Medically Reviewed By William C. Lloyd III, MD, FACS

What is an aneurysm?

An aneurysm is an abnormal widening or ballooning of an artery due to weakness in the wall of the blood vessel. Aneurysms are dangerous because they may burst (rupture), spilling blood in the area surrounding the blood vessel.

An aneurysm can occur in any artery or vein in the body but commonly occurs in the aorta, the largest artery in the body, which leads from the heart into the abdomen. Aortic aneurysms are most commonly found in the abdominal cavity (known as abdominal aortic aneurysm, AAA) but may also occur in the chest or thoracic cavity (known as thoracic aortic aneurysm, TAA).

Brain aneurysms occur in about 1 in 50 people in the United States, according to the Brain Aneurysm Foundation. Statistically, aortic aneurysms are more common in people who are white; male; older than 60 years; and have high blood pressure, atherosclerosis, or a family history of aneurysm. Cigarette smoking is also a known risk factor for the development of aortic aneurysm. In the U.S., an estimated 1.4% of men aged 50 to 84 years have an AAA larger than 3 cm.

The signs and symptoms of an aneurysm depend on its location. The disease course varies among individuals. Some people with an aneurysm experience no symptoms, but if the aneurysm ruptures, internal bleeding occurs. This can potentially cause pain, low blood pressure, a rapid heartbeat, and lightheadedness.

When an aneurysm bursts inside the skull (intracranial aneurysm), individuals report “the worst headache of their life” followed by a rapidly progressive decline in alertness, mental function, and other neurologic functions. If the aneurysm occurs near the surface of the skin, people often feel pain and swelling with a throbbing mass.

Fortunately, aneurysms can be treated successfully with a range of options, such as lifestyle changes, high blood pressure management, or surgery.

Left untreated, an aneurysm may rupture. Rupture of an artery can result in life-threatening bleeding. Seek immediate medical care (call 911) for symptoms of a ruptured aneurysm, such as severe back pain, sudden severe headache, rapid heart rate, difficulty swallowing, blurred vision, cold skin, or loss of consciousness.

What are the different types of aneurysm?

An aneurysm can occur in any artery or vein, but they most commonly occur in the aorta, intracranial arteries, and peripheral arteries. Aneurysms in veins (venous aneurysm) are rare. Common types of aneurysms include:

  • Aortic aneurysm, including abdominal aortic aneurysm (AAA) and thoracic aortic aneurysm (TAA). TAAs involve the upper part of the aorta in the chest cavity where the aorta leaves the heart. AAAs involve the lower portion of the aorta, below the diaphragm and before the aorta splits into the left and right iliac arteries going to the legs. Abdominal aortic aneurysms are the most common type of aneurysm. 
  • Brain aneurysm, also known as a cerebral or intracranial aneurysm. Brain aneurysms can occur in any blood vessel within the brain. An aneurysm that ruptures can lead to hemorrhagic stroke. The Brain Aneurysm Foundation estimates 6.5 million people (1 in 50) in the United States have an unruptured brain aneurysm.
  • Peripheral artery aneurysm, including aneurysms in an artery of the leg, groin, spleen, or intestine. The risk of aneurysm rupture is low.  

Aneurysms can also occur in the coronary arteries (supplying the heart muscle) and carotid arteries (supplying the brain).

Dissection and rupture 

The aortic artery wall has three layers. A tear in one of the inner layers is called a dissection, which causes blood to be redirected between the inner and middle layers. This also disrupts normal downstream blood flow throughout the body.

Rupture of an aortic aneurysm is an opening across all three layers. It is a complete dissection. Most people do not survive aortic aneurysm dissections or ruptures, but it is possible with emergency access to perform a lifesaving surgical repair.

What are the symptoms of an aneurysm?

Aneurysms can develop slowly over many years and may never pose a health threat. Many people have no symptoms, while others may experience a number of symptoms that vary in intensity among individuals depending on the location, rate of growth, and size of the aneurysm.

