Priapism: Comprehensive Clinical Overview
Definition and Classification
Priapism is a persistent penile erection lasting >4 hours that is unrelated to sexual stimulation and requires emergency evaluation to prevent permanent erectile dysfunction. 1
There are two main types that require immediate differentiation:
- Ischemic (low-flow) priapism: Accounts for ~95% of cases, characterized by completely rigid, painful corpora cavernosa with little to no cavernous blood flow 1, 2
- Non-ischemic (high-flow) priapism: Accounts for ~5% of cases, presents with partial tumescence without full rigidity, typically painless, and is NOT a medical emergency 1, 3, 2
- Recurrent ischemic priapism (stuttering priapism): Repeated episodes of ischemic priapism with intervening periods of detumescence 1
Emergency Diagnostic Approach
Initial Evaluation
Every patient presenting with priapism must undergo immediate assessment including detailed history, physical examination, and corporal blood gas analysis. 1, 3
Critical History Elements 1:
- Duration of erection (time-dependent prognosis)
- Degree of pain (severe = ischemic; minimal/absent = non-ischemic)
- Previous priapism episodes and treatments
- Medications (especially intracavernosal injections, antipsychotics, trazodone)
- Perineal/genital trauma history
- Sickle cell disease or other hematologic disorders 1, 4
- Malignancies (particularly genitourinary or leukemia) 4, 5
Physical Examination Findings 1, 3:
- Ischemic: Completely rigid corpora cavernosa with severe tenderness; glans penis and corpus spongiosum remain soft 1, 6
- Non-ischemic: Partial corporal tumescence without full rigidity, non-tender 3, 7
Corporal Blood Gas Analysis
Obtain corporal blood gas immediately at presentation to definitively distinguish ischemic from non-ischemic priapism. 1, 3
Blood Gas Values 1, 3:
- Ischemic priapism: PO₂ <30 mmHg, PCO₂ >60 mmHg, pH <7.25
- Non-ischemic priapism: PO₂ >90 mmHg, PCO₂ <40 mmHg, pH 7.40
- Normal flaccid penis: Similar to mixed venous blood (PO₂ ~40 mmHg, PCO₂ ~50 mmHg, pH 7.35)
Blood gas may be omitted only in clear-cut cases: known intracavernosal injection-induced priapism, documented recurrent ischemic priapism in sickle cell patients, or when diagnosis is abundantly clear by history and examination alone. 1
Penile Duplex Doppler Ultrasound
Use penile duplex Doppler ultrasound only when the diagnosis remains indeterminate after history, examination, and blood gas analysis. 1, 3 Do not delay treatment in the emergency setting to obtain imaging when the clinical picture is clear. 6
Management of Acute Ischemic Priapism
Critical Time-Dependent Principle
Ischemic priapism is a compartment syndrome requiring immediate intervention—untreated episodes lead to irreversible corporal fibrosis and permanent erectile dysfunction. 1, 6
Prognosis by Duration 3, 6:
- <24 hours: Reasonable chance of erectile function preservation
- 24-36 hours: Significantly increased risk of erectile dysfunction
- >36 hours: High likelihood of permanent erectile dysfunction (0% return of spontaneous functional erections if untreated)
First-Line Treatment Algorithm
Immediately initiate intracavernosal phenylephrine with corporal aspiration as first-line treatment, regardless of underlying etiology. 3, 6
Step 1: Corporal Aspiration 3, 6:
- Insert 19 or 21 gauge needle into corpus cavernosum
- Aspirate dark, deoxygenated blood
- Resolution rate: 24-36% with aspiration alone
Step 2: Intracavernosal Phenylephrine 3, 6:
- Concentration: 100-500 mcg/mL
- Maximum dose: 1000 mcg within the first hour
- Success rate: 43-81% when combined with aspiration
- Repeat injections should be performed before considering surgery
Step 3: Surgical Shunt 1, 6:
- Consider only after repeated phenylephrine injections fail
- Various shunt techniques available (distal to proximal approaches)
Common Pitfalls to Avoid
Never delay intracavernous treatment to pursue systemic therapies alone, even in patients with sickle cell disease or leukemia—this guarantees erectile dysfunction. 3, 6
- Do not wait for laboratory results if clinical diagnosis is clear 6
