How to Check for an Aneurysm: Tests and Symptoms

Checking for an aneurysm depends almost entirely on where in the body it might be and whether it has already caused symptoms. A brain aneurysm that ruptures announces itself with a devastating headache and typically lands you in a CT scanner within minutes. An aortic aneurysm in the abdomen often grows silently for years and is caught by ultrasound or CT, sometimes during a routine screening, sometimes by accident. The tests, the urgency, and even the warning signs differ enough between these two that they are worth walking through separately.

Symptoms That Signal a Ruptured Brain Aneurysm

The hallmark symptom is what doctors call a thunderclap headache: a head pain that hits maximum intensity within seconds. In a study of 60 patients who had a confirmed ruptured brain aneurysm, just over half reported this pattern at the time of rupture.¹ People frequently describe it as the worst headache of their life, and it can be accompanied by nausea, vomiting, a stiff neck, blurred or double vision, sensitivity to light, confusion, or loss of consciousness. Seizures sometimes occur. If blood leaks into the brain tissue rather than just the space around it, there can be weakness on one side of the body or difficulty speaking, symptoms that overlap with a stroke, because in many respects it is one.

A sudden severe headache alone, even without other neurological signs, warrants emergency evaluation. A thunderclap headache has also been documented in patients with an unruptured aneurysm that is expanding rapidly, which can be an urgent warning sign that rupture is imminent.² The bottom line: you do not wait for additional symptoms or see how you feel in an hour. You go to an emergency department.

When a Brain Aneurysm Has Not Ruptured

Most unruptured brain aneurysms produce no symptoms at all. Roughly two-thirds of intracranial aneurysms in the general population are smaller than 5 mm, and at that size they rarely press on anything or bleed.³ When an unruptured aneurysm does cause trouble, it is usually because it has grown large enough to push against a nerve or brain tissue. This can show up as a drooping eyelid, a dilated pupil on one side, pain behind or above the eye, numbness or weakness in the face, or vision changes. These “mass effect” symptoms tend to come on gradually, and they are uncommon enough that a person could easily chalk them up to something less serious. There is no reliable self-check for a brain aneurysm; if you have persistent one-sided eye or face symptoms that you cannot explain, imaging is the way to get an answer.

How Brain Aneurysms Are Found on Imaging

Several imaging tools exist, and the choice depends on whether the situation is an emergency, a screening check, or follow-up of something already known.

Non-contrast CT scan: In an emergency where subarachnoid hemorrhage is suspected, a standard CT of the head is usually the first test. It is fast, widely available, and very good at spotting fresh bleeding. It does not, however, show the aneurysm itself in most cases; it shows the blood that leaked out.
CT angiography (CTA): A contrast dye is injected into a vein, and the CT scanner creates a detailed map of the blood vessels. CTA is the workhorse for identifying the aneurysm’s location, shape, and size once bleeding has been confirmed or when an aneurysm is suspected for other reasons.
Magnetic resonance angiography (MRA): Uses an MRI machine to image blood vessels without ionizing radiation. It is commonly used for screening people at higher risk and for monitoring a known aneurysm over time. Many neuroradiologists favor non-contrast MRA for long-term surveillance because it avoids repeated radiation and dye exposure.⁴
Digital subtraction angiography (DSA): A catheter is threaded through an artery, usually from the groin, up to the blood vessels of the brain, and dye is injected directly. DSA remains the gold standard for visualizing aneurysms in fine detail because its resolution is higher than CTA or MRA. It is more invasive, though, and carries a small risk of stroke, so it is generally reserved for pre-surgical planning or when non-invasive tests leave questions unanswered.

CTA and MRA each have strengths and limitations. In one study comparing both against conventional angiography for certain hard-to-detect distal aneurysms, the combined sensitivity of cross-sectional imaging was only about 46%, though specificity was high at 90%.⁵ That particular study looked at unusual aneurysm types in unusual locations, so the numbers should not be taken as a general accuracy rating for CTA or MRA. For the more typical berry aneurysms at common locations in the brain, both CTA and MRA perform considerably better, especially when aneurysms are 3 mm or larger. Still, very small or oddly positioned aneurysms can be missed, which is why DSA sometimes gets the final word.