Common symptoms of an intracranial aneurysm

Brain aneurysms typically do not produce symptoms. However, if an intracranial aneurysm ruptures, any of these aneurysm symptoms may occur and can be severe:

  • Blurred or double vision

  • Confusion or loss of consciousness for even a moment

  • Dilated pupil 

  • Drooping eyelid

  • Increased sensitivity to light

  • Nausea with or without vomiting

  • Pulsing sensation

  • Seizures and tremors

  • Severe headache

  • Stiff neck

Common symptoms of an aortic aneurysm

An unruptured aortic aneurysm will likely not cause symptoms. The most common symptoms of a dissected or ruptured aortic aneurysm include:

Common symptoms of a peripheral artery aneurysm

Peripheral artery aneurysms do not typically cause symptoms and do not usually rupture. However, they can lead to arterial blood clots. The most common symptoms of a blood clot in the leg are:

  • Cool and pale skin (from reduced blood flow)

  • Numbness

  • Sudden pain in the area

Serious symptoms that might indicate a life-threatening condition

In some cases, aneurysms can be life-threatening. Seek immediate medical care (call 911) for any of these life-threatening symptoms including:

What causes an aneurysm?

Aneurysms are caused by weakness in the wall of a cerebral (brain) artery or vein, aortic artery, or peripheral artery. The disorder may result from defects present at birth (congenital); from underlying conditions, such as hypertensive vascular disease and atherosclerosis (buildup of fatty deposits in the arteries); or from previous trauma to the area of the aneurysm.

What are the risk factors for an aneurysm?

Several factors increase the risk of developing an aneurysm. High blood pressure, high cholesterol levels, and cigarette smoking raise the risk of certain types of aneurysms.

High blood pressure and smoking are known to contribute to the formation of abdominal aortic aneurysms. Atherosclerotic disease (cholesterol buildup in arteries) may also lead to the formation of some aneurysms. Pregnancy is often associated with the development and rupture of splenic artery aneurysms.

Inherited conditions that affect the connective tissues of the body, such as Marfan syndrome, also increase your risk of developing certain types of aneurysms.

Risk factors for aneurysm include:

  • Advanced age

  • Atherosclerosis (buildup of plaque on the walls of the coronary arteries)

  • Caucasian race

  • Estrogen deficiency from menopause

  • Family history of aneurysm

  • Genetic diseases of connective tissue, such as Marfan syndrome and Ehlers-Danlos syndrome 

  • High blood pressure

  • Male sex (assigned at birth) 

  • Preexisting blood vessel malformations

  • Smoking or other tobacco use. (An estimated 90% of people diagnosed with an abdominal aortic aneurysm have smoked cigarettes during their lifetime.) 

Seeing a primary care doctor regularly will help determine whether you are at risk of developing an aneurysm. If you have a higher likelihood of developing an AAA, you may want to discuss your need for screening and the best approach to controlling your risk factors. Keep in mind that not all people with risk factors will get an aneurysm; they only increase the chance of developing one. Typically, the more risk factors you have, the greater the likelihood.

How do you prevent an aneurysm?

You may be able to lower your risk of an aneurysm by controlling and minimizing your risk factors. The most significant risk factor you can control is smoking. For abdominal aortic aneurysm (AAA), people who currently smoke are 3 to 12 times more likely as people who have never smoked to develop an AAA, depending on the years and quantity of smoking. Quitting smoking is vital to lowering the risk of aneurysm.

In addition to not smoking, other steps you can take that may help decrease your risk include:

  • Getting regular physical activity

  • Keeping your cholesterol at a healthy level with medication if needed

  • Knowing your family history of aneurysm. Although this does not reduce your risk of aneurysm, a known family history may help you and your doctor understand your need for aneurysm screening and monitoring.

  • Maintaining a healthy weight

  • Maintaining normal blood pressure with medication if needed

  • Reducing the amount of cholesterol and fat in your diet. Eating fruits and vegetables more than three times a week is beneficial.

What are the diet and nutrition tips for an aneurysm?

High blood pressure and high cholesterol are risk factors for aneurysms and other vascular diseases. One way to control blood pressure and cholesterol is through a healthy diet. A nutritious, healthy diet includes:

  • Fish at least once a week and preferably twice a week. One of the main benefits of fish is its abundance of essential omega-3 fatty acids, which are protective for the heart and brain. If you cannot tolerate fish, supplement your diet with purified fish oil.

