Hunter Wessells, MD, FACS
Brad Figler, MD
BASICS
DESCRIPTION
• Prolonged, usually painful erection, occurring in the absence of sexual stimulation
– Named for Priapus, the Greek god of fertility who had an oversized, eternally erect penis
• Ischemic priapism (low-flow, veno-occlusive) is most common: Compartment syndrome of the erectile bodies causing ischemia, and ultimate necrosis of the cavernosal smooth muscle
• Nonischemic priapism (high flow, arterial) is less common: Uncontrolled arterial inflow into the cavernosal sinusoids without ischemia or necrosis of cavernosal smooth muscle
• Recurrent (Stuttering) priapism: Episodes are recurrent but of limited duration
• Refractory priapism: Persistent after surgical therapy
• Clitoral priapism (Clitorism): Described in case reports and usually presents as severe vulvar pain; associated with the use of antipsychotics:
– Management is conservative with removal of the inciting agent
• Priapism in children usually associated with leukemia or sickle cell disease
ALERT
A low-flow ischemic priapism is considered an emergency since early intervention improves the chances for proper erectile function after.
EPIDEMIOLOGY
Incidence
• It is suggested that 10% of patients with sickle cell disease experience priapism, either recurrent short episodes (stuttering priapism) or single prolonged episodes. A higher percentage of men with sickle cell disease may report past attacks, although not all of them requiring medical care
• Priapism is most common between ages 5 and 10 in boys and ages 20 and 50 in men
• Alprostadil intracavernosal injection for the treatment of erectile dysfunction associated with a 1% rate of priapism in clinical trials
• FDA data (2007): 93 cases due to PDE5 inhibitors (likely higher due to unreported cases)
Prevalence
N/A
RISK FACTORS
• Ischemic priapism
– Sickle cell, other hematologic disorders
Neonatal polycythemia, thalassemia
– Intracavernosal injection therapy (papaverine, phentolamine, prostaglandin E1)
– Prescription drugs
PDE5 inhibitors (sildenafil, others in class)
Hydralazine, guanethidine, α-adrenergics [eg, tamsulosin], psychotropics (risperidone, olanzapine, trazodone, SSRIs (fluoxetine bupropion), heparin, coumadin, erythropoietin, methylphenidate
– Illegal drugs: Cocaine, marijuana
– Poisonous venom, spinal cord injury
– Malignancy: Metastatic cancers (GU tumors most common), melanoma, leukemia
– Dialysis, TPN
• Nonischemic priapism: Straddle injury to the perineum or direct blow to the cavernosal bodies anywhere along the length
Genetics
Associated with genetic blood dyscrasias (sickle cell anemia, sickle cell trait, thalassemia) and Fabry disease
PATHOPHYSIOLOGY
• Ischemic priapism comprises the great majority of cases of prolonged erection
– Ischemic priapism is caused by a veno-occlusive phenomenon in which a variety of environmental factors lead to hypoxia, acidosis, and dysregulation of cavernosal smooth muscle relaxation leading to persistent veno-occlusion, a compartment syndrome, with absent further arterial inflow
– A feature of ischemic priapism is the ischemia reperfusion injury and oxidative stress that occurs after release of the ischemic insult
– Hematologic abnormalities generally cause a low-flow state with red blood cells sludging and veno-occlusion (sickle cell disease, thrombophilia, thalassemia, leukemic infiltration, splenism, erythropoietin, hemodialysis with heparin, total parental nutrition)
– Pharmacologic (α-adrenergic antagonist, intracavernosal injection, intraurethral alprostadil, antihypertensive medications, psychotropic medications)
– Neurologic (spinal cord injury, brain tumor, neurosyphilis)
– Neoplastic (local vs. metastatic, infiltration)
– Idiopathic
• Nonischemic priapism
– Unregulated arterial inflow due to traumatic injury to cavernosal artery or one of its branches with unimpeded arterial inflow to the corporal sinusoids
– Persisting fluid shear stress due to increased inflow leads to further vasorelaxation due to endothelial NO synthase activation
ASSOCIATED CONDITIONS
• Alcohol abuse, psychiatric disorders
• Attention deficit hyperactivity disorder (ADHD): Methylphenidate use
• Blood dyscrasias
• Cocaine abuse
• Epidural anesthesia and analgesia
• Hemoglobinopathies
• Hypercoagulable states
• Intracavernous or intraurethral ED therapy
• Oral PDE5 inhibitors (sildenafil, etc.)
