Aneurysm
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What Is an Aneurysm?

What Is an Aneurysm?
Everyday Health
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Updated on March 24, 2025
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An aneurysm occurs when the walls of a blood vessel or artery in the abdomen, brain, or chest start to weaken and bulge. It’s possible to live with an aneurysm for a long time without symptoms or complications. However, if the aneurysm ruptures, it can be a life-threatening emergency.

Risk factors for an aneurysm include modifiable factors (such as smoking) and unmodifiable factors (such as age).

Types of Aneurysms

Aneurysms have two shapes:

  • Saccular Aneurysm The most common type, this is also known as the berry aneurysm because of the berrylike sac that develops on the Y section of the artery, as well as on the neck and stem.
  • Fusiform Aneurysm This type of aneurysm is less common and has an equal outpouching (bulging) of the artery wall on all sides without a stem. It has a lower risk of rupture.

Abdominal Aortic Aneurysms

The aorta is the main artery in the body, supplying oxygen to the brain, muscles, and cells. An abdominal aortic aneurysm develops in the portion of the aorta located in the abdomen. Abdominal aortic aneurysms affect around 1.1 million people between the ages of 50 and 84 in the United States.

Thoracic Aortic Aneurysms

A thoracic aortic aneurysm forms in the portion of the aorta in the chest, above the diaphragm. Thoracic aortic aneurysms occur in about 6 to 10 of 100,000 people.

Cerebral Aneurysms

Cerebral aneurysms can occur anywhere in the brain, but most form in the major arteries along the base of the skull. All cerebral aneurysms have the potential to rupture and cause bleeding within the brain or surrounding area.

Peripheral Aneurysms

Peripheral aneurysms can occur in the popliteal arteries, located behind the knees, the femoral arteries in the thigh, or the main arteries in the groin and the carotid arteries in the neck.

Peripheral aneurysms in the abdomen, also known as splenic aneurysms, are rare. Those in the legs only affect 0.007 percent of men and fewer women.

About 40 percent of people with a peripheral aneurysm also have an abdominal aortic aneurysm, and 5 to 10 percent of people with an abdominal aortic aneurysm may also have a peripheral aneurysm.

Mycotic and Dissecting Aneurysms

Mycotic and dissecting aneurysms are disease processes by which aneurysms can form, rather than individual types of aneurysms. For example, someone can be diagnosed with a mycotic cerebral aneurysm or a dissecting carotid aneurysm, which affects the carotid artery that carries blood to the head and brain.

  • Mycotic Aneurysm Mycotic aneurysms are caused by a bacterial infection — usually one that originates in the heart, such as endocarditis — and can cause the arterial wall to become infected and dilated. Mycotic aneurysms are rare and represent 0.7 to 3 percent of all aortic aneurysms.

  • Dissecting Aneurysm A dissecting aneurysm occurs when a tear in the inner layer of the aorta causes blood to collect between the inner and middle layers of the aortic wall. This can limit blood flow to the organs or may lead to a rupture of the aorta.

There are two types of dissecting aneurysms:

  • Type A is more common and dangerous. It involves a tear in the part of the aorta where it exits the heart. The tear may also occur in the upper aorta (ascending aorta), which may extend into the abdomen.
  • Type B involves a tear in the lower aorta only (descending aorta), which may also extend into the abdomen.
Aortic dissection is uncommon, occuring in 5 to 30 out of 1 million people each year.

Signs and Symptoms of Aneurysms

Here's a look at the signs of an aneurysm by type. Symptoms vary depending on the location and the severity of the aneurysm.

