Keeping it Straight: Priapism

To start off your week, we have a quick and handy guide to a sensitive topic: priapism.  Second year medical student Raevti Bole takes us through the basics with this Quickhit:

Quickhit

What is it?

A prolonged (usually between 4-6 hours), painful erection not associated with sexual desire. It’s not a very common complaint in the ED, but if someone does present with this, it’s considered a true urological emergency.

Pathophysiology

There are two types of priapism: High-flow priapism (non-ischemic), and low-flow priapism (ischemic). Only ischemic priapism is an emergency.

In an emergency situation, blood cannot exit the penis. This causes oxygen levels to drop leaving the patient in pain and the cavernosal tissue at risk of fibrosis and then necrosis (time dependant).

Treatment

Time is critical, because longer you wait to treat, the higher the risk of future erectile dysfunction in a patient with ischemic priapism.

Diagnose: first determine what type of priapism it is (physical exam, blood gas measurement, Ultrasound, Blood test, toxicology)

Treat: Aspiration therapy (including saline flush), medication, and finally surgery if all else fails. Also treat primary causes of low-flow priapism, such as giving O2 and hydration to sickle cell anemia patients.

Complications

Erectile dysfunction

Penile necrosis and disfigurement

 

Read below to get more information!

 Pathophysiology

In a normal erection the corpora cavernosa, the corpus spongiosum, and the glans penis are all erect. When a patient has priapism, only the corpora cavernosa of the penis is engorged with blood leaving the ventral penis (looks flat) and glans penis flaccid since the corpus spongiosum is not full. In an emergency situation, the blood cannot exit the penis and the cavernosal tissue is at risk of ischemia, fibrosis and then necrosis.

Priapism1

Image courtesy of Vilke, G. M. et al. “Emergency Evaluation and Treatment of Priapism.” Journal of Emergency Medicine 26.3 (2004): 325-29.

Types of Priapism:

High-flow priapism (non-ischemic):

Secondary to trauma to the genitals, pelvis or perineum. This condition is caused by excessive arterial blood flowing directly into the penile sinusoidal spaces, then draining out slowly. It is not considered a true emergency requiring immediate treatment, and is less common than low-flow priapism.

Low-flow priapism (ischemic):

Caused by a number of conditions such as sickle-cell anemia, drugs, injection therapy for erectile dysfunction, leukemia, anticoagulants, spinal cord injury, etc. Often the cause is unknown. Low-flow priapism presents with pain, unlike high-flow priapism, and is an emergency.

Treatment

Time is critical, especially because patients with an erection lasting over 4 hours should seek immediate medical care, but often they do not go to a doctor until the condition has lasted about 24 hours. The longer they wait, the higher the risk of future erectile dysfunction.

Diagnose: determine what type of priapism it is

Physical exam: Low flow priapism results in a very rigid penis that cannot be bent. High-flow priapism results in a slightly more flexible penis that can be bent. Also, if there is a recent history of trauma to the genital area, high-flow priapism can be suspected and confirmed with another diagnostic method.

Blood-gas measurement: Aspirate blood from one corpus cavernosum (since the septum in between is incomplete, you will get blood from both corpora). Blood gas values near arterial blood indicate high-flow priapism, while values near venous blood indicate low-flow. Looking simply at color, bright red blood is closer to arterial blood whereas darker blood may be oxygen-deprived. Also check for acidosis, as pH under 7.10 is a clue that treatment should begin.

Ultrasound: color duplex ultrasound is useful in verifying the presence of trauma causing an arterial-sinusoidal shunt in the penile tissue.

Blood test: check RBC and platelets for sickle-cell anemia or other hematologic conditions

Toxicology test: screen for the presence of drugs in the system, prescription or otherwise. Trazodone (anxiolytic, hypnotic) use has been associated with priapism, as well as agents used in intracavernous pharmacotherapy (phentolamine, prostaglandin E1).

Treat:

Low-flow priapism requires immediate attention.

  1. Anesthetize penis and aspirate 10-15 ml of blood from the corpora using a 19 or 21-gauge butterfly needle.
  2. Replace the blood with an equal amount of saline. Repeat the flushing process until aspirate from the corpora is bright red (arterial) in color.
  3. If condition persists, inject with 1-3 200 mg boluses of alpha-adrenergic receptor agonist such as phenylephrine (each bolus separated by ten minutes) while monitoring patient’s blood pressure. Epinephrine can also be used but can cause worse systemic side effects such as tachycardia and arrythmia. Metaraminol is not used any more because of the risk of severe hypertension.
  4. If non-operative treatment fails, patient will have to be admitted for urological surgery immediately. A shunt will have to be created between the engorged corpora cavernosa and the glans penis or corpus spongiosum.
  5. Sickle cell anemia patients usually do not require invasive medical aid, and will find a decrease in symptoms from aspiration, hydration, oxygenation and pain management.

High-flow (non- ischemic) priapism often resolves on its own with no risk of ischemic damage to penile tissue, so telling the patient to simply apply ice and pressure to the perineum may be the best way to treat the condition while waiting for it to resolve.

 Submitter: Raevti Bole

References

Cherian, J. “Medical and Surgical Management of Priapism.” Postgraduate Medical Journal 82.964 (2006): 89-94.

Montague, Drogo K., and Milton M. Lakin. “Priapism.” Urology Secrets. By Martin I. Resnick and Andrew C. Novick. Philadelphia, PA: Hanley & Belfus, 2003. N. pag. Print.

“Priapism: Prolonged Erection.” Mayo Clinic. Mayo Foundation for Medical Education and Research, n.d. Web. 14 Aug. 2013

Vilke, G. M., Richard A. Harrigan, Jacob W. Ufberg, and Theodore C. Chan. “Emergency Evaluation and Treatment of Priapism.” Journal of Emergency Medicine 26.3 (2004): 325-29.

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