An aneurysm is a bulge in an artery wall that weakens over time

An aneurysm is a section of an artery that balloons outward because the wall has become thin and weak. Arteries are blood vessels that carry blood away from your heart under pressure. When part of an artery wall loses its strength, the pressure of blood flowing through it pushes that section outward, like a weak spot in a tire. The bulge can stay small and stable for years, or it can grow larger and eventually rupture, which means the artery tears open and bleeds into surrounding tissue.

Most people with an aneurysm have no symptoms and don't know it's there. Many aneurysms are found by accident during imaging tests done for other reasons. The danger comes from the possibility of rupture, which can cause life-threatening bleeding inside your body. Whether an aneurysm needs treatment depends on its size, location, growth rate, and your personal risk factors.

Key Takeaways

  • An aneurysm is a weakened, bulging section of an artery that forms gradually and often causes no symptoms.
  • Aneurysms most commonly occur in the brain, the aorta (the main artery from your heart), and arteries in the legs.
  • A ruptured aneurysm is a medical emergency that causes sudden, severe bleeding and requires immediate hospital care.
  • Doctors find aneurysms through imaging tests like CT scans, ultrasounds, or MRI, usually when scanning for something else.
  • Treatment options range from monitoring with regular imaging to surgery or catheter-based procedures to repair the weakened artery.

Where aneurysms form and why they matter

Aneurysms can develop in arteries throughout your body, but certain locations are more common and more dangerous. A cerebral aneurysm (also called an intracranial aneurysm) forms in an artery inside the brain. If it ruptures, blood spills into the space around the brain, which is a medical emergency called a subarachnoid hemorrhage. A ruptured cerebral aneurysm can cause permanent brain damage or death.

An aortic aneurysm forms in the aorta, the large artery that carries blood from your heart to the rest of your body. This can happen in the chest (thoracic aortic aneurysm) or in the abdomen (abdominal aortic aneurysm). A rupture here causes massive internal bleeding and is often fatal before a person can reach a hospital.

Aneurysms also occur in arteries in the legs, behind the knees, and in other locations. These are generally less immediately life-threatening than brain or aortic aneurysms, but they still require monitoring and may need repair to prevent complications like blood clots or rupture.

Risk factors that make aneurysms more likely

Certain conditions and habits increase the chance that an artery wall will weaken and bulge. High blood pressure is the strongest risk factor because it puts constant stress on artery walls. Smoking damages the inner lining of arteries and weakens the tissue that holds them together. Age also plays a role—aneurysms become more common as you get older, especially after age 60.

Family history matters too. If a close relative had an aneurysm, your risk is higher. Some genetic conditions, like Marfan syndrome or Ehlers-Danlos syndrome, affect how your body builds connective tissue and make aneurysms more likely. Chronic inflammation from conditions like vasculitis can also weaken artery walls over time.

Other contributors include heavy alcohol use, cocaine use, atherosclerosis (buildup of plaque in arteries), and certain infections. Men are more likely to develop aneurysms than women, and the risk increases if you have multiple risk factors at once.

How doctors find an aneurysm

Most aneurysms are discovered by accident. A doctor orders a CT scan, MRI, ultrasound, or angiogram for a different reason—perhaps to investigate headaches, chest pain, or abdominal pain—and the imaging reveals a bulge in an artery. Once found, the aneurysm is measured and its location is documented so doctors can track whether it grows over time.

If you have symptoms that suggest a ruptured aneurysm—sudden, severe headache, sudden chest or back pain, or sudden abdominal pain—emergency imaging is done immediately. A CT scan can show bleeding in the brain or abdomen. An angiogram, where dye is injected into an artery and X-rays are taken, gives doctors a detailed picture of the aneurysm's size and shape and helps them plan treatment.

Screening for aneurysms is not routine for everyone. However, if you have a family history of aneurysm, especially cerebral aneurysm, your doctor may recommend screening with ultrasound or CT. Men over 65 who have ever smoked are sometimes offered screening for abdominal aortic aneurysm.

