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 Overview of Urinary Tract Symptoms Kidney and urinary tract disorders can involve one or both kidneys, one or both ureters, the bladder, or the urethra, and in men, the prostate, one or both testes, or the epididymis. Problems... read more .)
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 Erectile Dysfunction (ED) Erectile dysfunction (ED) is the inability to attain or sustain an erection satisfactory for sexual intercourse. (See also Overview of Sexual Dysfunction in Men.) Every man occasionally has... read more 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
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
Blood disorders (for example, sickle cell disease Sickle Cell Disease Sickle cell disease is an inherited genetic abnormality of hemoglobin (the oxygen-carrying protein found in red blood cells) characterized by sickle (crescent)-shaped red blood cells and chronic... read more
and, less commonly, leukemia Overview of Leukemia Leukemias are cancers of white blood cells or of cells that develop into white blood cells. White blood cells develop from stem cells in the bone marrow. Sometimes the development goes awry... read more )
Less common causes
Less common causes include
Use of drugs (other than those used to treat erectile dysfunction), such as certain antidepressants (for example, trazodone) or antihypertensive drugs, anticoagulants, corticosteroids, lithium, antipsychotic drugs, cocaine, and amphetamines
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
In boys and men with priapism, certain symptoms and characteristics are cause for concern. They include
Severe pain
Age less than 10 years
Recent injury to the penis or groin area
Fever and night sweats
When to see a doctor
All boys and men who have priapism should see a doctor immediately for treatment. If warning signs are present, further evaluation may be necessary to determine whether the cause of priapism is something unusual or serious.
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 Some Causes and Features of Priapism 
).
Doctors ask
How long the erection has been present
Whether there is pain
Whether there has been an injury to the penis or the groin area
Whether conditions (such as sickle cell disease Sickle Cell Disease Sickle cell disease is an inherited genetic abnormality of hemoglobin (the oxygen-carrying protein found in red blood cells) characterized by sickle (crescent)-shaped red blood cells and chronic... read more
) that may cause priapism are presentWhat 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.
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 Erectile Dysfunction (ED) Erectile dysfunction (ED) is the inability to attain or sustain an erection satisfactory for sexual intercourse. (See also Overview of Sexual Dysfunction in Men.) Every man occasionally has... read more . 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 Overview of Urinary Tract Infections (UTIs) In healthy people, urine in the bladder is sterile—no bacteria or other infectious organisms are present. The tube that carries urine from the bladder out of the body (urethra) contains no bacteria... read more . Testing includes
A complete blood count
Urinalysis Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more
and urine culture Urinalysis and Urine Culture Urinalysis, the testing of urine, may be necessary in the evaluation of kidney and urinary tract disorders and can also help evaluate bodywide disorders such as diabetes or liver problems. A... read more Sometimes hemoglobin electrophoresis, particularly in boys and men of African or Mediterranean descent
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 Magnetic resonance imaging There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more (MRI) or computed tomography Computed tomography There are a variety of tests that can be used in the evaluation of a suspected kidney or urinary tract disorder. (See also Overview of the Urinary Tract.) X-rays are usually not helpful in evaluating... read more (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.
Key Points
Priapism is an emergency that requires urgent evaluation and treatment.
Drugs, including those used to treat erectile dysfunction, and sickle cell disease are the most common causes.
Treatment usually involves injecting a drug into the penis and removing the excess blood from it.
