Priapism: A Merck Manual of Patient Symptoms podcast

Priapism is painful, persistent, abnormal erection unaccompanied by sexual desire or excitation. It is most common in boys 5 to 10 yr and in men age 20 to 50 yr.

Pathophysiology

The penis is composed of 3 corporeal bodies: 2 corpora cavernosa and 1 corpus spongiosum. Erection is the result of smooth muscle relaxation and increased arterial flow into the corpora cavernosa, causing engorgement and rigidity.

Ischemic priapism: Most cases of priapism involve failure of detumescence and are most commonly due to failure of venous outflow (ie, low flow), also known as ischemic priapism. Severe pain from ischemia occurs after 4 h. If prolonged > 4 h, priapism can lead to corporeal fibrosis and subsequent erectile dysfunction or even penile necrosis and gangrene.

Stuttering priapism is a recurrent form of ischemic priapism with repeated episodes and intervening periods of detumescence.

Nonischemic priapism: Less commonly, priapism is due to unregulated arterial inflow (ie, high flow), usually as a result of formation of an arterial fistula after trauma. Nonischemic priapism is not painful and does not lead to necrosis. Subsequent erectile dysfunction is common.

Etiology

In adults, the most common cause (see Table 4: Symptoms of Genitourinary Disorders: Some Causes of Priapism) is

• Drug therapy for erectile dysfunction

In children, the most common causes are

• Hematologic disorders (eg, sickle cell disease, less commonly leukemia)

In many cases, priapism may be idiopathic and recurrent.

Table 4
PrintOpen table in new window
Some Causes of Priapism Cause Suggestive Findings Diagnostic Approach Drugs for erectile dysfunction: AlprostadilSome Trade Names CAVERJECT EDEX MUSE Click for Drug Monograph (injected, intraurethral) PapaverineSome Trade Names PAVABID Click for Drug Monograph (injected) PhentolamineSome Trade Names No US trade name Click for Drug Monograph (injected) Phosphodiesterase type 5 (PDE-5) inhibitors (sildenafilSome Trade Names VIAGRA Click for Drug Monograph , tadalafilSome Trade Names CIALIS Click for Drug Monograph , vardenafilSome Trade Names LEVITRA Click for Drug Monograph ) Painful ischemic priapism in men with history of treatment for erectile dysfunction Clinical evaluation Recreational drugs: Amphetamines Cocaine Painful ischemic priapism and psychomotor agitation and anxiety Clinical evaluation Sometimes toxicology screen Other drugs: β-Blockers (prazosinSome Trade Names MINIPRESS Click for Drug Monograph , tamsulosinSome Trade Names FLOMAX Click for Drug Monograph , terazosinSome Trade Names HYTRIN Click for Drug Monograph ) Anticoagulants (warfarinSome Trade Names COUMADIN Click for Drug Monograph ) Antihypertensives (nifedipineSome Trade Names ADALAT PROCARDIA Click for Drug Monograph ) Antipsychotics* (risperidoneSome Trade Names RISPERDAL Click for Drug Monograph , haloperidolSome Trade Names HALDOL Click for Drug Monograph , clozapineSome Trade Names CLOZARIL Click for Drug Monograph , quetiapineSome Trade Names SEROQUEL Click for Drug Monograph , trazodoneSome Trade Names DESYREL Click for Drug Monograph , chlorpromazineSome Trade Names THORAZINE Click for Drug Monograph ) Corticosteroids Hypoglycemics (tolbutamideSome Trade Names ORINASE Click for Drug Monograph ) LithiumSome Trade Names ESKALITH LITHOBID LITHONATE Click for Drug Monograph Methaqualone Painful ischemic priapism in men undergoing treatment for another medical disorder Clinical evaluation Hematologic disorders: Leukemia Lymphoma Sickle cell disease (rarely, sickle cell trait) Thalassemia Young males, often of African or Mediterranean descent CBC Hb electrophoresis Locally advanced prostate cancer Any metastatic disease Men > 50 with history of increasing symptoms of bladder outlet obstruction Prostate-specific antigen testing CT Spinal cord stenosis or compression Continuous epidural infusions Concomitant lower-extremity weakness CT or MRI of the spine Trauma (resulting in unregulated arterial inflow or arterial fistula formation) Nonischemic, nonpainful priapism in men with recent trauma Penile duplex ultrasonography Angiography MRI Rare causes: Cerebrospinal disorder (eg, syphilis, tumor) Genital infection and inflammation (eg, prostatitis, urethritis, cystitis), especially if complicated by a bladder calculus Pelvic hematoma or tumor Pelvic vein thrombosis Total parenteral nutrition Various Various *All atypical antipsychotics may cause priapism.

Evaluation

Priapism requires urgent treatment to prevent chronic complications (primarily erectile dysfunction). Evaluation and treatment should be done simultaneously.

History: History of present illness should cover the duration of erection, presence of partial or complete rigidity, presence or absence of pain, and any recent or past genital trauma. The drug history should be reviewed for offending drugs, and patients should be directly asked about the use of recreational drugs and drugs used to treat erectile dysfunction.

Review of systems should seek symptoms suggesting a cause, including dysuria (UTIs), urinary hesitancy or frequency (prostate cancer), fever and night sweats (leukemia), and lower-extremity weakness (spinal cord pathology).

