapid reversal
of the ischemia in these patients, who usually are late in seeking
help.1,2 The second type of priapism is high-flow (nonischemic)
priapism. This is usually due to blunt trauma of the corpora with
an arterial rupture giving rise to an arteriovenous fistula. High-flow priapism is uncommon but important
to differentiate from low-flow priapism. Treatment of high-flow
priapism is not an emergency but requires immediate follow-up. Although
ischemic damage does not occur with high-flow priapism, erectile
dysfunction is still reported in about 20 percent of patients after
There is a significant potential for disability in low-flow patients
because either treatment fails to reduce the erection or erectile
dysfunction occurs, even if the reduction is successful. Erectile
dysfunction can be as high as 50 percent in low-flow priapism.1,3 For
this reason patients should be made to understand that even with
treatment, the outcome is uncertain. Legal implications are serious
in this group of patients and full discussion with appropriate documentation
in the medical record as treatment progresses is warranted.
The need for prompt recognition and treatment of low-flow priapism
has been demonstrated in both experimental and clinical series.
In animal models, interstitial edema occurs in 12 hours, endothelial
damage by 24 hours, and smooth-muscle changes
within 48 hours.4 In a series of patients with
priapism secondary to self-injection for erectile dysfunction, patients under
36 hours duration were usually successfully treated with
aspiration and alpha-adrenergic drugs with no resulting
fibrosis. No patients responded to alpha-adrenergic therapy and
fibrosis was found in all cases if the priapism was present for
over 36 hours, even if reduction of the priapism was successful.5 Others
have confirmed histomorphological changes within 6 to 8 hours
of ischemia in the corpora cavernosa structures.6
The penis is primarily composed of the paired corpora cavernosa
and the corpus spongiosum (Figure 126-1). An incomplete septum between
the corpora cavernosa allows flow between them. The corpus spongiosum,
which surrounds the urethra, terminates in the glans of the penis.
A superficial and deep neurovascular bundle is located on the dorsal
surface of the penis.
Cross-section of the penis demonstrating the ...
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