Priapism is a persistent and often painful erection that lasts for several hours.
The erection is not necessarily related to sexual stimulation or excitement, and does not subside after ejaculation (when semen is released from the penis).
The erection lasts longer than four hours. During this time, the shaft of the penis is rigid and inflexible, but the head of the penis (the glans) is usually soft. The penis is also painful or tender.
Priapism is a medical emergency – you should seek immediate medical assistance if you think you have it.
If it's not treated within 24 hours, your penis may be permanently damaged and you may have difficulties getting an erection in the future.
Types of priapism
There are two main types of priapism:
- low blood flow (ischaemic) priapism – the most common and serious type of priapism usually caused by a blockage in the arteries of the penis
- high blood flow (non-ischaemic) priapism – much rarer and usually caused by an injury to the genitals or perineum (the area in between the genitals and anus)
What causes priapism?
Priapism happens when blood that fills the spongy tissue of the penis during an erection is unable to flow out of the penis. This can be caused by:
- a complication of sickle cell anaemia (a genetic blood disorder where the red blood cells develop abnormally)
- a side effect of medications, such as sildenafil, used to treat erectile dysfunction
If you have ischaemic (low blood flow) priapism, the sooner you receive treatment, the more effective it is likely to be.
Aspiration, a procedure that uses a needle and syringe to drain the blood out of your penis, is usually recommended.
If this does not work, medication may be injected into your penis which squeezes the blood vessels and helps push the blood out of your penis.
Surgery is only recommended if other treatments have failed. There are a number of different surgical procedures available, depending on the type of priapism you have.
Read more about how priapism is treated.
Priapism is caused by a problem with the blood supply to the penis. Certain medical conditions and medications can prevent blood leaving the penis.
When a man becomes sexually aroused, his nervous system releases a chemical called nitric oxide. Nitric oxide relaxes and widens the walls of the arteries that supply blood to the penis. This increases the blood flow to the spongy tissue of the penis, causing it to expand and harden into an erection.
After the feelings of sexual arousal have passed, the arteries in the penis should contract (become narrower), which pushes the excess blood out of the penis and returns it to its normal floppy state.
Anything that affects the nervous system or blood flow (or both) can trigger priapism.
Sickle cell anaemia
Sickle cell anaemia is an inherited blood condition where red blood cells develop abnormally. Red blood cells are usually round and flexible and carry oxygen from the lungs to the rest of your body.
However, in people with sickle cell anaemia, the shape and texture of red blood cells can change. They become hard, sticky and crescent-shaped.
In men, it is possible for the hardened blood cells to become trapped in the blood vessels of the penis, leading to a painful and persistent erection.
A number of medications can sometimes disrupt the normal workings of the nerves that help trigger an erection by widening the arteries in the penis.
The nerves essentially ‘forget’ to narrow the arteries after the feelings of sexual arousal have passed, leading to ischaemic priapism.
Medication associated with ischaemic priapism includes:
- oral medications (tablets or capsules) used to treat erectile dysfunction, such as sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra)
- medications for erectile dysfunction that are injected directly into the penis, such as alprostadil
- blood-thinning medications, such as warfarin and heparin
- some types of antidepressants, such as fluoxetine (Prozac) and bupropion
- some medications used to treat high blood pressure (hypertension), such as calcium channel blockers
In addition, some recreational drugs have also been linked to priapism, including:
- methamphetamine (crystal meth)
Less common causes
Less common causes of priapism include:
- thalassaemia – a blood condition similar to sickle cell anaemia
- cancers of the blood, such as chronic leukaemia and multiple myeloma
- cancers that have spread from nearby tissue or organs, such as prostate cancer or bladder cancer, and are disrupting the flow of blood inside the penis
- spinal cord injury
- blood clots
- Fabry disease – a rare, genetic condition that affects the metabolism (the process that converts food into energy)
Priapism can usually be diagnosed by your doctor examining your penis and asking questions about your symptoms and medical history.