Abdominal Aortic Aneurysm

Symptoms of an abdominal aortic aneurysm include:

  • A pulsating or throbbing feeling in the abdomen
  • Bloating
  • Pain in the abdomen or back
  • Swelling of the face, neck, or arms
  • Fainting
  • Feeling full after not eating very much

Thoracic Aortic Aneurysm

Symptoms of a thoracic aortic aneurysm include:

  • Pain in the jaw, neck, or upper back between the shoulder blades
  • Pain in the chest or back
  • Wheezing, coughing, or shortness of breath
  • Hoarseness
  • Trouble swallowing

Cerebral Aneurysm

Symptoms of a cerebral aneurysm include:

  • Sudden and severe headache
  • Nausea or vomiting
  • Stiff neck
  • Blurred or double vision
  • Sensitivity to light
  • Seizure
  • Drooping eyelid
  • A dilated pupil
  • Pain above and behind the eye
  • Loss of consciousness
  • Confusion
  • Weakness and/or numbness

Peripheral Aneurysm

Often, peripheral aneurysms do not cause symptoms. When they do, they include:

  • Stomach pain
  • Fainting
  • Feeling full soon after eating
  • Renal aneurysms symptoms include:
  • Uncontrolled high blood pressure.
  • Flank pain.
  • Leg peripheral aneurysms symptoms include:
  • Sudden leg pain
  • Weakness or numbness in your leg
  • Painful or discolored toes

Mycotic Aneurysm

Symptoms of a mycotic aneurysm include:

  • Fever
  • Back pain
  • Severe headache
  • Painful mass in an extremity

Dissecting Aneurysm

Symptoms of a dissecting aneurysm include:

  • Difficulty speaking, loss of vision, or weakness
  • Fainting
  • Shortness of breath
  • Sudden, severe pain in the chest, back, or abdomen

Causes and Risk Factors for an Aneurysm

Aneurysms occur as a result of the blood pushing against the walls of the arteries, along with damage or an injury to the artery’s walls. Various factors may drive their development.

Health conditions associated with elevated aneurysm risk include:

  • High blood pressure (hypertension)
  • High cholesterol
  • Atherosclerosis
  • Obesity
  • Bacterial infections (mycotic aneurysm)

  • Certain genetic conditions, such as Marfan syndrome and Ehlers-Danlos syndrome

Other risk factors for an aneurysm include:

  • Poor diet
  • Smoking
  • Substance abuse disorder, especially of drugs that spike blood pressure
  • Being 55 or older
  • History of physical trauma
Family history also affects aneurysm risk. Those who have a first-degree relative (biological sibling or parent) with an abdominal aortic aneurysm are 10 to 20 times more likely to be affected themselves.

How Does Gender Affect Aneurysm Risk?

Although men are about 4 times more likely than women to have abdominal aortic aneurysms, women have a higher risk of these aneurysms rupturing, regardless of the aneurysm size.

Women are also more likely than men to have brain aneurysms, at a ratio of 3:2.

It’s not entirely clear why women have an increased risk of certain aneurysm events. Estrogen is thought to be a protective factor, putting postmenopausal women at higher risk. Women’s blood vessels are also smaller in diameter than men’s, which may be another factor.

The Link Between Smoking and Aneurysms

Smoking cigarettes is a risk factor for all types of aneurysms.

Smoking damages your heart and blood vessels, which makes you more likely to develop atherosclerosis, or plaque buildup in the arteries. Atherosclerosis is a major risk factor for aneurysm.

Having a plan and knowing where to turn for support are two keys to quitting smoking.

How Is an Aneurysm Diagnosed?

Along with evaluating symptoms, doctors use several tests to diagnose an aneurysm.

Aortic Aneurysm

For abdominal and thoracic aortic aneurysms, a computerized tomography (CT) angiogram can help doctors see the extent of the aneurysm and if there is also a clot in it. Magnetic resonance imaging (MRI) may also be used.

An abdominal ultrasound is recommended to screen men for aortic aneurysms. If an aneurysm smaller than 5.5 centimeters (cm) in diameter is found, your doctor will repeat the ultrasound every 6 to 12 months to make sure it doesn’t grow.

Because symptoms can be vague and look different in women than in men, it’s important to know the warning signs.

In 2019, the U.S. Preventive Services Task Force updated their screening guidelines for abdominal aortic aneurysm for people who do not have signs or symptoms. According to the new recommendations, men between the ages of 65 and 75 who have ever smoked should have a one-time ultrasound screening instead of routine screening of all men in the age group. The task force recommends against routine screening for abdominal aortic aneurysm in women who have never smoked and have no family history of the condition.

