AAA Surveillance — How Often Should an Aneurysm Be Scanned?
Surveillance intervals are set by size, and the NHS runs the programme that does it. Here is how the schedule works and where a private scan sensibly fits.
Sudden severe abdominal or back pain — call 999
Sudden, severe pain in the abdomen or lower back, particularly with feeling faint, collapse, or a pulsating sensation in the abdomen, can indicate a rupturing aneurysm. This is a medical emergency — call 999. Do not drive yourself anywhere and do not wait for a scan appointment.
An abdominal aortic aneurysm is a swelling of the main artery running through the abdomen. Most cause no symptoms at all, which is why they are usually found on screening or by chance during a scan for something else. The risk is rupture, and that risk relates closely to size — which is what surveillance is designed to track.
How surveillance intervals work
| Aorta diameter | Category | Typical NHS approach |
|---|---|---|
| Under 3.0 cm | Normal | No aneurysm — no further surveillance after a normal screening scan |
| 3.0–4.4 cm | Small | Rescanned around every 12 months |
| 4.5–5.4 cm | Medium | Rescanned around every 3 months |
| 5.5 cm or more | Large | Referred to a vascular team to discuss repair |
These are the bands the NHS Abdominal Aortic Aneurysm Screening Programme works to. Rapid growth between scans can shorten an interval regardless of the absolute size, and your own team may adjust the plan for your circumstances — their instructions take precedence over any table on a website.
Who the NHS screens — and who it does not
In England, men are invited for a single screening scan in the year they turn 65. That one scan catches most aneurysms that matter, because they are far more common in men and rarely develop dangerously before that age. Men over 65 who have never been screened can request a scan directly through their local programme — it does not require a GP referral, and it is free.
Women are not routinely screened, since aneurysms are considerably less common in women, and population screening has not been shown to benefit them overall. That does not mean a woman cannot have one — it means the case for scanning is individual rather than automatic, and worth discussing with a GP if you have a strong family history or several risk factors.
Risk rises with age, smoking history, high blood pressure, and having a parent or sibling who had an aneurysm. If that describes you and you are outside the invited group, a conversation with your GP is the right starting point.
Where a private scan fits — and where it does not
If you are already under NHS surveillance, stay in it. The programme tracks your measurements over time, recalls you automatically, and refers you when the threshold is reached. That continuity is the whole value, and a one-off private scan does not replicate it. Measurements taken on different machines by different people also vary slightly, which makes a single outside number harder to compare against your own series.
Where a private scan is genuinely reasonable: you are eligible but have not been screened and want it done sooner; you are outside the invited group with a strong family history and your GP agrees imaging is sensible; you have a known aneurysm and want an additional check between NHS appointments; or an aneurysm was mentioned incidentally on another scan and you want it measured properly.
How the appointment runs
- 1
PreparationDo not eat for four hours beforehand — less bowel gas means a clearer view of the aorta. Water is fine and take your usual medicines. 30 minutes.
- 2
The scanLying on your back with warm gel over the abdomen. The aorta is followed along its length and measured at its widest point.
- 3
What we measureMaximum aortic diameter, the shape and extent of any aneurysm, and the iliac arteries where they can be seen.
- 4
ResultsExplained on screen as we scan, written report usually within two hours — with the measurement stated clearly so your GP or vascular team can place it against your previous scans.
Your questions answered
How often should a small aneurysm be scanned?
At what size is repair considered?
Should women be screened?
Can an aneurysm shrink?
Does an aneurysm cause symptoms?
Why do measurements differ slightly between scans?
Where to go from here
Measured properly, reported clearly
The aorta followed along its length and measured at its widest point in a 30-minute appointment — explained on screen as we scan, with the written report usually within two hours for your GP or vascular team.
Kensington, London W8 4ED
3 mins from Notting Hill Gate
This article is general information about aortic aneurysm surveillance, not individual medical advice. Sudden severe abdominal or back pain with faintness is a 999 emergency. If you are already under NHS surveillance, follow your programme’s schedule — see NHS guidance on abdominal aortic aneurysm and the AAA screening programme.
Written and clinically reviewed by the HCPC-registered sonographers who perform this scan at IUS London — a CQC-registered diagnostic ultrasound clinic (Provider ID 1-2775844974). Your own findings are explained to you at the scan and set out in your report.
Author: Yianni Kiromitis, Senior Sonographer, HCPC RA38415 — over 20 years’ experience in NHS and private ultrasound
Medically reviewed: 9 August 2026
