What are the types and treatment options for priapism?

Priapism: Comprehensive Overview

Anatomy and Physiology

The penis contains three erectile bodies: two corpora cavernosa (which become rigid during priapism) and the corpus spongiosum (which typically remains soft). 1 Normal erection involves arterial inflow and venous outflow regulation through smooth muscle relaxation and contraction in the corpora cavernosa. 1

• The corpora cavernosa are paired cylindrical structures that run along the dorsal aspect of the penis and are responsible for penile rigidity during erection 1
• The corpus spongiosum surrounds the urethra and forms the glans penis, which typically remains flaccid during priapism episodes 1
• Normal detumescence requires sympathetic nervous system activation, causing smooth muscle contraction and venous drainage 1

Pathophysiology

Priapism results from failure of the normal detumescence mechanism, leading to prolonged erection unrelated to sexual stimulation. 1

Ischemic (Low-Flow) Priapism Pathophysiology:

• Venous outflow obstruction causes blood stagnation in the corpora cavernosa with hypoxia, hypercarbia, and acidosis (pO2 <30 mmHg, pCO2 >60 mmHg, pH <7.25) 2, 3
• Progressive ischemia leads to smooth muscle necrosis, fibrosis, and permanent erectile dysfunction if untreated 1
• The risk of permanent damage increases dramatically after 24 hours and approaches 90% after 48 hours 2, 3

Non-Ischemic (High-Flow) Priapism Pathophysiology:

• Unregulated arterial inflow, typically from traumatic arterio-cavernosal fistula formation, causes persistent but non-ischemic erection 1
• Blood gases remain normal (not hypoxic or acidotic) because arterial blood continues to flow through the corpora 1
• No time-dependent tissue damage occurs, making this a non-emergent condition 1

Types of Priapism

Priapism is classified into three distinct subtypes based on pathophysiology, each requiring completely different management approaches. 1

1. Ischemic (Veno-Occlusive, Low-Flow) Priapism:

• This is a urologic emergency requiring immediate intervention 1, 2
• Characterized by rigid, painful corpora cavernosa with little to no cavernous blood flow 1
• Blood gas analysis shows hypoxia (pO2 <30 mmHg), hypercarbia (pCO2 >60 mmHg), and acidosis (pH <7.25) 2, 3
• Patients report severe pain and the penis is completely rigid except for the glans 3
• Represents approximately 95% of all priapism cases 4
• Common etiologies include idiopathic causes, sickle cell disease, medications (antipsychotics, antidepressants, erectile dysfunction drugs), and malignancy 1

2. Non-Ischemic (Arterial, High-Flow) Priapism:

• This is NOT an emergency and does not require urgent intervention 1, 5
• Characterized by semi-rigid, painless erection with normal arterial inflow 1
• Blood gases are normal (not hypoxic or acidotic) 1
• Most commonly caused by blunt perineal or penile trauma creating an arterio-cavernosal fistula 1, 5
• Color Doppler ultrasound shows high cavernosal arterial flow 2, 3
• Many cases resolve spontaneously without intervention 1, 6

3. Stuttering (Recurrent, Intermittent) Priapism:

• This is a recurrent form of ischemic priapism with repeated self-limited episodes separated by periods of detumescence 1
• Each acute episode is ischemic in nature and requires emergency treatment 1
• Commonly occurs in patients with sickle cell disease 1, 7
• Management focuses on both treating acute episodes AND preventing future occurrences 1, 6
• Patients may be taught self-administration of intracavernosal phenylephrine for early episodes not yet meeting 4-hour criteria 3

Diagnosis

All patients presenting with prolonged erection must be evaluated emergently to differentiate between ischemic and non-ischemic subtypes, as management differs completely. 2, 3

Essential History Elements:

• Duration of erection (priapism defined as >4 hours) 1
• Degree of pain (severe pain suggests ischemic; minimal pain suggests non-ischemic) 1
• History of trauma (suggests non-ischemic) 1, 5
• Medication use (erectile dysfunction drugs, antipsychotics, antidepressants, anticoagulants) 1
• Previous priapism episodes and their treatment 1
• Sickle cell disease or other hematologic disorders 1
• Baseline erectile function 1

Physical Examination:

• Ischemic priapism: completely rigid corpora cavernosa with spared soft glans and corpus spongiosum 3
• Non-ischemic priapism: semi-rigid penis that is not fully erect and not painful 1
• Examine genitalia and perineum for signs of trauma 1

Diagnostic Testing:

Cavernosal blood gas analysis is the gold standard for differentiating priapism types and should be obtained at initial presentation. 1, 2

• Ischemic priapism blood gas: pO2 <30 mmHg, pCO2 >60 mmHg, pH <7.25 2, 3
• Non-ischemic priapism blood gas: normal arterial values (pO2 >90 mmHg, pCO2 <40 mmHg, pH >7.35) 2
• Color Doppler ultrasound may be used when diagnosis is indeterminate, showing minimal to absent cavernosal arterial flow in ischemic priapism and high flow in non-ischemic priapism 1, 2
• Additional laboratory testing to determine etiology (complete blood count, hemoglobin electrophoresis if sickle cell suspected, toxicology screen) 1

