Persistent erection (priapism) is a painful, persistent, abnormal erection unaccompanied by sexual desire or excitation. It is most common in boys aged 5 to 10 years and in men aged 20 to 50 years. (See also Overview of Urinary Tract Symptoms.)
The penis is composed of three cylindrical spaces (sinuses) of tissue through which blood can flow (called erectile tissue). The larger two sinuses, the corpora cavernosa, occur side by side. The third sinus (the corpus spongiosum) surrounds the urethra and ends as the cone-shaped end of the penis (glans penis). When these sinuses fill with blood, the penis becomes larger and rigid (erect). Muscles then tighten around the veins of the groin, preventing blood from flowing out of the penis and keeping the penis erect.
Ischemic priapism
Most cases of persistent erection involve failure of blood to flow out of the penis. Blood backs up, preventing new oxygen-rich blood from entering the penis. As a result, the penis can become starved of oxygen. This condition is known as ischemic priapism or low-flow priapism. Severe pain occurs if an erection lasts longer than 4 hours. The penis may be erect while the glans penis may be soft. Prolonged priapism can lead to erectile dysfunction or even the death of penile tissue.
Stuttering priapism is a recurring form of ischemic priapism in which episodes of erection alternate with periods when the penis is not erect.
Nonischemic priapism
Less commonly, priapism is due to uncontrolled flow of blood into the penis. Such abnormal blood flow usually results from an injury to an artery in the groin area. Nonischemic priapism is also known as high-flow priapism. It is less painful than ischemic priapism and does not lead to tissue death. The penis is erect but not fully rigid. Subsequent erectile dysfunction is much less common than in ischemic priapism.
Causes of a Persistent Erection
Priapism probably results from abnormalities of blood vessels, red blood cells, or nerves that cause blood to become trapped in the erectile tissue of the penis. Sometimes doctors are not able to determine the cause of priapism.
Common causes
Causes differ somewhat based on age.
In men, the most common cause is
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Drugs taken to treat erectile dysfunction
Drugs taken to cause an erection, including those taken by mouth (avanafil, sildenafil, tadalafil, and vardenafil) and those injected into the penis (for example, alprostadil), can cause priapism.
In boys, the most common causes are
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Blood disorders (for example, sickle cell disease and, less commonly, leukemia)
Less common causes
Evaluation of a Persistent Erection
The following information can help people know when to see a doctor and what to expect during the evaluation.
Warning signs
When to see a doctor
What the doctor does
Doctors first ask questions about symptoms and medical history and then do a physical examination. What they find during the history and physical examination often suggests a cause of priapism and the tests that may need to be done (see table Some Causes and Features of Priapism).
Doctors ask
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How long the erection has been present
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Whether there is pain
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Whether there has been an injury to the penis or the groin area
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Whether conditions (such as sickle cell disease) that may cause priapism are present
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What drugs have been taken, including drugs for erectile dysfunction and recreational drugs
Although doctors focus the physical examination on the genitals to detect signs of injury or cancer, they also examine the abdomen and do a digital rectal examination. Doctors may also do a neurologic examination to look for signs of a spinal cord disorder.
Some Causes and Features of Priapism
|
Cause |
Common Features* |
Tests |
|
Drugs for erectile dysfunction (such as alprostadil, papaverine, phentolamine, avanafil, sildenafil, tadalafil, or vardenafil) |
Painful priapism in men who took one of these drugs immediately before priapism started |
Only a doctor's examination |
|
Recreational drugs (such as amphetamines and cocaine) |
Painful priapism If amphetamines or cocaine is the cause, agitation and anxiety |
A doctor's examination Occasionally drug screening |
|
Other drugs (such as anticoagulants, certain antidepressants, antihypertensive drugs, psychostimulants, antipsychotic drugs, corticosteroids, or lithium) |
Painful priapism in boys or men being treated for a disorder |
Only a doctor's examination |
|
Blood disorders (such as leukemia, multiple myeloma, sickle cell disease or trait, or thalassemia) |
In boys or young men, often of African or Mediterranean descent |
A complete blood count Blood tests to check for abnormal hemoglobin (hemoglobin electrophoresis) |
|
Prostate cancer that has spread to areas next to the prostate or any cancer that has spread to the genitals |
In men over 50 who have worsening symptoms indicating that the opening from the bladder into the urethra (bladder outlet) is blocked (such as a weak urine stream, difficulty starting urination, and dribbling at the end of urination) Sometimes blood in the urine |
Blood tests to measure the level of prostate-specific antigen CT or MRI |
|
Spinal cord disorders, such as narrowing of the spinal canal (spinal cord stenosis) or compression of the spinal cord |
Weakness or numbness in the legs Retention of urine or uncontrollable loss of urine or stool (urinary or fecal incontinence) |
MRI or CT of the spine |
|
Injury to an artery |
Mildly painful and slightly rigid priapism In men who have had a recent injury to the penis or groin area |
Duplex ultrasonography of the penis (ultrasonography that measures blood flow and shows structure of the blood vessels through which the blood is flowing) Angiography (x-rays of blood vessels) MRI |
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* Features include symptoms and the results of the doctor's examination. Features mentioned are typical but not always present. |
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CT = computed tomography; MRI = magnetic resonance imaging. |
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Testing
The need for testing depends on what doctors find during the history and physical examination. Often, the type of priapism (ischemic or nonischemic) and cause are obvious, such as the use of a drug to treat erectile dysfunction. If it is not clear whether priapism is ischemic or nonischemic, doctors may take a sample of blood from the penis to test for the presence of oxygen and other gases (arterial blood gas measurement). They may also do duplex ultrasonography (ultrasonography that measures blood flow and shows structure of the blood vessels through which the blood is flowing). These tests help differentiate ischemic from nonischemic priapism. Ultrasonography may also show the blood flow patterns in priapism and the anatomic abnormalities contributing to priapism. If the cause is still not obvious, doctors test for blood disorders and urinary tract infections. Testing includes
Hemoglobin electrophoresis is a blood test to check for abnormal hemoglobin (the protein that carries oxygen in red blood cells) as occurs in sickle cell disease.
Because some boys and men may be embarrassed to admit they have used recreational drugs, doctors sometimes do drug screening. Occasionally, magnetic resonance imaging (MRI) or computed tomography (CT) is also done.
Treatment of a Persistent Erection
Simple measures that can be taken immediately include applying ice, climbing stairs, or both. However, priapism is an emergency. Treatment should begin as soon as possible, preferably by a urologist in an emergency department.
Doctors give boys and men who have significant pain a pain killer (analgesic). Other measures are usually needed if priapism is ischemic. After numbing the penis with a local anesthetic, doctors may inject the penis with a drug that causes the blood vessels carrying blood to the penis to narrow (for example, phenylephrine), decreasing blood flow to the penis and causing the swelling to subside. Doctors may also draw blood out of the penis using a needle and syringe (aspiration). Drawing out blood helps reduce pressure and swelling. Sometimes doctors also flush the veins of the penis with a salt water (saline) solution to help remove oxygen-depleted blood or blood clots.
These measures may be repeated. If they are still not effective, doctors may create a surgical shunt. A shunt is a passageway that is surgically inserted into the penis to divert excess blood flow and allow circulation in the penis to return to normal.