Past medical history should identify known conditions associated with priapism (see Table 4: Symptoms of Genitourinary Disorders: Some Causes of Priapism), particularly hematologic disorders. Patients should be asked about a family history of hemoglobinopathies (sickle cell disease or thalassemia).

Physical examination: A focused genital examination should be done to evaluate extent of rigidity and tenderness and determine whether the glans and corpus spongiosum are also affected. Penile or perineal trauma and signs of infection, inflammation, or gangrenous change should be noted.

The general examination should note any psychomotor agitation, and the head and neck examination should look for pupillary dilation associated with stimulant use. The abdomen and suprapubic area should be palpated to detect any masses or splenomegaly, and a digital rectal examination should be done to detect prostatic enlargement or other pathology. Neurologic examination is useful to detect any signs of lower-extremity weakness or saddle paresthesias that might indicate spinal pathology.

Red flags: The following findings are of particular concern:

• Pain
• Priapism in a child
• Recent trauma
• Fever and night sweats

Interpretation of findings: In most cases, the clinical history reveals a history of drug treatment for erectile dysfunction, illicit drug use, or a history of sickle cell disease or trait; in these cases, no testing is indicated.

In patients with ischemic priapism, physical examination typically reveals complete rigidity with pain and tenderness of the corpus cavernosa and sparing of the glans and corpus spongiosum. By contrast, nonischemic priapism is painless and nontender, and the penis may be partially or completely rigid.

Testing: If the cause is not obvious, screening is done for hemoglobinopathies, leukemia, lymphoma, UTI, and other causes:

• CBC
• Urinalysis and culture
• Hb electrophoresis in blacks and men of Mediterranean descent

Many clinicians also do drug screening, intracavernosal ABG testing, and duplex ultrasonography. Penile duplex ultrasonography will show little or absent cavernosal blood flow in men with ischemic priapism and normal to high cavernosal blood flow in men with nonischemic priapism. Ultrasonography may also reveal anatomic abnormalities, such as cavernous arterial fistula or pseudoaneurysm, which usually indicate nonischemic priapism. Occasionally, MRI with contrast is useful to demonstrate arteriovenous fistulas or aneurysms.

Treatment

Treatment is often difficult and sometimes unsuccessful, even when the etiology is known. Whenever possible, patients should be referred to an emergency department; patients should preferably be seen and treated by a urologist. Other disorders should be treated. For example, priapism often resolves when sickle cell crisis is treated. Measures used to treat priapism itself depend on the type.

Ischemic priapism: Treatment should begin immediately, typically with aspiration of blood from the base of one of the corpora cavernosa using a nonheparinized syringe, often with saline irrigation and intracavernous injection of the α-receptor agonist phenylephrineSome Trade Names
NEO-SYNEPHRINE
Click for Drug Monograph
. For phenylephrineSome Trade Names
NEO-SYNEPHRINE
Click for Drug Monograph
injections, 1 mL of 1% phenylephrineSome Trade Names
NEO-SYNEPHRINE
Click for Drug Monograph
(10 mg/mL) is added to 19 mL of 0.9% saline to make 500 μg/mL; 100 to 500 μg (0.2 to 1 mL) is injected every 5 to 10 min until relief occurs or a total dose of 1000 μg is given. Before aspiration or injection, anesthesia is provided with a dorsal nerve block or local infiltration.

If these measures are unsuccessful or if priapism has lasted > 48 h (and is thus unlikely to resolve with these measures), a surgical shunt can be created between the corpus cavernosum and glans penis or corpus spongiosum and another vein.

Stuttering priapism: Stuttering priapism, when acute, is treated in the same way as other forms of ischemic priapism. There is a report of several cases caused by sickle cell disease that responded to a single oral dose of sildenafilSome Trade Names
VIAGRA
Click for Drug Monograph
. Treatments that may help prevent recurrences of stuttering priapism include antiandrogen therapy with gonadotropin-releasing hormone analogs, estrogen, bicalutamideSome Trade Names
CASODEX
Click for Drug Monograph
, flutamideSome Trade Names
EULEXIN
Click for Drug Monograph
, phosphodiesterase type-5 inhibitors, and ketoconazoleSome Trade Names
NIZORAL
Click for Drug Monograph
. The goal of antiandrogen therapy is to decrease the plasma testosterone level to < 10% of normal. DigoxinSome Trade Names
DIGITEK
LANOXIN
Click for Drug Monograph
, terbutalineSome Trade Names
BRETHINE
BRICANYL
Click for Drug Monograph
, gabapentinSome Trade Names
NEURONTIN
Click for Drug Monograph
, and hydroxyureaSome Trade Names
HYDREA
Click for Drug Monograph
have also been tried with some success.

Nonischemic priapism: Conservative therapy (eg, ice packs and analgesics) is usually successful; if not, selective embolization or surgery is indicated.

Refractory priapism: If other treatments are ineffective, a penile prosthesis can be placed.

Key Points

• Priapism requires urgent evaluation and treatment.
• Drugs (prescription and recreational) and sickle cell disease are the most common causes.
• Acute treatment is with α-agonists, needle decompression, or both.

Last full review/revision September 2009 by Seyed-Ali Sadjadi, MD

Content last modified February 2012