  • Food rich in potassium, which helps manage blood pressure by releasing more sodium (salt) from your body. A healthy diet already has enough daily potassium. Your doctor may prescribe a high-potassium diet or supplements if you are low in potassium. 

  • Fresh food rather than processed food

  • Fruits and vegetables at least three times a week

  • Lean cuts of beef and other meats

  • Legumes, which include peas, beans, lentils, soybeans and peanuts

  • Low-fat dairy products

  • Low-sugar foods and drinks

  • Nuts and seeds

  • Small amounts of salt (less than 1,500 milligrams [mg] per day)

  • Whole grains

It is also a good idea to limit alcoholic beverages: one drink per day for females and two drinks per day for males.

Ask your healthcare provider for guidance before making significant changes to your diet or supplementing it.

What are some conditions related to an aneurysm?

Conditions related to aneurysm include:

  • Aortic dissection, when the innermost layer of the wall of the aorta opens up, spilling blood in between the inner and middle layers and disrupting normal blood flow through the aorta and arteries connected to the aorta. Dissection is life-threatening, and can also lead to complete rupture. 

  • Hemorrhagic stroke, when a ruptured brain aneurysm bleeds into the brain

  • Occlusive peripheral arterial disease, a potential complication of peripheral artery aneurysms of the leg or groin. Blood clots can develop within the aneurysm. If the clot breaks off, it can move to smaller arterial branches and block blood flow to the lower limb. 

How do doctors diagnose an aneurysm?

Doctors use imaging tests to diagnose aneurysms. The type of imaging test may depend on the location of the suspected aneurysm.

Diagnostic imaging tests for aneurysm

Common imaging tests include:

  • Chest X-ray

  • CT angiography. This test uses X-rays to create highly detailed images of the inside of the body, including the brain. The radiologist injects a dye into a vein to create contrast between the circulatory system and other body tissues, which makes it easier to see blood vessel abnormalities.

  • MRA (magnetic resonance angiography). This test is an MRI with a contrast dye. It uses a different technology from a CT scan to create detailed images of blood vessels. It does not involve X-rays, but it typically takes longer than a CT scan.

  • Ultrasound. Doctors use abdominal ultrasound for abdominal aortic aneurysms and a chest ultrasound (echocardiogram) for thoracic aortic aneurysms.


Aneurysm screening

People who are at high risk of aneurysm may be candidates for screening tests. These are imaging tests in the absence of any signs or symptoms of aneurysm. There are guidelines for different types of aneurysms:

  • For abdominal aortic aneurysms (AAAs), men older than 65 who smoked or who have a first-degree family history of abdominal aortic aneurysm (AAA) may be candidates for AAA screening by ultrasound, even if they have no symptoms. Men of this age group who have never smoked may also qualify for screening. 

The U.S. Preventive Services Task Force (USPSTF), which sets screening guidelines for a wide range of conditions, states there is not enough evidence to advise AAA screening for women aged 65 to 75 years with a history of smoking or a family history of AAA. Talk with your doctor about whether you are a candidate for AAA screening based on your age and other risk factors. The USPSTF guideline states:

  • For brain aneurysms, individuals with a personal or family history of brain aneurysm or hemorrhagic stroke may be candidates for screening. People with certain genetic syndromes that increase the risk of aneurysm, such as Marfan syndrome, may also be candidates. 

The benefits of aneurysm screening may not outweigh the risks, such as additional invasive testing procedures and surgery to treat the aneurysm. Discuss the benefits and risks of aneurysm screening with your healthcare provider, in the context of your personal risk factors and potential outcomes if you were to be diagnosed with an aneurysm.

How is an aneurysm treated?

Treatment of an aneurysm depends on the size, location and type of aneurysm. An expanding or enlarging aneurysm in the aorta often requires emergency treatment, and doctors generally recommend surgery. The type of surgery and when it is needed it will depend on the symptoms and the size and type of aneurysm.

Some people may have endovascular stent repair. A stent is a tiny tube placed within a blood vessel to keep the vessel open or reinforce its wall.

