Aneurysm: what it is, warning signs and screening

Medical disclaimer: This page is general health information for education only. It is not medical advice and is not a substitute for diagnosis or treatment by a qualified health professional. It has not been reviewed by a clinician. In an emergency, call 911 or your local emergency number.

You may have heard the word “aneurysm” after a scan, or after a family member got news from a doctor. This page explains what an aneurysm is, where aneurysms form, who is at higher risk, and which warning signs need emergency care. It also covers screening and how clinicians generally monitor or treat aneurysms. It is part of our library of health conditions.

What is an aneurysm?

An aneurysm is a bulge or “ballooning” in the wall of an artery. Arteries are the blood vessels that carry blood away from the heart. An aneurysm forms where the artery wall is weak, as MedlinePlus explains in its aneurysm overview.

The main danger is that an aneurysm can grow large and burst. A burst is called a rupture. A large aortic aneurysm can also tear the inner wall of the artery, which is called a dissection. The National Heart, Lung, and Blood Institute (NHLBI) says both can be life-threatening.

This page gives general information only. It cannot tell you what your own scan result means or whether your aneurysm needs treatment.

Where do aneurysms form?

Most aneurysms form in the aorta, the main artery that runs from the heart through the chest and abdomen.

• Abdominal aortic aneurysm (AAA): forms in the part of the aorta in the stomach area. NHLBI calls it the most common place for an aneurysm.
• Thoracic aortic aneurysm: forms in the part of the aorta in the chest, above the diaphragm. It is less common than AAA.
• Brain (cerebral) aneurysm: a weak spot on a brain artery that balloons and fills with blood.
• Other arteries: aneurysms can also form behind the knee (popliteal artery), in the intestine (mesenteric artery), and in the spleen (splenic artery).

These locations come from NHLBI’s aortic aneurysm page and the MedlinePlus medical encyclopedia entry on aneurysm. The National Institute of Neurological Disorders and Stroke (NINDS) describes brain aneurysms.

An aneurysm in the brain is a different condition from one in the aorta. Risks, tests, and treatments differ by location.

Who is at higher risk?

Age, smoking, high blood pressure, and family history raise the risk of an aortic aneurysm. NHLBI lists these risk factors:

• Abdominal aortic aneurysms are most common in adults after age 65.
• Men are more likely than women to develop aortic aneurysms.
• Cigarette smoking is one of the main risk factors, especially for abdominal aortic aneurysm.
• High blood pressure is the leading risk factor for thoracic aortic aneurysms.
• Having a parent, sibling, or child with an AAA raises your chance to 1 in 5.
• Marfan syndrome and some other inherited conditions raise the risk of thoracic aneurysms.
• Atherosclerosis, coronary heart disease, and peripheral artery disease also add risk.

The CDC reports that a history of smoking accounts for about 75% of all abdominal aortic aneurysms.

Brain aneurysm risk factors differ in part. NINDS notes that brain aneurysms are more common in women than in men. High blood pressure, smoking, and a close relative with a brain aneurysm also raise risk. You can read more about how high blood pressure affects your arteries and about heart disease and atherosclerosis.

Having a risk factor does not mean you have an aneurysm. Many people with these risk factors never develop one.

Does an aneurysm cause symptoms?

Many aneurysms cause no symptoms until they grow large or rupture.

• Aneurysms can develop and become large before causing any symptoms.
• Abdominal aortic aneurysms often develop slowly over many years, often with no symptoms.
• Aneurysms are often found by chance during imaging tests done for other reasons.

These points come from MedlinePlus and its abdominal aortic aneurysm entry. When symptoms do appear, they depend on where the aneurysm is. An aortic aneurysm may cause a throbbing feeling in the stomach area or pain in the back, chest, or neck. A large brain aneurysm may press on nerves and cause pain behind the eye, vision changes, or numbness.

No symptoms does not mean no aneurysm. Feeling well does not show whether a known aneurysm has grown. Clinicians use imaging tests to check its size.

Warning signs of a rupture: call 911

A ruptured aneurysm is a medical emergency. Call 911 right away if you have these signs.

Aortic aneurysm rupture or tear

• Sudden, severe pain in your stomach area, chest, or back
• Pain that spreads to the groin, buttocks, or legs
• Rapid heart rate, light-headedness, or passing out
• Clammy skin, nausea, or vomiting

These signs are listed by NHLBI and MedlinePlus. MedlinePlus says to call 911 for belly or back pain that is very bad or does not go away.

Brain aneurysm rupture

• A sudden, severe headache, often called “the worst headache of my life”
• Sudden loss of consciousness, or a severe headache with nausea, vomiting, or a seizure

NINDS advises that you call 911 for a sudden, severe headache, especially with other symptoms. MedlinePlus lists the other emergency signs above. Our first aid guide covers what to do while you wait for help.

This list is not complete. Call 911 for any sudden, severe symptom that worries you, even if it is not listed here.

Who should be screened for an abdominal aortic aneurysm?

The US Preventive Services Task Force recommends one-time AAA ultrasound screening for men aged 65 to 75 who have ever smoked.

The USPSTF recommendation was released December 10, 2019, and remains the current version. It sets different advice for different groups.

“Ever smoked” usually means smoking 100 or more cigarettes in your life. The screening test is an ultrasound of the abdomen.

This recommendation applies to people without symptoms. It does not cover brain aneurysms or thoracic aneurysms, and it does not apply if you already have symptoms.

How are aneurysms monitored and treated?

Treatment depends on the aneurysm’s location, size, and growth. Small aneurysms are often watched with repeat imaging instead of repaired right away.

• Monitoring: for a small AAA, providers check the size with ultrasound over months and years, per MedlinePlus.
• Lifestyle and medicines: NHLBI calls quitting smoking the most important part of treatment. Clinicians may also treat blood pressure and cholesterol.
• Open surgical repair: the surgeon removes the aneurysm and sews a graft in its place. Recovery takes about a month.
• Endovascular repair: a stent graft is guided through the blood vessels to the aneurysm. Recovery is usually quicker.
• Brain aneurysm treatment: options include surgical clipping and endovascular coiling, which fills the aneurysm with tiny platinum coils.

MedlinePlus says AAA surgery is most often done when the aneurysm is bigger than 2 inches (5 centimeters) across or growing quickly. Your care team weighs many factors for your own case.

This section describes general approaches only. It is not a treatment plan, and it does not replace advice from the clinicians who know your scans.

Questions to bring to your appointment

These questions can help you understand a new finding. Our guide on preparing for an appointment has more tips.

• Where is my aneurysm, and how big is it?
• How often will I need imaging, and what kind?
• At what size or growth rate would you consider repair?
• Which of my risk factors, such as smoking or blood pressure, can I change?
• Should my parents, siblings, or children be checked?
• Which symptoms mean I should call 911?

This list is a starting point. It does not cover every question for every type of aneurysm.