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An Abdominal Aortic Aneurysm (AAA) is a dilated portion of the aorta within the abdomen which may also involve the iliac arteries. They usually grow slowly 1-2mm per year.
Three quarters of aortic aneurysms occur in the abdomen and affect about 1.5 % of men over 65.
Men are at least 6 times more likely than women to develop AAA.
The main risk factors are:
The majority of AAAs are completely asymptomatic and are detected coincidentally or via screening (see below).
If an aneurysm ruptures, it will cause internal bleeding. This is a medical emergency. Suggestive symptoms would be:
Ruptured aortic aneurysms cause 5,000 deaths in the UK each year. They are most common in men over 65 and are responsible for 1 in 75 deaths of men in this age group.
The NHS AAA screening programme is offered to men from age 65.
Thoracic AA affects men and women equally but is rarer and harder to scan for so there is no screening programme.
Men are at least 6 times more likely than women to develop AAA.
The main risk factors are:
The majority of AAAs are completely asymptomatic and are detected coincidentally or via screening - see below:
If an aneurysm ruptures, it will cause internal bleeding. This is a medical emergency. Suggestive symptoms would be:
Urgent Abdominal Ultrasound (USS) is recommended for any suspicious asymptomatic pulsatile mass found in abdomen during examination
If a patient has a strong family history of AAA they need to be screened 5 years before the age of the affected relative. This is not part of the NHS AAA Screening Programme, so will need to be referred by the patient's GP. A routine referral for an USS would be appropriate, unless an aneurysm is suspected on examination. An Urgent USS is appropriate in this scenario.
Thoracic AA affects men and women equally but is rarer and harder to scan for so there is no screening programme.
If an aneurysm ruptures, it will cause internal bleeding. This is a medical emergency. Suggestive symptoms would be:
Below is an outline of the action taken by the NHS AAA Screening Programme. Please note that this is for information only. Any referrals and follow scans required as a result of the NHS AAA Screening Programme will be actioned by the Screening Programme.
Normal aorta less than 3cm: no recall
Small AAA 3-4.4cm (1% of men screened): annual scan advised
Medium AAA 4.5-5.4cm (0.5% men screened): 3 monthly scans advised
Large AAA more than 5.5cm (0.1% men screened): These patients will be referred URGENTLY to the local vascular service (by the NHS AAA Screening Programme). They should be seen within 2 weeks and treated within 8 weeks, if appropriate, after imaging and work-up.
NOTE
If a diagnosis of a AAA is made in General Practice, and not via the National Screening, then a referral to the Vascular Team should be made by the GP as detailed below:
If a patient has a strong family history of AAA they need to be screened 5 years before the age of the affected relative. This is not part of the NHS AAA Screening Programme, so will need to be referred by the patient's GP. A routine referral for an USS would be appropriate, unless an aneurysm is suspected on examination. An Urgent USS is appropriate in this scenario.
The NHS AAA Screening Programme
e-Referral Service Selection:
MyHealth Patient Information - Abdominal Aortic Aneurysm
This guideline has been signed off by NHS Devon.
Publication date: May 2024