Doctors often take a wait-and-see approach to small aneurysms that are not life-threatening. Such observation requires regular medical care and testing. Doctors use imaging tests to monitor potential growth of aneurysms. The decision of whether to perform surgery requires balancing the risk of surgical complications against the risk of complications from the aneurysm itself.

Common treatments of aneurysm include:

  • Blood pressure management

  • Control of risk factors

  • Observation and monitoring

  • Surgical repair of the aneurysm

How does an aneurysm affect quality of life?

People with an unruptured aortic or brain aneurysm can live a lifetime and never experience any difficulties due to it. In fact, most people do not know they have an aneurysm. Aneurysms may be diagnosed incidentally during investigation of an unrelated health problem, by screening tests due to risk factors, or by experiencing signs and symptoms of an aneurysm.

For people with small or slowly growing aneurysms with a low risk of bleeding or rupture, doctors often take a watchful waiting approach to treatment. Your doctor will see you at regular intervals to monitor the aneurysm, suggesting treatment only when the aneurysm reaches a certain size or growth rate. He or she will likely prescribe lifestyle changes and perhaps medication to manage risk factors, such as high blood pressure.

For some people, watchful waiting is very stressful and can impair quality of life. Worrying about the aneurysm growing or bursting may affect your daily activities. It is important to openly discuss your concerns with your doctor. Learning more about your aneurysm and prognosis can help. Questions to ask your doctor may include:

  • What is the risk of the aneurysm growing?

  • What is my prognosis?

  • Are there lifestyle changes I can make to reduce the risk of the aneurysm growing?

  • For which symptoms should I call you or seek medical attention (in between regular visits)?

  • Do I have any restrictions on the types of exercise I can do? 

  • What type of treatment options do I have?

  • When can I have surgery to repair the aneurysm? How will you know when the time is right?

  • What type of surgical repair do you recommend? 

  • Am I a candidate for minimally invasive surgery?


Coping tips and lifestyle changes 

In addition to following your healthcare provider’s instructions and taking all medications as prescribed, you can reduce the risk of the aneurysm growing by:

  • Eating a heart-healthy diet that includes potassium and fiber and drinking plenty of water

  • Exercising at least 30 minutes a day

  • Limiting alcohol consumption to one drink a day for females, two a day for males

  • Limiting the amount of sodium (salt) you eat (less than 1,500 milligrams [mg] per day)

  • Maintaining a healthy body weight

  • Quitting smoking

  • Reducing stress

What are the potential complications of an aneurysm?

You can help minimize your risk of serious complications by following the treatment plan you and your healthcare professional design specifically for you. Complications of aneurysm include:

  • Blood clots

  • Compression of nerves or other adjacent structures, causing weakness and numbness (occurs most commonly with aneurysms that develop in the artery behind the knee)

  • Hypovolemic shock (a state of low blood pressure caused by bleeding or other fluid loss)

  • Organ failure

  • Rupture of the aneurysm

  • Severe internal bleeding

  • Stroke

What is the survival rate and prognosis for aneurysms?

Most aneurysms grow slowly and do not cause a problem. If a diagnosed aneurysm is growing quickly, surgical repair of the aneurysm is an effective treatment in most cases. However, large aneurysms and those growing quickly have an increased risk of rupture and life-threatening bleeding.

Aortic aneurysm survival

The survival rate of ruptured abdominal aortic aneurysms (AAAs) is low, but the number of deaths from ruptured AAAs has declined by 68% from 20 years ago. This is perhaps due to increased awareness, diagnosis, and treatment interventions, as well as declining smoking rates.

Brain aneurysm survival

An estimated 6.5 million people (1 in 50) in the U.S. have a brain aneurysm, and up to 80% of these do not rupture, according to the Brain Aneurysm Foundation. About 30,000 people a year experience a ruptured brain aneurysm. Ruptures are fatal in half of all cases due to bleeding and brain damage. Survivors typically have permanent nervous system damage and disability. An accurate and early diagnosis of brain aneurysm greatly improves the prognosis. Talk with your doctor about your risk factors and treatment options.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Nov 7
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