An aneurysm is a bulge in the wall of an artery. Aneurysms form when there’s a weak area in the artery wall. Untreated aneurysms can burst open, leading to internal bleeding. They can also cause blood clots that block the flow of blood in your artery. Depending on the location of the aneurysm, a rupture or clot can be life-threatening.


What is an aneurysm?

An aneurysm is a weak or expanded part of an artery, like a bulge in a balloon. Your arteries are large blood vessels that carry oxygenated blood from your heart to other parts of your body. If an area in an artery wall weakens, the force of blood pumping through can result in a bulge or aneurysm.

Aneurysms usually aren’t painful. You might not know you have one unless it ruptures or bursts. If it does, it can be very dangerous or even fatal.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

What are the different types of aneurysms?

An aneurysm can form in any of the arteries in your body. Aneurysms can occur in your heart, abdomen, brain or legs. The location determines the type of aneurysm.

Aortic aneurysms are by far the most common. They form in your aorta, your body’s largest artery. Your aorta carries blood out of your heart. Aneurysms that develop in arteries other than your aorta are called peripheral aneurysms.

Types of aneurysms include:

  • Abdominal aortic aneurysm (AAA): Abdominal aortic aneurysms may form where your aorta carries blood into your abdomen (belly).
  • Cerebral aneurysms: Also called brain aneurysms, these aneurysms affect an artery in your brain. A saccular (or berry) aneurysm is the most common type of cerebral aneurysm. It forms as a sac of blood attached to an artery. It looks like a round berry attached to the artery.
  • Thoracic aortic aneurysm: These aneurysms are less common than AAAs. Thoracic aortic aneurysms form in the upper part of your aorta, in your chest.
  • Carotid aneurysm: Carotid artery aneurysms form in your carotid arteries. These blood vessels bring blood to your brain, neck and face. Carotid aneurysms are rare.
  • Popliteal aneurysm: These develop in the artery that runs behind your knees.
  • Mesenteric artery aneurysm: This type of aneurysm forms in the artery that brings blood to your intestine.
  • Splenic artery aneurysm: These aneurysms develop in an artery in your spleen.

How common are aneurysms?

Unruptured brain aneurysms affect 2% to 5% of healthy people, and about 25% of them have multiple aneurysms. Most brain aneurysms develop in adulthood, but they can also occur in children with mean age of detection around 50 years. The vast majority of brain aneurysms don’t rupture.

Aortic aneurysms become more prevalent with age. Abdominal aortic aneurysms are four to six times more common in those assigned male at birth (AMAB) than those assigned female at birth (AFAB). They affect only about 1% of people AMAB aged 55 to 64. But the incidence increases by 2% to 4% with every decade.


Who is at risk for an aneurysm?

Different types of aneurysms affect different groups. Brain aneurysms affect people AFAB more than those AMAB. Aortic aneurysms more often affect people AMAB.

Abdominal aortic aneurysms occur most often in people who are:

  • Assigned male at birth.
  • Over the age of 60.
  • Smokers.
  • White, although they affect people of any race.

Signs and Symptoms

What are the symptoms of an aneurysm?

In many cases, people don’t know they have an aneurysm. If an aneurysm ruptures (bursts), it’s a medical emergency that requires immediate treatment. Call 911 if you or someone you're with shows signs of a ruptured aneurysm. Symptoms of a ruptured aneurysm come on suddenly. You may feel:

  • Lightheaded.
  • Rapid heartbeat.
  • Sudden, severe pain in your head, chest, abdomen or back.
  • Sudden loss of consciousness following a severe headache.

When an aneurysm causes symptoms, the signs depend on its location. You might notice signs of shock, such as a drop in blood pressure, feeling clammy and “out of it,” and having a pounding heart. Other symptoms of an aneurysm can include:


What are the complications of an aneurysm?

If an aneurysm ruptures, it causes internal bleeding. Depending on the location of the aneurysm, a rupture can be very dangerous or life-threatening. An aneurysm in your neck can cause a blood clot that travels to your brain. If the clot cuts off blood flow to your brain, it causes a stroke. When a brain aneurysm ruptures, it causes a subarachnoid hemorrhage. Some people call this type of stroke a brain bleed. Typically people have what they call the worst headache of their life and then develop other symptoms like limb weakness, headache and trouble speaking.