• Pelvic/perineal trauma
• Prostate or bladder cancer
• Renal failure and dialysis
GENERAL PREVENTION
Oral pseudoephedrine (60 mg) if high-risk for recurrence has been suggested
DIAGNOSIS
HISTORY
• Pain, duration of priapism, precipitating factors, and prior episodes
• Medical, drug, and social history. Include intracorporal injection of PDE5 inhibitors
• Determine current level of sexual function
• Prior episodes; successful treatments
• History of perineal straddle injury, malignancy
PHYSICAL EXAM
• Palpation of penis will demonstrate nontender tumescence (nonischemic priapism) or tender rigidity (ischemic priapism).
• The hallmark of a priapism is that the corpora are involved but the glans penis and corpora spongiosum are flaccid and soft
• Abdominal, perineal, and digital rectal exam to search for traumatic or malignant etiology
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• CBC with differential and platelet count
– Reticulocyte count (may be increased in sickle cell disease)
• Sickle cell prep for “S” hemoglobin
• Hemoglobin electrophoresis
• Urine toxicology for prohibited drugs
• Psychoactive drug screen
• “Penile blood gas” (see below)
Imaging
• Color Doppler US imaging of the cavernous arteries can distinguish ischemic priapism (minimal arterial flow) from nonischemic priapism (high peak systolic arterial flow velocity)
– Color Doppler imaging may reveal cavernous arterial fistula or perineal arterial extravasation
• Pudendal arteriography (with the potential for therapeutic super-selective embolization) if nonischemic priapism is suspected
Diagnostic Procedures/Surgery
• Aspiration of cavernosal blood with a “butterfly needle” and blood gas syringe for “penile blood gas” allows differentiation between ischemic priapism (low pH, low PO2, high PCO2, blood is very dark) vs. nonischemic priapism (normal penile blood gas, blood bright red). Typical values:
– Ischemic priapism (pO2 <30 mm Hg, pCO2 >60 mm Hg, pH <7.25)
– Nonischemic priapism (pO2 >90 mm Hg, pCO2 <40 mm Hg, pH >7.4)
Pathologic Findings
Initially liquefactive necrosis of the corporal tissue; later corporal smooth muscle fibrosis
DIFFERENTIAL DIAGNOSIS
• Ischemic vs. nonischemic priapism
• “Pseudo priapism” in men with penile prosthesis, vacuum constriction device with band, intraurethral foreign body causing penile rigidity
TREATMENT
GENERAL MEASURES
• Appropriate differentiation between ischemic and nonischemic priapism is critical (1)
• Ischemic priapism of longer than 4-hr duration is a urologic emergency that requires prompt penile decompression. This is usually a bedside corporal aspiration with or without irrigation
• Aspirate cavernosal blood for “penile blood gas”
– Duplex color ultrasound has been suggested in lieu of penile blood gas to differentiate ischemic and nonischemic priapism
• All patients should undergo monitoring of blood pressure and pulse, peripheral IV placement, appropriate use of pain medication and sedation
MEDICATION
First Line (3)
• Ischemic priapism
– Use local anesthesia (lidocaine without epinephrine) and choose technique (local injection site, dorsal nerve block, etc.)