For example, you may be asked:
- how long your penis has been erect
- whether your penis is painful or tender
- whether you have a known blood disorder, such as sickle cell anaemia
- whether you are taking a medication that can cause priapism as a side effect, such as sildenafil (Viagra)
- whether you have recently injured your penis or perineum (the area in between your genitals and anus)
- whether you have recently taken recreational drugs, such as cocaine or ecstasy
Blood tests may be needed to find out what is causing your priapism. These can help detect underlying problems with your blood, such as anaemia (a lack of red blood cells), or unusually high numbers of white blood cells, which could be a sign of leukaemia.
Blood tests can also measure the levels of oxygen and carbon dioxide in your blood. Unusually low levels of oxygen and high levels of carbon dioxide would strongly suggest ischaemic priapism (low blood flow).
If non-ischaemic priapism is suspected due to an injury to your genitals or the surrounding area, you may be referred for a scan, such as an ultrasound scan. This will help identify problems with the blood vessels in your penis.
Treatment for priapism will depend on the type of priapism you have.
High blood flow (non-ischaemic) priapism may not need treatment. Many cases get better on their own after a few hours.
If you have injured your genital area, and you have a painful and persistent erection, try holding an ice pack wrapped in a tea towel against your penis. Climbing up and down stairs may also help.
If your symptoms fail to improve, seek immediate medical assistance from your nearest accident and emergency (A&E) department.
You may need surgery to temporarily prevent the flow of blood into your penis.
If you are diagnosed with low blood flow (ischaemic) priapism, aspiration or sympathomimetic injections may be recommended.
Aspiration is the first treatment recommended for priapism.
Your penis is numbed with a local anaesthetic and a small needle and syringe is used to drain blood from your penis.
In some cases, the blood vessels may be ‘washed out’ with sterile water to get rid of any debris. This is known as irrigation.
Aspiration and irrigation usually help relieve painful symptoms and may result in your erection subsiding. However, you may need a number of treatment sessions before this happens.
If your symptoms do not respond to aspiration, the next step is to inject a type of medication known as a sympathomimetic directly into the tissue of your penis.
Sympathomimetics work by squeezing the blood vessels in your penis, helping them push blood out of your penis while also preventing more blood from being pumped in.
A type of sympathomimetic called phenylephrine is usually recommended because it has a lower risk of causing side effects compared with other sympathomimetics.
Side effects of phenylephrine include:
- an increase in blood pressure, which can make you feel dizzy and lightheaded
- tachycardia (rapid heartbeat)
- a noticeably irregular heartbeat
If you have a health condition that could be made worse by an increase in blood pressure, such as heart disease, you will need regular blood pressure checks and electrocardiograms (ECGs). An ECG measures your heart's electrical activity.
Surgery may be recommended if your symptoms fail to respond to aspiration or sympathomimetic injections. There are several surgical procedures available, depending on the type of priapism you have.
If you have ischaemic priapism, shunt surgery may be recommended. This involves implanting a small device called a shunt into your penis to re-route the blood supply out of your penis.
A small number of men who have surgery for priapism experience erectile dysfunction afterwards. However, it is difficult to estimate the exact risk of this occurring because there may be other factors relating to erectile dysfunction, such as priapism itself, which confuse the issue.
If you experience erectile dysfunction after having surgery for priapism, you may need further surgery to treat your erectile dysfunction, such as having artificial implants placed inside your penis.
You should discuss the pros and cons of surgery for priapism with your surgeon beforehand.
If you have non-ischaemic (high blood flow) priapism, a surgical technique called embolisation may be used. It aims to stop the flow of blood into your penis by inserting a small device to block the damaged artery.
Surgical ligation is another method used to treat non-ischaemic priapism. During the procedure, the surgeon ties off the damaged artery to restore normal blood flow to your penis.
Read more about how erectile dysfunction is treated.