What Can Cause Priapism?

Priapism is defined as penile erection disease that is characterized by its prolongation and by the absence of stimulation or sexual excitement. It usually occurs with a lapse of more than 6 hours and typically involves only the cavernous bodies resulting in the dorsal erection of the penis with flaccid gland and ventral penis.

Some researchers have mentioned time as a criterion to identify this disorder, they have defined in a 4-hour interval, based on clinical experience that has shown that a lapse greater to this one associates serious consequences for sexual function.

Classically this disorder has been divided into two types, very different from each other, with different physiopathological mechanisms and different treatments. There are 2 types of priapism: ischemic or veno occlusive and non-ischemic or arterial. The first represents the most common form of presentation and is more severe, while the non-ischemic one does not represent a urological urgency.

What can Cause Priapism?

What can Cause Priapism?

The causes of priapism can be primary, secondary or idiopathic. Priapism with primary etiology is not accompanied by an organic disorder that is responsible for the prolonged erection, so in this case physical and psychological causes are indicated. The secondary is induced by factors that directly or indirectly affect the penile erection, for example: sickle cell anemia, leukemia, coagulopathies, and thrombosis of cavernous bodies, among others.

Finally, the idiopathic cause as its name says, it does not present an apparent cause or physiopathological mechanism that explains it. Among the main causes that have traditionally been described for this disorder are hematologic dyscrasias, especially sickle cell anemia, some leukemias and the sickle cell trait. The penile and perineal injuries usually cause priapism in some cases. Last but not least, there is pharmacotherapy, which has been seen increasing the number of cases after the introduction of vasoactive drugs intravenously as erectile dysfunction therapy. From a physiopathological point of view, two types of priapism are described, the high-flow or non-ischemic type and the low-flow or ischemic type. The priapism of high flow is defined by an increase in arterial blood flow in the cavernous bodies of the penis, which results in an erection maintained with good tissue oxygenation. This increase in flow is usually secondary to the laceration of the cavernous artery due to blunt or penetrating trauma that creates an abnormal communication between the injured artery and the corpus cavernosum. This blood hyper flow carries a higher partial pressure of O2 that stimulates the production of nitric oxide that relaxes the smooth muscle of arterioles, dilates them and fills the sinusoidal spaces.

On the other hand, low flow priapism is associated with a severe decrease in the venous drainage of the cavernous bodies. It is usually due to a partial or complete obstruction in the drainage that prevents the entry of arterial blood and generates acidosis and ischemia. It is the most common form of presentation and behaves like a compartment syndrome with excessive pressure increase in the cavernous bodies.

In low flow priapism or occlusive vein, the spectrum of symptoms and signs is analogous to any of those who are in a compartment syndrome.

There is a prolonged painful erection, in which the rigid cavernous bodies are perceived and painful to palpation. Histological studies show the presence of edema and thickening up to 12 hours, presence of adhesions and thrombi until 24 hours and more than 48 hours has seen smooth muscle necrosis and proliferation of fibroblasts resulting in fibrosis and calcification and a tissue reperfusion syndrome that releases a large number of free radicals that cause more necrosis and fibrosis. This in turn is associated with irreversible injury of the cavernous tissue and with loss of erectile function, which is why it is considered a medical-urological emergency.

In high-flow priapism, the cavernous bodies are not completely rigid or painful.


Priapism represents a rare disease, with a relatively low incidence for the general population. However, the early recognition of this disease is of great importance, since it has been seen that fatal consequences for the patient’s sexual life increase the longer the clinical presentation and the later the treatment.

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Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:March 26, 2019

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