What is the pathophysiology of low-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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Low-flow priapism may be due to any of the following:

  • An excessive release of neurotransmitters
  • Blockage of draining venules (eg, mechanical interference in sickle cell crisis, leukemia, or excessive use of intravenous parenteral lipids)
  • Paralysis of the intrinsic detumescence mechanism
  • Prolonged relaxation of the intracavernous smooth muscles (most often caused by the use of exogenous smooth-muscle relaxants such as injectable intracavernosal prostaglandin E1)

Prolonged low-flow priapism leads to a painful ischemic state, which can cause fibrosis of the corporeal smooth muscle and cavernosal artery thrombosis. The degree of ischemia is a function of the number of emissary veins involved and the duration of occlusion. Light-microscopy studies conducted early on demonstrated that corporeal tissue becomes thickened, edematous, and fibrotic after days of priapism.

Further studies with electron microscopy have demonstrated trabecular interstitial edema after 12 hours of priapism and destruction of sinusoidal endothelium, exposure of the basement membrane, and thrombocyte adherence after 24 hours of priapism. At 48 hours, thrombi were evident in the sinusoidal spaces and smooth-muscle cell histopathologic findings varied from necrosis to fibroblast-like cell transformation. Priapism for longer than 24 hours is associated with the likelihood of permanent impotence.

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