Cerebral Aneurysm

Most cerebral aneurysms do not cause symptoms unless they rupture; unruptured brain aneurysms may be detected during medical imaging tests for another condition.

Tests that can be used to detect a brain aneurysm include:

  • CT scan
  • Computerized tomography angiography (CTA)
  • Magnetic resonance imaging (MRI)
  • Magnetic resonance imaging (MRI) or magnetic resonance angiography (MRA)

Peripheral Aneurysm

Peripheral aneurysms are diagnosed with a physical exam, ultrasound testing, and CT scans.

Mycotic Aneurysm

Mycotic aneurysms can be diagnosed with a physical exam, blood tests (to check for an infection), and imaging tests such as CT scans, MRIs, and angiograms.

Dissecting Aneurysm

A dissecting aneurysm is diagnosed with CT scans, MRIs, and echocardiograms.

Aneurysm Treatment

Treatment for an aneurysm depends on its cause, size, location, the factors that put you at risk, and whether the aneurysm has ruptured or is at risk for rupture. Your doctor may decide on a wait-and-watch approach or recommend medication, surgery, or a combination of treatments.

Wait and Watch

Aneurysms that are small and asymptomatic may only require close and careful monitoring, called watchful waiting, with imaging studies performed periodically. The size and rate of growth determines how frequently it should be checked. Most people with an asymptomatic aneurysm less than 4.0 cm (1.6 inches) are advised not to have immediate surgery but to have an ultrasound examination of the abdomen every six months to three years.

Most people with an aneurysm larger than 5.5 cm (2.2 inches) in diameter or one that expands more than 0.5 cm within a six-month period are advised to have it repaired.

Medication Options

No medications can treat an aneurysm, but some may be used to reduce the risk of one worsening:

  • Blood pressure medicines, such as calcium channel blockers and beta blockers, may be prescribed to control blood pressure because hypertension can further weaken an aneurysm and increase the risk for leaking or rupture.
  • Statins, such as atorvastatin (Lipitor), may be used to prevent vasospasm, a condition in which the arteries in the brain narrow after a brain aneurysm rupture.
  • Antiplatelet medication may also be prescribed in patients who undergo surgery to repair cerebral aneurysm.

Surgery Options and Procedures

Treatment for an aneurysm is individual and based on several factors, such as where it is located, how large it is, and if it has ruptured. Because all types of surgery carry risks, and recovery times vary, it’s important to compare the options with your doctor.

Abdominal Aortic Aneurysms and Thoracic Aortic Aneurysms

For large, leaking, or ruptured aortic aneurysms, two types of treatments are available:

  • Open Repair During open repair, the surgeon removes the aneurysm and a portion of the aorta. The section of the aorta is then replaced with a graft.
  • Endovascular Stenting With endovascular stenting, the surgeon threads a catheter into the aneurysm, uses an X-ray to visualize the artery, and inserts a stent graft into the aneurysm. The stent graft allows blood flow through the aorta instead of the aneurysm and reinforces the weakened section of the aorta to prevent a rupture.

Cerebral Aneurysms

If an aneurysm is growing or at risk of rupture or dissection, these are the surgical options:

  • Open Repair (Microvascular Clipping) This surgery involves placing a small titanium clip across the neck of the aneurysm to prevent blood flow.
  • Endovascular Embolization Coils are inserted into the aneurysm to stabilize it and prevent blood flow. The wire causes a blood clot and destroys the aneurysm.
  • Flow Diversion Treatment This treatment closes the aneurysm by using a device made of fine metal wires that guide blood flow through the artery and past the aneurysm.

Peripheral Aneurysm

The treatment for a peripheral aneurysm depends on its location, the condition of the surrounding blood vessels, and other medical issues. Options include:

  • Open Surgical Repair The aneurysm is removed and replaced with a graft made of metal and fabric.
  • Endovascular Repair This is a minimally invasive technique that uses catheters and guidewires to place a stent graft inside the blood vessel.