Treatment and Management

Ischemic Priapism Treatment (EMERGENCY):

Immediate urologic emergency treatment with corporal aspiration and intracavernosal phenylephrine injection is required for ischemic priapism, regardless of underlying causes. 3

First-Line Treatment:

• Intracavernosal phenylephrine injection combined with aspiration has a 43-81% success rate 2, 3
• Phenylephrine is superior to other sympathomimetics due to demonstrated efficacy and limited systemic side effects 2
• Standard concentration: 100-500 mcg/mL phenylephrine 2
• Maximum dose: 1000 mcg within the first hour 2, 3
• Technique: Aspirate blood from corpora cavernosa using large-bore needle (16-19 gauge), then inject phenylephrine 1
• Repeat injections should be performed prior to considering surgical intervention 3
• Aspiration/irrigation alone has only 24-36% success rate 2

Second-Line Treatment (If Medical Management Fails):

Surgical shunting is indicated when repeated intracavernosal phenylephrine injections fail. 2, 3

• Start with distal shunts (Winter, Ebbehoj, T-shunt) which have 60-80% success rates 2, 3
• Distal shunts create communication between corpora cavernosa and corpus spongiosum or glans 1
• Proximal shunts (Quackels, Grayhack) are reserved for distal shunt failures but carry higher erectile dysfunction risk 2, 3
• Proximal shunts create communication between corpora cavernosa and saphenous or dorsal penile veins 1

Third-Line Treatment:

• Early penile prosthesis implantation should be considered for long-lasting priapism (>36-48 hours) or failed shunting procedures 1, 5
• Immediate prosthesis placement may preserve penile length and prevent severe fibrosis 1

Non-Ischemic Priapism Treatment (NON-EMERGENCY):

Non-ischemic priapism does not require urgent urologic intervention and many cases resolve spontaneously. 1, 5

• Initial management is conservative observation, as most episodes are self-limiting 1, 6, 5
• Ice packs and compression may be attempted 6
• If intervention is desired, selective arterial embolization is the treatment of choice with high success rates 1, 5
• Embolization targets the arterio-cavernosal fistula using absorbable materials to preserve future erectile function 5
• Intracavernosal phenylephrine and surgical shunting are NOT appropriate for non-ischemic priapism 1

Stuttering (Recurrent) Priapism Management:

Management requires both treatment of acute ischemic episodes AND prevention of future occurrences. 1, 6

Acute Episode Treatment:

• Treat each acute episode according to ischemic priapism protocols (aspiration and phenylephrine) 1, 6
• Patients may be taught self-administration of intracavernosal phenylephrine at home for episodes not yet meeting 4-hour criteria 3
• Patient education should cover injection site, dosing, systemic side effects, and duration of erection before self-injection 3

Prevention Strategies:

• Implement preventive pharmacotherapy to reduce future priapism episodes, considering PDE5 inhibitors 2, 3
• Hormonal therapy (GnRH agonists, anti-androgens) may reduce recurrence frequency 2
• Oral sympathomimetics (pseudoephedrine, terbutaline) taken at onset of erection may abort early episodes 6
• Treat underlying conditions (sickle cell disease with hydroxyurea, exchange transfusion) 1

Special Population: Sickle Cell Disease

Patients with sickle cell disease presenting with ischemic priapism should receive immediate urologic intracavernosal treatment, with concurrent systemic sickle cell interventions. 2, 3

• Systemic sickle cell treatments alone (hydration, oxygenation, exchange transfusion) resolved priapism in only 0-37% of patients 2
• Do not delay urologic intervention while waiting for systemic treatments to work 2
• Concurrent management includes hydration, oxygenation, analgesia, and hematology consultation 1, 2
• Hydroxyurea may prevent future episodes in patients with recurrent priapism 1

Critical Timing and Outcomes

The risk of permanent erectile dysfunction increases significantly after 24 hours of ischemia and approaches 90% after 48 hours, emphasizing the absolute necessity for prompt treatment. 2, 3

• Intervention should ideally begin within 4-6 hours of onset 5
• Early intervention with intracavernosal phenylephrine and aspiration can reduce the risk of erectile dysfunction 2
• Delayed treatment results in cavernosal smooth muscle necrosis, fibrosis, and permanent erectile dysfunction 1
• Even with successful detumescence, persistent penile edema, ecchymosis, and partial erections may occur and can mimic unresolved priapism 1
• Resolution can be verified by measurement of cavernous blood gases or blood flow measurement by color duplex ultrasonography 1

Common Pitfalls and Caveats

• Never delay treatment of ischemic priapism for diagnostic workup beyond blood gas analysis 1
• Do not use intracavernosal phenylephrine or surgical shunting for non-ischemic priapism 1
• Do not confuse post-treatment penile edema with persistent priapism; verify resolution with blood gas or ultrasound 1
• Monitor blood pressure and cardiac status during phenylephrine administration, especially in patients with cardiovascular disease 2
• In sickle cell patients, do not rely solely on systemic treatments; immediate urologic intervention is required 2, 3
• Testosterone therapy may contribute to priapism risk, but do not discontinue acutely during the emergency; address after resolution 3