Most aortic aneurysms are found through imaging tests, not physical symptoms. The standard screening method is an abdominal ultrasound, a painless test that takes about 20 minutes and can measure the width of your aorta with high accuracy. Because aneurysms often grow silently for years, knowing who should be screened and what the different tests reveal is critical for catching one before it becomes dangerous.
Who Should Be Screened
The U.S. Preventive Services Task Force recommends a one-time abdominal ultrasound screening for men aged 65 to 75 who have ever smoked. This is the strongest screening recommendation and carries a “B” grade, meaning there’s high confidence the benefit outweighs the harm. For men in the same age range who have never smoked, screening is offered selectively based on other risk factors like family history or high blood pressure.
For women, the picture is less clear. The Task Force recommends against routine screening for women who have never smoked and have no family history of aneurysm. For women aged 65 to 75 who have smoked or do have a family history, the evidence is currently considered insufficient to make a firm recommendation either way. That said, many vascular specialists will still order screening for women with multiple risk factors.
People with genetic connective tissue disorders face a different timeline entirely. Conditions like Loeys-Dietz syndrome and Marfan syndrome can cause aneurysms at much younger ages and at smaller aortic diameters. Guidelines recommend that people with certain high-risk genetic mutations begin echocardiographic monitoring in the first decade of life. If you have a first-degree relative who experienced an aortic dissection or aneurysm, especially before age 65, bring this up with your doctor regardless of your own age or smoking status.
Abdominal Ultrasound: The Primary Screening Tool
Ultrasound is the go-to test for detecting abdominal aortic aneurysms. It uses sound waves to create a live image of your aorta, requires no radiation, and involves no needles or contrast dye. A technician applies gel to your abdomen and moves a handheld probe across it. The specificity of ultrasound is extremely high, between 98% and 100%, meaning a negative result is very reliable. Sensitivity in screening studies ranges from about 57% to 100% depending on the study population and technique, though it performs best when the test is specifically looking for aneurysms rather than scanning for multiple conditions at once.
You’ll need to fast for 8 to 10 hours before the test. Food in your stomach and intestines can obstruct the view of your aorta, so most appointments are scheduled in the morning. The test itself is painless and results are typically available within a few days.
Medicare covers a one-time abdominal aortic aneurysm screening for people considered at risk, defined as men between 65 and 75 who have smoked at least 100 cigarettes in their lifetime, or anyone with a family history of abdominal aortic aneurysm. You’ll need a referral from your healthcare provider to qualify.
CT and MRI for More Detailed Imaging
When ultrasound detects an aneurysm or when a thoracic (chest) aneurysm is suspected, CT angiography and MR angiography become the primary tools. CT scans offer slightly higher sensitivity than ultrasound in screening studies, with detection rates between 83% and 97%, and they produce detailed cross-sectional images that show the exact size, shape, and location of an aneurysm. They also reveal whether the aneurysm is affecting nearby structures or showing signs of complications.
The American College of Radiology rates both CT angiography and MR angiography as “usually appropriate” for initial imaging of thoracic aortic aneurysms. Standard ultrasound can visualize the aortic root and the first portion of the ascending aorta, but it can’t see the full thoracic aorta because the lungs and ribs block the sound waves. That makes CT or MRI essential for aneurysms in the chest.
CT is often preferred when speed matters or when planning for a surgical repair, because it captures highly detailed images in seconds. MRI avoids radiation exposure and is a good alternative for patients who need repeated imaging over time, though it takes longer and isn’t ideal for people with certain metal implants.
Can a Physical Exam Detect an Aneurysm?
Sometimes. A doctor pressing on your abdomen may feel a pulsatile mass near your navel, which can signal an enlarged abdominal aorta. However, physical examination is unreliable for smaller aneurysms and becomes even less accurate in patients with obesity. A palpable pulsation typically indicates the aneurysm is already large. Physical exam cannot detect thoracic aneurysms at all. It should never be relied on as a substitute for imaging.
Symptoms That Call for Immediate Testing
Most aneurysms cause no symptoms until they’re large or beginning to leak. As an aneurysm grows, it can press on surrounding structures, producing a range of warning signs depending on its location. These include chest, back, or abdominal pain, a throbbing sensation in the abdomen, difficulty swallowing, pain while breathing, face or arm swelling, and feeling full after eating only a small amount.
If an aneurysm begins to tear or rupture, symptoms become severe and sudden. The hallmarks are intense, sharp pain in the back, chest, or abdomen that comes on without warning, along with dizziness, lightheadedness, and a rapid heart rate. Because the aorta supplies blood to the entire body, a tear can also cause pain, numbness, or stroke-like symptoms in the arms or legs if blood flow to those areas is disrupted. This is a medical emergency requiring immediate evaluation, typically with a CT scan.
What Happens After an Aneurysm Is Found
If imaging reveals an aneurysm, the next steps depend entirely on its size and how fast it’s growing. A normal abdominal aorta measures about 2 cm across. An aneurysm is defined as a widening of 50% or more beyond normal, so roughly 3 cm or greater.
Small aneurysms are monitored with periodic imaging rather than treated surgically. U.S. guidelines recommend follow-up intervals based on size: aneurysms between 2.5 and 2.9 cm can be rechecked as infrequently as every five years, while those between 4.5 and 5.4 cm need imaging every six months. The goal is to track the growth rate and intervene before the aneurysm reaches a dangerous diameter.
Surgical repair is generally recommended when an abdominal aneurysm reaches 5.5 cm in men or 5.0 cm in women. For thoracic aneurysms in the ascending aorta, the threshold is also around 5.5 cm at most centers, or 5.0 cm at high-volume centers with specialized aortic teams. Descending thoracic aneurysms have a higher threshold of 6.0 cm. Rapid growth, defined as 0.5 cm or more in a single year, can also trigger surgical referral even if the aneurysm hasn’t hit these size thresholds.
People with genetic connective tissue conditions face lower thresholds. For Marfan syndrome, surgery is considered at 5.0 cm or even 4.5 cm when there’s a family history of dissection. In Loeys-Dietz syndrome, repair may be recommended when the aortic root is just 4.0 cm, because dissections in these patients can occur at diameters that would be considered safe in the general population.