The Role of Lumbar Puncture After a Negative CT

If a person arrives in the emergency room with a thunderclap headache and the CT scan looks normal, the classic next step is a lumbar puncture. This involves inserting a needle into the lower back to collect a small sample of cerebrospinal fluid and checking it for blood or its breakdown products. The idea is to catch a small subarachnoid hemorrhage that was too subtle for the CT to pick up.⁶

This approach is debated. Modern CT scanners, especially when performed within six hours of headache onset, are extremely sensitive for subarachnoid blood. Some emergency physicians argue that a normal high-quality CT done early enough may be sufficient on its own. Others point out that the occasional CT-negative bleed does occur and that the consequences of missing it are severe. In a hospital-based series of 30 patients who had a sudden severe headache, a negative CT, but a positive lumbar puncture, aneurysms were still found in some of them, underscoring that the lumbar puncture can catch what CT misses in a small number of cases.⁷ The decision often depends on timing: the later the CT is done relative to the headache, the less reliable a normal result becomes, and the stronger the case for a lumbar puncture.

Symptoms of an Aortic Aneurysm

Aortic aneurysms, whether in the chest or abdomen, tend to be silent. An abdominal aortic aneurysm can grow for years without producing any discomfort. When symptoms do appear, they may include a deep, persistent ache in the belly or lower back, or a pulsing sensation near the navel. Some people notice the pulsing only when lying down. These symptoms are vague enough to be attributed to muscle strain or digestive issues, which is why screening matters so much for people at higher risk.

Rupture of an abdominal aortic aneurysm, by contrast, is dramatic and life-threatening. The classic triad is sudden severe abdominal or back pain, low blood pressure, and a pulsatile mass in the abdomen, but only a fraction of patients have all three. A meta-analysis of diagnostic accuracy in suspected ruptured abdominal aortic aneurysms found that hypotension was present in only about 31% of confirmed cases, and a pulsatile abdominal mass in about 47%.⁸ This means relying on clinical signs alone is unreliable, and imaging is needed quickly.

How Aortic Aneurysms Are Detected

Ultrasound is the primary screening tool for abdominal aortic aneurysms. It is painless, uses no radiation, takes about 10 to 15 minutes, and can measure the aorta’s diameter accurately. In the United States, a one-time screening ultrasound is recommended for men aged 65 to 75 who have ever smoked. A validation study comparing abdominal ultrasound to non-contrast CT found that ultrasound had sensitivity in the range of 57 to 70% and specificity above 99%, while CT performed with sensitivity around 83 to 89% and specificity around 98%.⁹ CT is more sensitive, but for a screening test that needs to be cheap, safe, and widely deployable, ultrasound hits the right balance. Even handheld ultrasound devices have shown they can effectively identify patients with aneurysms confirmed by CT.¹⁰

When an aneurysm is found or rupture is suspected, CT angiography becomes the go-to test. It provides precise measurements, shows the aneurysm’s relationship to nearby arteries, and reveals whether blood is leaking. For thoracic aortic aneurysms, CT and MRI are the primary imaging tools, since ultrasound cannot see the chest aorta well through the ribs and lungs.

Can a Doctor Feel an Aneurysm During a Physical Exam?

For abdominal aortic aneurysms, sometimes. A doctor can press on the abdomen and feel for an abnormally wide, pulsating aorta. But the accuracy varies a lot depending on the aneurysm’s size and the patient’s body. A systematic review found that abdominal palpation had an overall sensitivity of about 68% for detecting an abdominal aortic aneurysm. Sensitivity climbed to roughly 82% for aneurysms 5 cm or larger, but dropped to 61% for those between 3 and 4 cm.¹¹ Patients with a waist circumference under 100 cm were far more likely to have their aneurysm detected by palpation (about 91% sensitivity) compared to those with larger waists (about 53%).

