How is low-flow priapism differentiated from high-flow priapism?

Updated: Dec 26, 2019
  • Author: Osama Al-Omar, MD, MBA, FACS, FEBU; Chief Editor: Edward David Kim, MD, FACS  more...
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To provide appropriate treatment, physicians must differentiate between low-flow and high-flow priapism. This is accomplished by taking a thorough history, performing a careful physical examination, and measuring the oxygen content of blood within the corpora cavernosa by penile blood gas (PBG) analysis (see Workup).

Low-flow priapism, which constitutes the large majority of cases, is characterized by a rigid, painful erection; ischemic corpora, as indicated by dark blood upon corporeal aspiration; and no evidence of trauma. The history may reveal an underlying cause, such as sickle cell disease or use of intracavernosal or oral agents for treatment of erectile dysfunction, or other medications known to be associated with priapism (see Etiology).

Patients with high-flow priapism typically have a history of blunt or penetrating trauma to the penis or perineum, resulting in a fistula between a cavernosal artery and the corpus cavernosum. Clinically, high-flow priapism is characterized by a painless erection; tumescence is typically less marked than in low-flow priapism.

The presence of bright red blood during aspiration is a helpful but not pathognomonic finding of high-flow priapism. PBG findings approximate normal arterial values. Penile duplex ultrasonography with angiographic confirmation helps to identify and locate these fistulae.


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