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Priapism / Prolonged Erection / Recurrent Priapism

Priapism is an abnormal sustained erection, classified as either low flow or high flow priapism. In patients with low flow priapism, there is obstruction to venous outflow. In the genesis of the low flow state, continued arterial inflow in the absence of venous outflow results in intracavernosal pressures in the erection chamber that prevent further blood from entering. Thus low flow priapism is a compartment syndrome associated with the patient having a sustained erection without arterial inflow. This irony is very confusing to most healthcare professionals as well as the lay public who often joke about erectile capability.

An erection that is sustained without the patient’s permission up to 4 hours is considered a prolonged erection. The diagnosis of low flow priapism is established by the history of an erection persistent beyond 4 hours. Since arterial inflow is usually absent, the tissue lacks oxygen and the penis becomes painful. This is a medical emergency that must be treated promptly to avoid permanent erection tissue damage and erectile dysfunction. In low flow priapism, the chamber that surrounds the urinary passageway (corpus spongiosum) is not erect, so the physical examination reveals a hard erection shaft and soft glans penis.

Mandatory laboratory tests assess for the presence or absence of arterial flow in the erection chamber. A needle can be placed in the side of the shaft of the penis, blood can be withdrawn, and the sample sent for oxygen content. In addition, an ultrasound study can localize the erection artery and verify if there is flow within. Other laboratory tests that can help establish the cause of the artery blockage include hemoglobin, hematocrit and testing to see if the patient has sickle cell disease. Certain drugs such as trazedone, heparin and some anti-psychotic drugs are associated with priapism.

The most common reason for priapism is intracavenosal self-injection. Prior to initiating home self-treatment, careful in office training programs are mandatory in order to minimize the chance of priapism. Patients on self-injection therapy need to be cognizant of priapism.

It is important to give patients with low flow priapism the opportunity to carefully weigh the risks and benefits of all treatment options, despite the emergent situation.

In contrast, high flow priapism is an abnormal erection associated with unregulated persistent blood flow into the erection chamber. This is commonly a result of blunt trauma to the perineum in which the abrupt force lacerates the erection artery. Distinct from low flow priapism, high flow priapaism is not associated with lack of oxygen, as proven by blood tests and Doppler ultrasound, and therefore is not a medical emergency.

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