Priapism

Priapism is a persistent (longer than 4 hours) erection that is not caused by sexual desire or sexual stimulation, or relieved by ejaculation.

Priapism is caused by problems with the nerves or blood vessels in the penis, which results in blood remaining trapped in the penis’ erectile tissue – the corpora cavernosa. It is a fairly uncommon condition, affecting around 1 in 200,000 males annually in Australia.

Priapism can be serious and can result in a loss of sexual function unless treatment is sought as soon as possible (within 24 hours). If your erection lasts for longer than 4 hours, you should see a doctor immediately to avoid permanently damaging your penis.

Types of priapism

There are 3 types of priapism, which are caused by different mechanisms.

Low blood flow priapism

Also known as ischaemic priapism, this is easily the most common type of priapism. It is also the most dangerous as it can cause permanent damage to the penis if not treated promptly. It results from blood becoming trapped in the penile tissue due to blockage of a blood vessel, or because penile muscles aren’t contracting normally to ‘squeeze’ the blood out of the penis.

A blocked blood vessel also means that fresh blood is unable to reach the penile tissue with oxygen and other nutrients essential for tissue survival. This can cause permanent damage to your penis as the tissue affected by the blockage dies, eventually affecting your ability to get an erection. This is why it is essential to seek medical attention if you experience an erection that lasts longer than 4 hours.

Because of penile tissue damage and the pressure exerted by the trapped blood, low blood flow priapism is often painful and the penis remains very rigid.

High-blood flow priapism

High blood flow priapism is quite rare and usually results from injury to the genitals or surrounding areas. The usual cause is rupture of one of the blood vessels servicing the penis causing blood to flow uncontrollably into the penile tissue. If you have this type of priapism, your prolonged erection may not be as rigid as it would be when you are sexually aroused and it usually isn’t painful.

‘Stuttering’ priapism

This type of priapism is similar to low-blood flow priapism except that it is episodic. The re-occurring, painful erections usually last between 2 and 3 hours before returning to a flaccid (soft or limp) state. If you have this type of priapism, it may occur during sleep, or before or after sexual stimulation. Over time, the episodes of priapism may become more frequent and last longer. Like low blood flow priapism, this type of priapism can cause permanent damage to the penis and affect your sexual function. It is important to seek medical treatment if this is happening to you.

Causes of priapism

Medicines

Low-blood flow priapism is a possible side effect of certain prescription medications, and of illicit drugs such as marijuana, ecstasy, cocaine and methamphetamine (crystal meth). Prescription medicines that can result in low-blood flow priapism include:

  • the blood-thinning drugs (anticoagulants), heparin and warfarin
  • methylphenidate (Ritalin, Concerta), a medicine used to manage attention deficit hyperactivity disorder
  • some drugs used to treat people with mental illnesses like schizophrenia and depression
  • many types of high-blood pressure medicines
  • injections that are used to treat impotence, such as alprostadil and papaverine (a common cause of priapism in Australia)
  • some hormones such as gonadotropin-releasing hormone, tamoxifen and testosterone.

Sickle cell disease and other blood diseases

Sickle cell disease covers a number of life-threatening, inherited conditions where the body produces abnormally shaped red blood cells that have a tendency to become stuck in blood vessels. Sickle cell disease is not a common cause of priapism in Australia as it is a rare disease in the Australian population, however, elsewhere it is the leading cause of priapism in boys and a significant cause in adult men.

Other blood disorders that are less frequently associated with priapism include blood cancers (leukaemia and multiple myeloma), blood clots, and a rare disease similar to sickle cell disease called thalassemia.

Other causes

Other causes of priapism include:

  • conditions that affect the nervous system and so indirectly affect blood flow to the penis, such as brain or spinal cord tumours or injury.
  • tumours of the prostate, bladder or kidney, which can upset blood flow to the penis
  • Infections in the genitals, such as prostatitis or urethritis.

Diagnosing priapism

Your doctor will need to determine which type of priapism you have as this impacts your treatment. It is also important to try to establish if there is an underlying cause of your priapism, such as the medicines you are taking. To do this they will need to ask you questions about your priapism and take a medical history, as well as perform a physical examination.

The next step will be to order a number of blood tests to rule out a blood disorder or infection as the cause of your priapism.

In addition, your doctor may recommend one of the following tests.

  • Blood–gas analysis of blood taken from your penile tissue – this helps determine whether your priapism is low or high-blood flow priapism.
  • Colour duplex ultrasonography – this is an alternative test to blood–¬gas analysis that helps your doctor establish the type of priapism you have. It allows your doctor to visualise the blood flow in your penis and surrounding area.
  • Magnetic resonance imaging of your penis – although rarely used, this test enables your doctor to see if there is any damaged or dead tissue present in your penis. It also helps identify possible causes of priapism, such as a tumour or blood clot.
  • Other blood and urine tests may sometimes be requested to rule out recreational drugs as the cause of your priapism.

Treating low blood flow and stuttering priapism

Initial treatment you can try at home

In some cases, ice packs to the penis and perineum (the area between the base of the penis and the anus), or vigorous exercise such as climbing stairs, may help end the erection. However, it is still important to see a doctor for treatment to avoid permanent damage to your penis.

Initial treatment in hospital

For immediate relief and to restore normal blood flow to prevent permanent damage, the doctor may use a needle under local anaesthetic to drain the trapped blood from your penis. They may also inject a vasoconstrictor agent (a medicine used to narrow blood vessels). If this approach doesn’t work, you may need to have urgent surgery.

Further treatment

In general, the type of treatment or medicine recommended for priapism depends on its cause.

  • If a medicine is the suspected cause of priapism, your doctor may suggest that you stop taking that medicine and try an alternative.
  • If you have a blood clot in the penis, you will need to have surgery to remove it so that blood can flow normally through the penis again.
  • If you have sickle cell disease, specific treatments may be recommended. These measures would be in addition to draining the extra blood trapped in the penis and injecting a vasoconstrictor agent.
  • If you have stuttering priapism, you may be given medicines to prevent further episodes. This could be short-term self-injection with a medicine called phenylephrine to control blood flow to the penis when priapism occurs. Another option is a course of hormone treatment that helps reduce your testosterone levels. This therapy is only recommended for adults.
  • If you develop significant impotence as a result of your priapism, you may need a penile prosthesis implant.

Treatment of high blood flow priapism

If you have high blood flow priapism the initial treatment is to wait and see. Priapism tends to resolve of its own accord in about two-thirds of men with this condition. If your priapism does not resolve, you may need surgery to block off the offending blood vessels to reduce the blood flow into your penis.

Last Reviewed: 23 June 2016
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References

1. Al-Qudah et al for Medscape. Priapism (updated Oct 2015) http://emedicine.medscape.com/article/437237-overview (accessed Jun 2016).
2. Huang YC et al. Evaluation and management of priapism: 2009 update. Nat Rev Urol 2009; 6: 62–71.
3. Levey HR et al. Management of priapism: an update for clinicians. Ther Adv Urol 2014; 6: 230–44.
4. Montague DK et al for American Urological Association. Guideline on the management of priapism, 2003.
5. NHS Choices. Priapism (updated Feb 2015) http://www.nhs.uk/Conditions/Priapism/Pages/Introduction.aspx (accessed Jun 2016).
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