What causes an aneurysm?

In some cases, people are born with aneurysms. They can also develop at any point during your life. Although the cause of an aneurysm is often unknown, some possible causes include:

Diagnosis and Tests

How is an aneurysm diagnosed?

Many aneurysms develop without causing symptoms. Your healthcare provider may discover it by accident during a routine checkup or other screening.

If you have symptoms that may indicate an aneurysm, your provider will do imaging tests. Imaging tests that can find and help diagnose an aneurysm include:

How will my healthcare provider classify an aneurysm?

Your provider will classify an aneurysm by how large it is and how it forms. The different classifications include:

  • Fusiform aneurysm bulges out on all sides of your artery.
  • Saccular aneurysm causes just one side of your artery to bulge.
  • Mycotic aneurysm develops after an infection (typically in your heart valves) has weakened an artery wall.
  • Pseudoaneurysm or false aneurysm occurs when just the outer layer of your artery wall expands. This can occur after injury to the inner layer of your artery called dissection.

Management and Treatment

How is an aneurysm treated?

If your provider discovers that you have an unruptured aneurysm, they'll monitor your condition closely. The goal of treatment is to prevent the aneurysm from bursting.

Depending on the aneurysm’s type, location and size, treatment can include medication or surgery. Your provider may prescribe medications to improve blood flow, lower blood pressure or control cholesterol. These treatments can help slow aneurysm growth and reduce pressure on the artery wall.

Large aneurysms at risk of bursting may require surgery. You'll also need surgery if an aneurysm bursts. Types of surgery may include:

  • Endovascular aneurysm repair (EVAR): During endovascular surgery, your provider inserts a catheter (thin tube) into the vessel. Through the catheter, the surgeon inserts a graft (section of specialized tubing) to reinforce or repair the artery. For thoracic aneurysms, this procedure is called thoracic endovascular aneurysm repair (TEVAR). If your surgeon has to make a special graft with custom openings, the procedure may be fenestrated endovascular aneurysm repair (FEVAR).
  • Open surgery: In some cases, a surgeon may perform the graft or remove the aneurysm through an incision (open surgery).
  • Endovascular coiling: This procedure treats cerebral aneurysms. The surgeon inserts multiple coils (a spiral of platinum wire) through a catheter to pack the aneurysm. This reduces blood flow to the aneurysm and eliminates the risk of rupture.
  • Microvascular clipping: This type of open brain surgery treats cerebral aneurysms. The surgeon places a metal clip at the base of the aneurysm to cut off blood supply.
  • Catheter embolization: This procedure cuts off blood supply to the aneurysm. The surgeon inserts a catheter into the affected artery, using the tube to place medication or embolic agents that prevent bleeding.


How can I prevent an aneurysm?

Unruptured aneurysms are common. You can’t always prevent them. But you can reduce your risk of developing an aneurysm by maintaining a healthy lifestyle:

Outlook / Prognosis

What is the prognosis (outlook) for people with an aneurysm?

Ruptured aneurysms are a life-threatening emergency. When an aneurysm ruptures in your brain, it causes a stroke. Without immediate treatment, it can be fatal. If you get treatment right away, the outcomes can vary. Many people recover well with rehabilitation and other care.

Healthcare providers usually can help you manage smaller, unruptured aneurysms. Your provider will monitor your condition closely. Medication or surgery can minimize the risk of rupture.

Living With

When should I call the doctor?

You should call your healthcare provider if you experience:

  • Lightheadedness.
  • Rapid heart rate.
  • Sudden, severe pain in your head, chest, abdomen or back.

What questions should I ask my doctor?

You may want to ask your healthcare provider:

  • Am I at risk for developing an aneurysm?
  • Should I have imaging tests to look for aneurysms?
  • How can I prevent an aneurysm from getting worse or rupturing?
  • What lifestyle changes can I make to reduce my risk?

A note from Cleveland Clinic

An aneurysm can occur in any of the arteries in your body. Your provider can monitor and treat an aneurysm to reduce the risk of it bursting. If an aneurysm does rupture, it’s a medical emergency. You need to seek medical attention immediately.

Medically Reviewed

Last reviewed on 04/16/2022.

Learn more about our editorial process.

Appointments 866.588.2264