What happens if an aneurysm ruptures

A rupture is a medical emergency. When an aneurysm tears, blood flows rapidly into surrounding tissue, and blood pressure drops suddenly. In the brain, a ruptured aneurysm causes a thunderclap headache—the worst headache of your life, often described as being hit on the head. Other signs include neck stiffness, sensitivity to light, nausea, vomiting, confusion, and loss of consciousness.

A ruptured aortic aneurysm causes sudden, severe pain in the chest, back, or abdomen, often radiating down the legs. Blood pressure may drop, and you may feel faint or lose consciousness. A ruptured aneurysm in the leg causes sudden, severe pain and swelling.

If you experience any of these symptoms, call 911 immediately. Treatment in the emergency room focuses on stopping the bleeding, stabilizing blood pressure, and preventing further damage. Surgery or catheter-based procedures may be performed urgently to seal the rupture.

Treatment options for unruptured aneurysms

When an aneurysm is found before it ruptures, your doctor will discuss whether it needs treatment now or whether monitoring is safer. This decision depends on the aneurysm's size, location, growth rate, your age, and your overall health. Small, stable aneurysms in less dangerous locations may be watched with regular imaging—typically ultrasound or CT scans every 6 to 12 months—rather than treated right away.

If treatment is recommended, two main approaches exist. Surgical repair, called clipping, involves opening the skull or chest, finding the aneurysm, and placing a metal clip across its neck to stop blood flow into the bulge. Endovascular repair is less invasive: a catheter (thin tube) is threaded through an artery to the aneurysm, and a coil or stent is placed inside to block blood flow and prevent rupture. Endovascular repair often requires a shorter hospital stay and recovery time than surgery.

Your doctor will explain the risks and benefits of each approach for your specific situation. The goal is to prevent rupture while minimizing the risks of the treatment itself.

Living with an aneurysm diagnosis

Learning that you have an aneurysm can be frightening, especially if you have no symptoms. It helps to remember that many aneurysms never rupture and can be managed safely with monitoring. Your role is to attend follow-up appointments, get imaging tests on schedule, and report any new symptoms to your doctor immediately.

Managing risk factors becomes especially important. If you smoke, quitting reduces the pressure on your artery walls and slows aneurysm growth. Controlling high blood pressure through medication and lifestyle changes protects your arteries. Limiting alcohol, managing stress, and staying physically active all support artery health.

Keep a list of your aneurysm details—its location, size, and the date it was found—and share this information with any new doctors you see. If you travel or move, arrange for your imaging records to follow you so your new doctor can compare scans and track any changes. Some people wear medical alert identification stating they have an aneurysm, which can be helpful in an emergency.

Frequently Asked Questions

Can you feel an aneurysm before it ruptures?

Most unruptured aneurysms cause no symptoms at all. Some people report a dull headache or neck pain if a cerebral aneurysm is large and pressing on nearby tissue, but this is uncommon. A ruptured aneurysm, by contrast, causes sudden, severe symptoms and is a medical emergency.

Does having an aneurysm mean it will definitely rupture?

No. Many aneurysms remain stable and never rupture. The risk of rupture depends on size, location, and growth rate. Small aneurysms in stable locations have a low rupture risk, which is why doctors often recommend monitoring rather than immediate surgery.

Can stress or exercise cause an aneurysm to rupture?

Sudden physical exertion or extreme stress can temporarily raise blood pressure and may increase rupture risk in someone with a large, fragile aneurysm. However, normal daily activity and moderate exercise are generally safe. Your doctor can advise you on what activities are appropriate for your specific situation.

What is the difference between an aneurysm and a stroke?

A stroke occurs when blood flow to the brain is blocked by a clot or when a blood vessel in the brain ruptures and bleeds. A ruptured cerebral aneurysm causes a type of stroke called a hemorrhagic stroke. An unruptured aneurysm does not cause a stroke unless it ruptures.

How often do I need imaging if I have an unruptured aneurysm?

The schedule depends on the aneurysm's size and stability. Small, stable aneurysms may be imaged every 1 to 2 years. Larger aneurysms or those showing growth may need imaging every 6 months or more frequently. Your doctor will recommend a schedule based on your individual case.