Priapism

EM Emergency Medicine Priapism Apr 06, 2018 Nikolai Butki, DO, MPH

Nikolai Butki, DO, MPH, Associate Professor of Emergency Medicine Michigan State University College of Osteopathic Medicine, and Associate Residency Program Director, Emergency Medicine, McLaren Oakland, Pontiac, MI

SummaryPathophysiology of normal erection: corpora cavernosa — 2 areas of glandular tissue in penis; surrounded by fibrous layers; outermost layer Buck’s fascia; inner layer tunica albuginea; normal blood flow — circumflex veins run between layers of corpora cavernosa; during erection, increased arterial supply engorges corpora cavernosa, compressing circumflex veins and decreasing outflow; detumescence — normal erection dissipates after cessation of sexual stimulation or ejaculation; decrease in arterial blood supply decompresses circumflex veins; allows for rapid drainage of blood supply of corpora cavernosa

Pathophysiology of low-flow (ischemic) priapism: arterial blood supply does not decrease; circumflex veins do not decompress; corpus spongiosa does not engorge with blood; dysfunction of flow mechanism limited to corpora cavernosa; compromised blood flow results in continued stasis of blood within the corpora cavernosa; static blood becomes hypoxic and acidotic; ischemia ensues, causing pain

Pathophysiology of high-flow (nonischemic) priapism: disruption of arterial supply (usually after trauma) leads to arterial bleed into corpora cavernosa; drainage of circumflex veins remains adequate, resulting in local swelling; no static or hypoxic blood; treatment not as emergent as for ischemic priapism

Distinguishing high-flow from low-flow priapism: blood gas of extracted blood — normal in nonischemic priapism; low PaO2, low pH, and high PaCO2 in ischemic priapism; imaging — angiography, computed tomographic angiography, or magnetic resonance imaging; clinical picture — high-flow priapism generally not painful; secondary to trauma; unilateral and focal swelling; bilateral swelling in ischemic priapism

Treatment for priapism: penile nerve block — ring block (inject local anesthetic circumferentially) at base of penis; local nerve block involves local anesthesia of dorsal nerves; corpora cavernosa decompression — decompress circumflex veins on one side, to facilitate drainage; use 18G or 19G butterfly needle directed at 3 o’clock or 9 o’clock position to avoid unwanted injury to urethra (along ventral side of penis) or neurovascular bundle (along dorsal side of penis); aspirate directly or drain into basin; if drainage unsuccessful, irrigate with saline to remove clots; alpha-adrenergics — injected if drainage or irrigation fails; phenylephrine most commonly used at dosage of 200 µg; decompresses veins; urology consult — always necessary for priapism, even if drainage performed in emergency department; outcomes potentially poor with ischemia; evidence-based recommendations — no official consensus or level I recommendations for management of priapism; in general, evidence-based reviews recommend aspiration and injection of alpha-adrenergic agents

Readings

Podolej GS et al: Emergency department management of priapism [digest]: Emerg Med Pract. 2017 Jan 22;19(1 Suppl Points & Pearls):S1-S2; Shigehara K et al: Clinical Management of Priapism: A Review. World J Mens Health. 2016 Apr;34(1):1-8; Martin C et al: Effect of phenylephrine and terbutaline on ischemic priapism: a retrospective review. Am J Emerg Med. 2016 Feb;34(2):222-4.