- Do not proceed directly to surgery without attempting repeated phenylephrine injections 6
- Do not perform penile duplex Doppler in the emergency setting when diagnosis is clear 6, 7
Special Populations
Sickle Cell Disease
In sickle cell patients with acute ischemic priapism, urologic relief of the erection takes absolute priority—standard sickle cell interventions should occur concurrent with (not instead of) intracavernous treatment. 1, 3
- Exchange transfusion should NOT be used as primary treatment for acute ischemic priapism 3
- Systemic sickle cell therapy alone should never be the only treatment, as this is a compartment syndrome requiring direct intracavernous intervention 6
- Standard sickle cell assessment (hydration, oxygenation, analgesia) should be provided simultaneously with urologic intervention 1
Leukemia and Hematologic Disorders
Patients with leukemia presenting with priapism require the same immediate intracavernous treatment as other causes. 3, 4
- Hyperviscosity from leukemia is a rare cause of priapism 5
- Leukapheresis may be considered as an adjunctive measure to reduce viscosity, but should not delay intracavernous treatment 5
- Prophylaxis should be encouraged in high-risk hematologic patients 4
Management of Non-Ischemic Priapism
Non-ischemic priapism is NOT a medical emergency and does not require urgent urologic intervention. 1, 3, 7
Initial Management 3:
- Observation for up to 4 weeks is appropriate, as fistulas may close spontaneously
- Painless tumescent erection can be observed at home
If Priapism Persists 3:
- Perform penile duplex Doppler ultrasound to identify fistula location
- Percutaneous fistula embolization is first-line therapy if patient desires treatment
- Treatment decisions must be based on patient objectives, available resources, and clinician experience 1
Management of Recurrent Ischemic Priapism
Recurrent ischemic priapism requires both treatment of acute episodes and preventative strategies to avoid future ischemic events necessitating surgical management. 1
Acute Episode Management 1:
- Patients may be counseled to abort persistent erections using at-home phenylephrine injections before meeting the 4-hour criteria
- Clinician judgment overrides stricter definitions in recurrent cases
Preventative Strategies 3:
Optimal strategies to prevent subsequent episodes are unknown, but several options exist: 1
- PDE5 inhibitors: Tadalafil or sildenafil (daily dosing)
- Ketoconazole with prednisone: Hormonal regulation
- Hydroxyurea: Specifically for sickle cell disease patients
- Home self-injection of phenylephrine: On as-needed basis for early episodes
Critical Patient Counseling 3:
- Hormonal regulators (ketoconazole, cyproterone acetate) may impair fertility and sexual function
- Potential side effects include fatigue, hot flashes, breast tenderness, mood changes, and erectile dysfunction
- Evidence for preventative strategies is sparse and limited 1
Etiologies to Investigate
Order additional diagnostic testing to determine the underlying etiology of priapism. 1
Common Causes 1, 2, 8:
- Idiopathic: Most common in adults
- Medications: Intracavernosal injections (papaverine, phentolamine), antipsychotics, trazodone, total parenteral nutrition
- Hematologic disorders: Sickle cell disease (most common in children), leukemia, glucose-6-phosphate dehydrogenase deficiency 4, 9
- Trauma: Blunt perineal/straddle injury (typically causes non-ischemic type)
- Neoplasia: Genitourinary malignancies, metastatic disease
Pediatric Considerations
Priapism in children is most commonly associated with sickle cell disease and requires the same urgent intracavernous treatment as adults, with dose adjustments and adequate sedoanalgesia. 9
- Treatment demands appropriate drug dose adjustments for pediatric patients 9
- Adequate sedoanalgesia must cover procedures involving pain or trauma 9
- May cause serious sequelae including impotence, erectile dysfunction, or psychogenic sexual aversion affecting future sexual life 9
Long-Term Sequelae
Impotence is a common sequela of priapism, particularly when treatment is delayed. 8