A separate study confirmed that physical examination is of limited value for small aneurysms below 4 cm, but becomes more reliable as size increases, with the negative predictive value exceeding 90% for aneurysms 4 cm or larger.¹² In practical terms, a doctor pressing on your belly can reassure you fairly well that you do not have a large aneurysm, but a normal exam does not rule out a smaller one. For brain aneurysms, there is no equivalent physical exam. You cannot feel or listen for a brain aneurysm from the outside.

Incidental Discovery and What Happens Next

Many brain aneurysms are found by accident, during an MRI or CT done for an unrelated reason like a headache workup, a head injury, or sinus problems. This puts you in the strange position of knowing about something potentially dangerous that was not causing any trouble. The decision about what to do next is genuinely difficult. A meta-analysis found that the incidence of aneurysms in the population is significantly larger than the incidence of aneurysmal subarachnoid hemorrhage, and since most of these aneurysms are small, the risks of preventive treatment may outweigh the risk of rupture.³

Size matters enormously. A study of ruptured brain aneurysms found that the mean diameter ranged from about 5.5 mm to 7 mm depending on location, and a majority of ruptured aneurysms in certain locations were actually smaller than 6 mm.¹³ This complicates the old rule of thumb that only aneurysms above a certain size need treatment. Shape, location, growth over time, family history, and patient age all factor into the decision. The American Heart Association and American Stroke Association have published guidelines to help clinicians navigate these considerations for individual patients.¹⁴

For many people with a small, incidentally discovered aneurysm, the recommendation is surveillance rather than immediate intervention. A survey of neuroradiologists found that about 76% endorsed routine periodic imaging for conservatively managed unruptured aneurysms, with 84% recommending surveillance at least once a year, and roughly 59% favoring indefinite lifelong follow-up.⁴ Non-contrast MRA is the preferred method for this ongoing monitoring. If the aneurysm grows or changes shape, that shifts the balance toward treatment.

Risk Factors That Might Justify Screening

For brain aneurysms, screening is not recommended for the general population. It is typically offered to people with two or more first-degree relatives who have had a brain aneurysm or subarachnoid hemorrhage, or to people with certain genetic conditions like autosomal dominant polycystic kidney disease. Smoking and high blood pressure are well-established modifiable risk factors. A case-control study found that male smokers had a higher prevalence of unruptured intracranial aneurysms than the general population, with larger and more irregular aneurysm shapes that increased rupture risk, suggesting that this group may be a reasonable target for screening.¹⁵

For abdominal aortic aneurysms, the screening criteria are more concrete. Most guidelines recommend a one-time ultrasound for men aged 65 to 75 who have a history of smoking. Women are not routinely screened, though some physicians consider it for women who smoke and have other risk factors. Family history of aortic aneurysm, a history of other aneurysms, and connective tissue disorders also raise the threshold for screening. A pilot study has explored combining precise aortic measurements with clinical factors like smoking status, blood pressure medication use, and cholesterol-lowering medication into a composite rupture risk score, though this kind of tool is not yet in routine clinical use.¹⁶

Peripheral Aneurysms

Aneurysms can also form in arteries of the legs, particularly behind the knee (the popliteal artery). Popliteal aneurysms are the most common peripheral aneurysms, and they present differently from brain or aortic ones. Rather than rupturing catastrophically, they tend to cause problems through blood clots that form inside the bulging wall and then travel downstream, blocking smaller arteries in the lower leg and foot. Symptoms can include sudden pain, coldness, or numbness in the foot, or a more gradual onset of cramping and poor circulation.¹⁷ CT angiography is the usual diagnostic tool, and a doctor may also feel a pulsatile mass behind the knee during an exam. People with one popliteal aneurysm have a higher chance of having one on the other side, and also a meaningful chance of having an abdominal aortic aneurysm, so finding one tends to prompt checking for the others.