– Corporal body aspiration +/− irrigation with dilute adrenergic agent
Phenylephrine 100–500 mcg/mL (1 mL/1 mg) in 9 mL of injectable normal saline
A 27–29G needle is used to inject about 0.5 mL directly into the corpora every 3–5 min until a response. Can be repeated to a max of 1.5 mg phenylephrine has been administered or a total of 1 hr (if no response after 1 hr should be considered initial treatment failure)
Use lower volumes in children or with significant cardio vascular disease
Corporal compression helps facilitate the process
– This technique has best results for priapism <24 hr in duration:
Aspirate with a large needle (16–18G) connected to a 50-mL syringe and a 3-way stopcock. Insert the needle perpendicular into the skin into the lateral aspect of the corpora and aspirate 20–30 mL at a time (the glans is a less desirable site). Continue until the dark ischemic blood turns bright red
If not successful, aspirate and irrigate the corpora with dilute solution of phenylephrine (10 mg in 500 mL saline) using 10–20 mL each time
When aspirations and irrigations are completed, apply pressure for 5–10 min to limit hematoma and refilling of corpora
• Ischemic priapism in sickle cell disease:
– Opioid, analgesics, aggressive hydration, and supplemental oxygen if <4 hr duration
– Standard treatment if >4 hr, as for ischemic priapism above
– Terbutaline or other oral agents not recommended per AUA guidelines
• Nonischemic priapism
– No role for pharmacologic therapy
• Stuttering priapism
– Treat as for ischemic priapism
– LHRH agonists/antiandrogens may be considered (but not for children/adolescents)
– Intracavernous self-injection who fail or reject systemic treatment
Second Line
Injection of epinephrine (1 mg in 1,000 mL saline) has been used in place of phenylephrine; however, phenylephrine is more of a pure α-agonist with a lower systemic side-effect profile
SURGERY/OTHER PROCEDURES
• Surgical intervention is considered 2nd line after corporal injection/aspiration attempts fail
• Ischemic priapism
– If aspiration/irrigation fails, cavernosal glanular shunting is recommended; creating a fistula between the corpora cavernosa and the glans. Unilateral usually sufficient; if not successful perform bilateral procedure
– Distal cavernosal glanular shunt is 1st line
Winter shunt: 16G core biopsy needle passed from glans into 1 or both of the corporal bodies. Biopsy needle removes tissue core
Ebbehoj shunt using a pointed scalpel blade
Al-Ghorab shunt is an open excision of tunical tip and usually next if Winter shunt fails
T-shunt #11 scalpel blade inserted dorsolaterally to the meatus on both sides, and rotated (blade-edge) 90 degrees laterally
– Consider proximal shunting if distal shunting fails (cavernosal–spongiosal shunt [Quackles])
• Nonischemic priapism
– No role for shunting in nonischemic priapism
– Conservative measures are appropriate in the short term as nonischemic cases of priapism do not lead to underlying cavernosal tissue damage
– Duplex Doppler Ultrasonography with color flow to localize potential abnormal vascular accumulation (arteriovenous fistula, see image)
– Internal pudendal arteriography with selective embolization (clot or gel foam)
– Surgical exploration of the cavernosal body and ligation in cases refractory to embolization
ADDITIONAL TREATMENT
Radiation Therapy
N/A
Additional Therapies
Immediate placement of penile prosthesis if priapism is of significantly prolonged duration and ED is highly likely is advocated by some
Complementary & Alternative Therapies
N/A
ONGOING CARE
PROGNOSIS
• Based on duration/severity of ischemia. Priapism associated with sickle cell disease may resolve in 35% of patients treated systemically.
• Risk of permanent erectile dysfunction increases substantially after 24 hr of ischemic priapism (92% potency preserved with <1 day of priapism vs. 69% or less if more prolonged) (2).
• Monitoring of ischemic priapism may be clinical (complete flaccidity of the penis) or radiologic (color duplex Doppler ultrasonography showing persistent flow in cavernosal artery)
COMPLICATIONS
• Erectile dysfunction, particularly with cases of prolonged ischemic priapism
• Cavernosal urethral fistula (after cavernosal spongiosal shunt)
• Cavernositis and corporal fibrosis
• Penile deformity
FOLLOW-UP
Patient Monitoring
• Patient should be monitored for development of erectile dysfunction
• Patient should undergo appropriate testing to complete workup for any hematologic abnormalities or other potential underlying causes
Patient Resources
AUA Foundation. www.auanet.org/education/guidelines/priapism.cfm
REFERENCES
1. AUA Guidelines on the Management of Priapism – www.auanet.org/education/guidelines/priapism.cfm
2. Kulmala RV, Lehtonen TA, Tammela TL, et al. Preservation of potency after treatment after priapism. Scand J Urol Nephrol. 1996;30:313–316.
3. Salonia A, Eardley I2, Giuliano F3, et al. European Association of Urology guidelines on priapism. Eur Urol. 2014;65(2):480–489.
ADDITIONAL READING
N/A
See Also (Topic, Algorithm, Media)
• Priapism Algorithm 
• Sickle Cell Disease, Urologic Considerations
CODES
ICD9
607.3 Priapism
ICD10
• N48.30 Priapism, unspecified
• N48.33 Priapism, drug-induced
• N48.39 Other priapism
CLINICAL/SURGICAL PEARLS
• The hallmark of a priapism: Corpora are involved but the glans is flaccid and soft.
• Penile blood gas allows appropriate diagnosis.
• Ischemic priapism is an emergency and intervention should start within 4–6 hr, including decompression of the corpora cavernosa by aspiration and intracavernous injection of sympathomimetic drugs (eg, phenylephrine).
• Nonischemic priapism can be managed in a semielective manner once diagnosis confirmed.