Mycotic Aneurysm

Mycotic aneurysms are treated with a combination of antibiotics and surgical repair.

Dissecting Aneurysm

Beta-blockers may be prescribed to lower blood pressure and heart rate to a normal range. Surgeries including open repair, coronary bypass graft surgery, endovascular repair, and aortic valve repair may be used.

Preventing Aneurysms

Because aneurysms can cause lifelong health complications or be fatal, it’s important to know your risk factors and your family history. These lifestyle measures may help minimize the risk of developing an aneurysm:

  • Eat healthfully. Avoid foods high in calories, saturated fat, trans fat, and sodium when you can. Instead, focus on whole foods, including plenty of fruits and vegetables, lean protein such as boneless and skinless chicken breast, whole grains, and healthy fats like avocado and nut butter. If you have high cholesterol, eat foods rich in omega-3 fatty acids like fatty fish, nuts, and seeds to help get your levels in a healthy range.
  • Manage hypertension. If you have high blood pressure, work with your doctor to manage it.
  • Exercise regularly. A regular fitness regimen can lower your blood pressure and triglycerides, raise good cholesterol, and, in combination with a healthy diet, help you lose weight.
  • Quit smoking. Over-the-counter smoking cessation aids, prescription medication, and support groups can all help you kick the habit. Talk to your doctor about which options they think would work best for you.

Aneurysm Prognosis

Because many aneurysms cause no symptoms, some people live for years without knowing they have one. The risk of rupture depends on the size, location, and shape of the aneurysm. The outcomes and chance of recovery for an aneurysm depend on the type.

Abdominal Aortic Aneurysms

Abdominal aortic aneurysms of 3 to 4 cm in diameter are considered small, 4 to 5.5 cm are considered medium, and greater than 5.5 cm are considered large. The risk of an aneurysm rupture increases markedly at aneurysm diameters greater than 5.5 cm.

Aortic aneurysm surgery has good outcomes when performed before a rupture or dissection.

However, most people who experience a ruptured abdominal aortic aneurysm do not survive. Of those who make it to the hospital alive, 50 percent do not survive the repair.

Overall, abdominal aortic aneurysms are estimated to cause 4 to 5 percent of sudden deaths.

Thoracic Aortic Aneurysms

Among patients with a thoracic aortic aneurysm who have elective surgery, the five-year survival rate is 85 percent, while those who undergo emergency surgery have a five-year survival rate of 37 percent.

Cerebral Aneurysms

Ruptured brain aneurysms are fatal in about 50 percent of cases, with about 15 percent of people dying before they reach the hospital. Of those who survive, about 66 percent suffer permanent neurological deficits.

Peripheral Aneurysm

The risk of a peripheral aneurysm rupturing is low. However, these types of aneurysms can cause blood clots, which can lead to serious complications such as tissue damage and organ failure.

Mycotic Aneurysm

Nearly all untreated mycotic aneurysms lead to rupture and can be fatal, which is why timely diagnosis and treatment are key.

Dissecting Aneurysm

Untreated Type A dissecting aneurysms have a high mortality rate. The 5-year survival after surgical repair for this type is approximately 70 to 80 percent, while the 10-year survival rate decreases to around 50 percent to 60 percent due to complications such as aortic aneurysms, repeated dissection, and other cardiovascular events.

The five-year survival rate for repaired type B dissections is approximately 75 to 85 percent. Over time, there is an increased risk of developing an aortic aneurysm, repeated dissection, and rupture. Regular imaging and blood pressure control are critical to improving long-term prognosis for this type of dissection.

Complications of Aneurysm

The complications of an aneurysm depend on the type, severity, and if the aneurysm has ruptured.

Abdominal Aortic and Thoracic Aortic Aneurysm

Complications of aortic aneurysms include aortic dissection, regurgitation, rupture, heart failure, cardiac tamponade (a buildup of fluid around the heart), kidney failure, lack of blood flow to the bowels, and injury to the large intestine.

