Quick answer. An abdominal aortic aneurysm (AAA) is a silent bulge in the body’s main artery that usually causes no symptoms until it leaks or ruptures; a simple one-time ultrasound can screen at-risk people, and surgery (EVAR or open repair) is advised once the aneurysm reaches a high-risk size.
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The aorta is the body’s largest artery, carrying blood from the heart down through the abdomen. An abdominal aortic aneurysm is a balloon-like widening of this vessel in the abdomen. Small aneurysms rarely cause problems, but as they grow the wall thins and the risk of rupture rises.
What makes AAA dangerous is that it is usually silent, most people feel nothing until it suddenly leaks or bursts, which is often fatal. That is why screening and monitoring at-risk people is so valuable: a detected aneurysm can be watched and treated safely before it ruptures.
At a glance
| Aneurysm size | Typical approach | Notes |
|---|---|---|
| Under 4.0 cm | Monitor with periodic ultrasound | Low rupture risk; control risk factors |
| 4.0-5.4 cm | Closer surveillance | Watch growth rate; plan ahead |
| 5.5 cm or more (men) | Consider repair (EVAR or open) | Rupture risk rises with size |
| About 5.0 cm or more (women) / rapid growth / symptoms | Consider repair | Lower threshold; urgent if symptomatic |
Why an AAA is a silent risk
Most abdominal aortic aneurysms cause no symptoms and are found by chance on a scan done for another reason. When symptoms do occur, they may include a pulsating feeling in the abdomen, or deep, constant abdominal or back pain.
A ruptured AAA causes sudden severe abdominal or back pain, collapse and life-threatening internal bleeding. Survival after rupture is poor, whereas planned repair of an intact aneurysm is far safer. This contrast is the whole argument for early detection.
Who is at risk and who should be screened?
Risk factors for AAA include:
- Older age, particularly men over 65
- Smoking (current or past), the strongest modifiable risk factor
- High blood pressure and atherosclerosis (hardened arteries)
- A family history of aortic aneurysm
- Male sex (AAA is more common in men)
International guidance commonly recommends a one-time ultrasound screen for men aged 65-75 who have ever smoked, and case-by-case screening for others with risk factors. If you fit these groups, ask your doctor whether screening is appropriate for you.
How AAA is screened and monitored
Screening uses a simple abdominal ultrasound, which is painless, quick, radiation-free and inexpensive. If an aneurysm is found, the approach depends on its size:
- Small aneurysms are monitored with regular ultrasound scans to track growth.
- Larger or fast-growing aneurysms are referred to a vascular surgeon to discuss repair.
Detecting an AAA early allows planned treatment before an emergency occurs.
When is surgery needed?
Repair is generally considered when the benefit of fixing the aneurysm outweighs the risk of the operation. This usually means:
- The aneurysm reaches about 5.5 cm in men (often around 5.0 cm in women)
- It is growing rapidly
- It is causing symptoms or has leaked (an emergency)
Below these thresholds, careful monitoring plus controlling blood pressure and stopping smoking is usually safer than operating. The decision is individualised by a vascular surgeon based on your size, anatomy, age and overall health.
EVAR vs open repair
There are two main ways to repair an AAA:
- Endovascular aneurysm repair (EVAR): A stent-graft is guided into the aorta through small cuts in the groin, sealing the aneurysm from the inside. It is minimally invasive with a shorter hospital stay and faster recovery, but requires lifelong follow-up scans to check for leaks around the graft (endoleaks).
- Open surgical repair: The aneurysm is reached through an abdominal incision and replaced with a graft. It is a bigger operation with a longer recovery but can be very durable, and is often chosen for younger, fitter patients or anatomy unsuitable for EVAR.
Your surgeon will recommend the best option based on your anatomy, fitness and preferences.
Reducing your risk and when to seek help
You can lower aneurysm-related risk by stopping smoking, controlling blood pressure and cholesterol, staying active and attending recommended follow-up scans. Seek emergency care immediately (call 995 or go to A&E) if you have sudden severe abdominal or back pain, a pulsating abdominal mass, fainting or collapse, as these can signal a rupture.
What to expect at a screening or follow-up scan
An abdominal aortic ultrasound is quick and painless. You may be asked to avoid heavy meals beforehand to reduce bowel gas, which can obscure the view. During the scan you lie back while a technician moves a probe over your abdomen to measure the width of the aorta. If no aneurysm is found, no further scans are usually needed unless your risk changes. If a small aneurysm is detected, you will be offered repeat scans at intervals to track any growth, and referred to a vascular surgeon if it reaches a size or growth rate where repair should be discussed.
Reducing your risk between scans
While monitoring continues, the most important step is to stop smoking, which is the strongest modifiable risk factor for both developing and enlarging an aneurysm. Keeping blood pressure and cholesterol well controlled, staying physically active within limits your doctor advises, and eating a heart-healthy diet all support the artery wall and your wider cardiovascular health. Attend every recommended follow-up scan, even when you feel completely well, because an aneurysm typically causes no symptoms until it is dangerously large.
Common questions
Does an aneurysm always need surgery?
No. Small aneurysms are usually monitored rather than operated on, because careful surveillance plus controlling risk factors is safer than surgery at that stage. Repair is generally considered once the aneurysm reaches a high-risk size, grows rapidly or causes symptoms.
Can MediSave help with the cost of repair?
EVAR and open AAA repair are listed surgical procedures, so MediSave can generally be applied to the surgical and inpatient portion, subject to withdrawal limits and after any insurance. Confirm the exact figures and your eligibility with the hospital before treatment.
Related guides
- Best Vascular & Vein Clinics in Singapore — our editorial shortlist
- Varicose veins
- Diabetic foot
- Leg swelling
Sources
- U.S. Preventive Services Task Force – AAA Screening
- SingHealth – conditions and treatments (vascular)
- National University Heart Centre, Singapore (NUHCS)
- NHS – Abdominal aortic aneurysm
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