|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
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.