Most aneurysms produce no symptoms at all and are found only through imaging tests like ultrasound, CT scans, or MRI. You cannot reliably detect an aneurysm at home, and there is no blood test for one. Checking for an aneurysm means either recognizing warning signs that prompt a medical evaluation or getting screened before symptoms ever appear.
The approach depends on where the aneurysm is. Brain aneurysms, abdominal aortic aneurysms, and thoracic aortic aneurysms each have different symptoms, different imaging methods, and different screening recommendations.
Why Most Aneurysms Go Undetected
An aneurysm is a weakened, bulging section of a blood vessel wall. Small aneurysms often cause zero symptoms for years or even decades. Many are discovered incidentally when a person gets a scan for an unrelated reason. This is what makes them dangerous: the first sign of an aneurysm can be a rupture, which is a medical emergency.
Because symptoms are unreliable for small aneurysms, screening and imaging are the only dependable ways to find them early. Physical self-exams have significant limitations. Even for abdominal aortic aneurysms, which sit relatively close to the surface, a pulsing sensation near the belly button is only noticeable in some cases and can easily be missed or confused with a normal heartbeat.
Symptoms That Suggest a Brain Aneurysm
Small, unruptured brain aneurysms usually cause no symptoms whatsoever. Larger ones can press on surrounding brain tissue and nerves, producing warning signs like pain above and behind one eye, a dilated pupil, double vision, numbness on one side of the face, or seizures. These symptoms develop gradually and often affect only one side.
A ruptured brain aneurysm is unmistakable. The hallmark is a sudden, explosive headache that people consistently describe as the worst headache of their life. It reaches full intensity in a split second, not over minutes or hours. Along with the headache, a ruptured aneurysm typically causes nausea, vomiting, a stiff neck, light sensitivity, vision changes, confusion, or loss of consciousness. This is a 911 situation.
Sometimes an aneurysm leaks slightly before a full rupture. A leaking aneurysm causes a sudden, extremely severe headache that can persist for days to two weeks. This “sentinel headache” is essentially a warning that a full rupture may follow.
Symptoms of an Aortic Aneurysm
The aorta, your body’s largest artery, runs from the heart down through the chest and abdomen. Aneurysms can form in either section.
An abdominal aortic aneurysm that is growing may produce deep, constant pain in the belly or side, back pain, or a throbbing or pulsing sensation near the belly button. Many people feel nothing at all until the aneurysm becomes large. Thoracic aortic aneurysms, located in the chest, are even harder to detect by symptoms alone and are almost always found through imaging.
Imaging Tests Used to Diagnose Aneurysms
The specific test depends on the suspected location.
Brain Aneurysms
CT angiography (CTA) and MR angiography (MRA) are the two primary noninvasive scans for brain aneurysms. Both involve injecting a contrast dye so blood vessels show up clearly on the images. CTA uses X-rays; MRA uses magnetic fields and radio waves. A large meta-analysis found that both methods detect brain aneurysms with about 95% sensitivity, meaning they catch the vast majority. CTA has a slight edge in specificity (96% vs. 89%), so it produces fewer false alarms. In emergency situations where a rupture is suspected, a CT scan of the head is typically the first test performed because it’s fast and widely available.
Abdominal Aortic Aneurysms
Abdominal ultrasound is the standard screening and diagnostic tool. It’s painless, takes about 20 minutes, uses no radiation, and is highly accurate at measuring the diameter of the aorta. An abdominal aortic aneurysm is defined as a dilation of 3.0 cm or greater. A normal abdominal aorta measures roughly 2.0 cm across. Diameters between 2.5 and 2.9 cm (sometimes called aortic ectasia) aren’t classified as aneurysms but do carry a higher risk of progressing to one. CT scans and MRI can also diagnose abdominal aneurysms and provide more detailed images of the size and shape.
Thoracic Aortic Aneurysms
These are typically found with an echocardiogram (an ultrasound of the heart that also shows the upper aorta), a CT scan, or a cardiac MRI. If a standard echocardiogram doesn’t provide enough detail, a transesophageal echocardiogram may be done, where a small probe is guided down the throat to get images from inside the body, closer to the aorta.
Who Should Be Screened
Screening means getting tested before any symptoms appear, and formal guidelines exist mainly for abdominal aortic aneurysms. The U.S. Preventive Services Task Force recommends a one-time abdominal ultrasound for men aged 65 to 75 who have ever smoked (defined as 100 or more cigarettes in a lifetime). For men in that age range who have never smoked, screening is offered selectively based on other risk factors. The task force recommends against routine screening for women who have never smoked and have no family history of the condition.
For brain aneurysms, there are no universal screening guidelines for the general population. Screening with MRA is generally recommended for people with specific risk factors: a family history of brain aneurysm or rupture (particularly two or more first-degree relatives), polycystic kidney disease, or connective tissue disorders. If you have one of these risk factors, ask about screening even if you feel perfectly fine.
Risk Factors That Should Prompt a Conversation
Certain factors raise your odds enough that proactive imaging is worth discussing with a doctor, even without symptoms:
- Smoking history. The single strongest modifiable risk factor for both brain and aortic aneurysms.
- Family history. A first-degree relative (parent, sibling, child) who had an aneurysm or rupture significantly increases your risk.
- Polycystic kidney disease. This genetic condition is strongly associated with brain aneurysms.
- Connective tissue disorders. Conditions like Marfan syndrome and Ehlers-Danlos syndrome weaken blood vessel walls and often require routine aneurysm surveillance.
- High blood pressure. Chronic, uncontrolled high blood pressure accelerates aneurysm growth.
- Age and sex. Abdominal aortic aneurysms are most common in men over 65. Brain aneurysms are slightly more common in women over 40.
What Happens After an Aneurysm Is Found
A small aneurysm that isn’t causing symptoms doesn’t necessarily need immediate treatment. For abdominal aortic aneurysms, monitoring with ultrasound typically starts at least six months after diagnosis, then continues at regular intervals to track whether the aneurysm is growing. During follow-up visits, your doctor will also check and manage conditions like high blood pressure that can make an aneurysm worse.
Brain aneurysms follow a similar watch-and-wait pattern when they’re small and stable. The decision to treat depends on the aneurysm’s size, location, shape, and your overall health. Larger or irregularly shaped aneurysms carry a higher rupture risk and are more likely to be treated. Treatment options exist for both brain and aortic aneurysms, but the threshold for intervention varies by case. The goal of monitoring is to catch growth early so treatment can happen before a rupture, not after one.