Cerebral Aneurysm

A ruptured cerebral aneurysm can cause stroke, seizures, and permanent brain damage.

Peripheral Aneurysm

Peripheral aneurysms have a low risk of rupture, but they can lead to blood clots, which may block blood flow or travel to other areas of the body, leading to tissue or organ damage. They can also cause pain and swelling if they put pressure on surrounding nerves and veins.

Mycotic Aneurysm

Complications of ruptured mycotic aneurysms include sepsis, multi-organ failure, and amputation.

Dissecting Aneurysm

Complications of dissecting aneurysms include multi-organ failure, stroke, myocardial infarction, renal failure, cardiac tamponade, acute aortic regurgitation, compression of the superior vena cava, and death.

Research and Statistics: How Many People Have an Aneurysm Each Year?

About 6.7 million people in the United States, or 1 in 50, have an unruptured brain aneurysm each year, while 30,000 people in the United States experience a brain aneurysm rupture each year.

Abdominal aortic aneurysms affect around 1.1 million people between ages of 50 and 84 in the United States.

Women are 4 times more likely to experience a ruptured abdominal aortic aneurysm than men, and the risk of a fatal rupture is 3 times higher in women than in men.

About 6 to 10 per every 100,000 people experience thoracic aortic aneurysms, and about 20 percent of those cases are linked to family history.

Disparities and Inequities in Aneurysms

Certain communities have a higher risk for various types of aneurysms.

Black, Hispanic, and Asian Americans have been found to have lower rates of abdominal aortic aneurysm than white and Native Americans.

Compared with white Americans, Black Americans and Hispanics are almost twice as likely to have a brain aneurysm rupture.

While the prevalence of abdominal aortic aneurysm is more common in white Americans than Black Americans, the latter have been found to have worse outcomes after repair.

The Takeaway

  • An aneurysm occurs when a blood vessel or artery in the abdomen, brain, or chest starts to weaken and bulge.
  • Aneurysms don’t always cause symptoms. If they rupture, however, it is considered a life-threatening emergency.
  • Risk factors for aneurysms vary depending on their type and location, but some risk factors include high blood pressure, smoking, atherosclerosis, age, and obesity.
  • Various medications and surgical procedures can repair some aneurysms, though they are more likely to be effective in those that haven’t ruptured. Addressing lifestyle factors such as diet, exercise, and smoking can help prevent some aneurysms from forming.

Common Questions & Answers

What is the main cause of an aneurysm?
Some aneurysms may be congenital, but most are linked to risk factors such as high blood pressure, smoking, obesity, and high cholesterol.
Many aneurysms can go undetected for years because they don’t cause noticeable symptoms. As an aneurysm grows, though, you may notice pain or tenderness to the touch. A ruptured aneurysm, on the other hand, can be painful and may come with symptoms such as dizziness, increased heart rate, and clammy skin.
An unruptured brain aneurysm can cause pain and vision changes. Ruptured brain aneurysms can lead to severe headaches, severe pain behind your eye, confusion, and nausea. Other warning signs of a ruptured brain aneurysm include loss of consciousness, dilated pupils, and seizure.
An estimated 50 to 80 percent of brain aneurysms don’t rupture. Some even shrink over time, never leading to any long-term complications. But it’s important to work with your doctor to monitor your brain aneurysm closely for any signs of growth or rupturing. Lifestyle changes can also help reduce brain aneurysm complications.
Your doctor may recommend surgery for an aneurysm that has ruptured or is at risk of rupturing. While you might be uneasy about the thought of surgery, the survival rate of surgery is far greater than leaving a potentially fatal aneurysm in your body. For example, there’s an estimated 90 percent survival rate for aortic aneurysm surgery performed on unruptured aneurysms.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
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Chung Yoon, MD

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Chung Yoon, MD, is a noninvasive cardiologist with a passion for diagnosis, prevention, intervention, and treatment of a wide range of heart and cardiovascular disorders. He enjoys clinical decision-making and providing patient care in both hospital and outpatient settings. He excels at analytical and decision-making skills and building connection and trust with patients and their families.
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