An aneurysm builds quietly, in the arteries of the brain or in the abdominal aorta, usually without symptoms. How common it is, who gets checked and what a full-body MRI can show.
What an aneurysm is, and why it stays quiet
An artery is a tube with an elastic wall. If the wall gives way in one spot, it bulges. That bulge is an aneurysm. Two places matter most: the arteries in the brain and the abdominal aorta, the main artery in your belly.
An aneurysm usually causes no symptoms (Dremel et al., 2026; G-BA). If you have one, you most likely won’t feel it. That’s the heart of the matter: it often comes to light only when someone takes scans for another reason. If the wall tears, it’s an emergency. That happens far less often than aneurysms occur.
What an aneurysm looks like, schematically
Three vessel sections compared: healthy, abdominal aorta, brain artery.
How common aneurysms are, and who is at higher risk
In the brain. A review of 162 studies estimates that about 4 in 100 adults around the age of 50, with no underlying conditions, have a brain aneurysm: 3.9% (Dremel et al., The Lancet Neurology, 2026). The previous review, in 2011, put the figure at 3.2% (Vlak et al.). Newer studies find more, partly because imaging now picks up small aneurysms better. Roughly three in four of the aneurysms found are smaller than 5 millimetres.
Risk is higher if you smoke (1.4 times as common), have high blood pressure (1.6 times) or are a woman (1.9 times). Where there’s a family history of a brain aneurysm or a brain bleed caused by one, the share was 7.9%.
In the abdominal aorta. This one mostly affects men over 65. Germany’s Federal Joint Committee (G-BA), the body that decides which screening the statutory health insurers pay for, assumes that 4 to 8% of men over 65 are affected, and 0.5 to 1.5% of women in that age group (G-BA, 2016). The main cause is hardening of the arteries. The usual risk factors are high blood pressure, smoking, raised blood fats, older age and being male. Smoking and blood pressure are two you can keep an eye on yourself.
| Brain aneurysm | Abdominal aortic aneurysm | |
|---|---|---|
| Where | Brain arteries, often at branching points | Main artery in the abdomen |
| How common | About 4% of adults around 50 with no underlying conditions | 4 to 8% of men over 65, 0.5 to 1.5% of women |
| More common in | Women, smokers, high blood pressure, family history | Men, older age, smokers, high blood pressure, raised blood fats |
| Structured screening | None | Germany: one-off ultrasound for men from 65. Switzerland: no programme |
Who gets checked, and who doesn’t
The figures in the table come from different groups, so you can’t compare them one to one.
For brain aneurysms, neither Switzerland nor Germany has structured screening. For the abdominal aorta, the two countries differ. In Germany, men aged 65 and over on statutory health insurance are entitled to a one-off ultrasound that measures the width of the aorta (G-BA; gesund.bund.de). The G-BA found proven benefit for this group, and no sign of benefit for women (G-BA, 2016). Switzerland has no such programme. There, ultrasound is only recommended for people at higher risk from 65, for example smokers (USZ; Kantonsspital Baden). For women and for men under 65 there’s no programme in either country. Whether a targeted search in high-risk groups would help is something researchers want to look at further (Dremel et al., 2026).
An aneurysm usually goes unnoticed. It gets found where someone looks on purpose.
What a full-body MRI can show, and what it can’t
A full-body MRI examines, in one appointment, the brain, chest, aorta and major vessels, all the major organs, the spine and the lymph nodes, among other areas. It uses no radiation and no contrast agent. Aneurysms can show up along the way, in the aorta as well as in the brain arteries.
After the scan you get a doctor-reviewed report and talk it through in a consultation with a doctor. If something needs a closer look, the doctor tells you the next step, such as a referral to a specialist.
Limit
An MRI can show that something is there. It doesn’t tell you how an aneurysm will develop.
A finding doesn’t automatically mean something has to be done. Small aneurysms of the abdominal aorta are usually monitored with regular checks, and surgery is only recommended above a certain size (G-BA). The researchers behind the Lancet review also stress that not every brain aneurysm should be treated as a precaution (Dremel et al., 2026). For the abdominal aorta, experts estimate that about every second aneurysm found through screening is harmless (German Medical Association and KBV, 2023). A finding can still be unsettling. That’s what the consultation is for.
Limits matter. Very small aneurysms can slip past an MRI too. It replaces neither the ultrasound of the abdominal aorta that men are entitled to from 65 nor a medical assessment when you have symptoms, and it’s no way to buy time in an emergency.
Conclusion
Aneurysms are no niche topic, and they rarely announce themselves. Structured searching hardly exists: not for the brain, and for the abdominal aorta only for a narrow group, men from 65 in Germany and higher-risk people from 65 in Switzerland. If you still want to know how your aorta and brain look, you can take that into your own hands. A full-body MRI examines both areas and can show aneurysms if there are any. It has limits, and it doesn’t replace a doctor.
Frequently asked questions
Would I notice if I had an aneurysm?
Usually not. An aneurysm mostly causes no symptoms, so it’s often found on scans taken for another reason (The Lancet Neurology, 2026). If you have sudden, very severe symptoms, call emergency services: 112 in Germany, 112 or 144 in Switzerland.
Is there a screening programme for aneurysms?
Not for brain aneurysms, in either Switzerland or Germany. For the abdominal aorta, Germany offers a one-off ultrasound to men from 65 on statutory health insurance (gesund.bund.de). In Switzerland, ultrasound is only recommended for people at higher risk from 65, such as smokers (USZ). For women and men under 65 there’s no programme in either country.
Do aneurysms affect women too?
Yes. Brain aneurysms are more common in women than in men, 1.9 times as common in the Lancet review (Dremel et al., 2026). The abdominal aorta is affected less often. Because the G-BA saw no proven benefit of screening for women there, Germany has no programme for them (G-BA, 2016).
What happens if an aneurysm is found?
You get a doctor-reviewed report and talk it through in a consultation with a doctor. A specialist decides what happens next. It’s often not an operation: small aneurysms are frequently just monitored.
Does an MRI find every aneurysm?
No. Very small aneurysms can go undetected, and whether an aneurysm shows up also depends on its size and position. A clear result is a snapshot, not a guarantee for the future.
Sources
- Dremel et al., The Lancet Neurology 2026: how common brain aneurysms are, risk factors and size, review of 162 studies.
- Vlak et al., The Lancet Neurology 2011: earlier estimate of how common they are (3.2%).
- The Lancet Neurology 2026, commentary on Dremel et al.: aneurysms are mostly found by chance on scans taken for another reason.
- G-BA, screening for aneurysms of the abdominal aorta: entitlement for men from 65, procedure, monitoring of small aneurysms.
- G-BA, press release 2016: how common, risk factors for the abdominal aorta, assessment of benefit for men and women.
- G-BA, press release on the guideline: healthy abdominal aorta, usually under 3 centimetres wide.
- Barmer, screening for abdominal aortic aneurysms: above 3 centimetres, it’s called an abdominal aortic aneurysm.
- gesund.bund.de, early detection of diseases: list of early detection exams paid for by statutory insurers in Germany, as of 23 April 2026.
- University Hospital Zurich, aneurysm: in Switzerland, ultrasound of the abdominal aorta is only recommended for people at higher risk from 65.
- Kantonsspital Baden, trade magazine 2020: Switzerland has not established a national screening programme.
- German Medical Association and KBV, patient information 2023: estimate that about every second aneurysm of the abdominal aorta found through screening is harmless.