Blood-Based Biomarkers on the Horizon

One of the frustrations of aneurysm diagnosis is that it relies entirely on imaging. There is no blood test you can walk into a lab and request. That may eventually change. Researchers have identified small molecules called microRNAs circulating in the blood that appear to differ between people with ruptured brain aneurysms and healthy controls. In one study, fourteen microRNAs were found to be significantly altered in aneurysm patients, and bioinformatic analysis linked them to pathways involved in aneurysm development and rupture.¹⁸ This is early-stage work, and no blood biomarker is close to clinical use for aneurysm screening or diagnosis. But the concept of a simple blood draw flagging people who need imaging is appealing enough that research in this area continues to grow. For now, if you want to check for an aneurysm, imaging remains the only reliable path.

Living with an Aneurysm Diagnosis

Receiving an aneurysm diagnosis when you feel perfectly fine creates a particular kind of psychological burden. You know something could go wrong, but the odds say it probably will not, and the treatment itself carries risk. Decision-making in this situation is genuinely uncertain. Research into how patients and doctors navigate these choices has highlighted that the traditional model, where you simply weigh the natural risk of rupture against the risk of a procedure, may not capture what actually matters to individual patients. An alternative approach suggests comparing expected quality-adjusted life-years under each option, which incorporates how the patient feels about living under surveillance versus undergoing a preventive procedure and its recovery.¹⁹ If you are in this position, it is worth asking your doctor not just about the statistical risk but about what each path looks like day to day, and what kind of follow-up each option involves. There is no universally correct answer; the right choice depends on the aneurysm’s characteristics and on how you weigh the trade-offs.

1
Headache Medicine. Prevalence of thunderclap headache in patients with ruptured intracranial aneurysms: series of 60 cases
2
PubMed. Unruptured cerebral aneurysm producing a thunderclap headache
3
PubMed Central. Prevalence of incidental intracranial findings on magnetic resonance imaging: a systematic review and meta-analysis
4
PubMed Central. Management of Small Unruptured Intracranial Aneurysms: A Survey of Neuroradiologists
5
PubMed Central. Comparing magnetic resonance angiography (MRA) and computed tomography angiography (CTA) with conventional angiography in the detection of distal territory cerebral mycotic and oncotic aneurysms
6
Journal of Medicine, University of Santo Tomas. A Review of the Clinical Significance of Lumbar Puncture in the Diagnostic Approach of Aneurysmal Subarachnoid Hemorrhage (SAH): A Case Report of CT-Negative and Lumbar Puncture–Positive SAH
7
PubMed Central. Chance of aneurysm in patients suspected of SAH who have a ‘negative’ CT scan but a ‘positive’ lumbar puncture
8
PubMed. Accuracy of presenting symptoms, physical examination, and imaging for diagnosis of ruptured abdominal aortic aneurysm: Systematic review and meta-analysis
9
PubMed Central. Abdominal ultrasound-scanning versus non-contrast computed tomography as screening method for abdominal aortic aneurysm – a validation study from the randomized DANCAVAS study
10
The American Journal of Cardiology. Comparison With Computed Tomography of Two Ultrasound Devices for Diagnosis of Abdominal Aortic Aneurysm
11
PubMed. The accuracy of physical examination to detect abdominal aortic aneurysm
12
European Journal of Vascular and Endovascular Surgery. The Value of Abdominal Examination in the Diagnosis of Abdominal Aortic Aneurysm
13
PubMed Central. Size and location of ruptured intracranial aneurysms
14
PubMed. Guidelines for the Management of Patients With Unruptured Intracranial Aneurysms: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association
15
PubMed. Increased prevalence and size of incidental unruptured intracranial aneurysms in male smokers: A case-control study
16
Journal of Vascular Surgery Cases, Innovations and Techniques. An abdominal aortic aneurysm rupture risk score: A pilot study for combining precise aortic measurements and clinical factors
17
Cureus. Open Repair of a Giant Superficial Femoral-Popliteal Artery Aneurysm Using Autologous Saphenous Vein Bypass: A Case Report
18
Stroke. Abstract WMP30: Circulating MicroRNAs as Potential Novel Diagnostic Biomarkers for Ruptured Intracranial Aneurysm
19
Neurochirurgie. Understanding decision making for preventive interventions: The unruptured intracranial aneurysm example