Abdominal Aortic Aneurysm (AAA)

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:

  • Family history of aneurysms (1 in 3 first degree male relatives)
  • Smoking
  • High blood pressure
  • High cholesterol
  • Men with inguinal hernias are 3 times more likely to have an AAA

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:

  • Sudden severe pain in abdomen or back
  • Pain from loin to groin – can mimic renal colic
    • (first episode of renal colic over the age of 55 is a ruptured AAA until proved otherwise)
  • Feeling cold, clammy, sweaty, faint and breathless
  • Hypotensive collapse and loss of consciousness

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.

Red flags
  • AAA more than 5.5cm
  • Known AAA and symptoms suggesting rupture (sudden abdominal/back pain or collapse)
  • First episode of renal colic over the age of 55 is a ruptured AAA unless proved otherwise

Assessment

History and Examination:

Men are at least 6 times more likely than women to develop AAA.

The main risk factors are:

  • Family history of aneurysms (1 in 3 first degree male relatives)
  • Smoking
  • High blood pressure
  • High cholesterol
  • Men with inguinal hernias are 3 times more likely to have an AAA

Signs and Symptoms:

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:

  • Sudden severe pain in abdomen or back
  • Pain from loin to groin – can mimic renal colic
    • (first episode of renal colic over the age of 55 is a ruptured AAA until proved otherwise)
  • Feeling cold, clammy, sweaty, faint and breathless
  • Hypotensive collapse and loss of consciousness

Red Flags

  • AAA more than 5.5cm
  • Known AAA and symptoms suggesting rupture (sudden abdominal/back pain or collapse)
  • First episode of renal colic over the age of 55 is a ruptured AAA until proved otherwise

Investigations

General Practice

Urgent Abdominal Ultrasound (USS) is recommended for any suspicious asymptomatic pulsatile mass found in abdomen during examination

  • The referring clinician will be responsible for reviewing the result and arranging appropriate follow up (see Management and Referral sections)

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
  • All men will receive an automatic invitation in their 65th year to come for initial screening (abdominal USS) which is coordinated by the Screening Programme
  • The Screening Programme cannot screen men less than 65 years in age or women
  • Male patients can contact the screening programme directly to discuss screening if they wish
  • Screening started in 2009 so men born before 1/4/1944 may not have been screened. Patients who have not had AAA screening can self-refer by contacting the programme

Thoracic AA affects men and women equally but is rarer and harder to scan for so there is no screening programme.

Management

Aneurysm Rupture

If an aneurysm ruptures, it will cause internal bleeding. This is a medical emergency. Suggestive symptoms would be:

  • Sudden severe pain in abdomen or back
  • Pain from loin to groin – can mimic renal colic
    • (first episode of renal colic over the age of 55 is a ruptured AAA until proved otherwise)
  • Feeling cold, clammy, sweaty, faint and breathless
  • Hypotensive collapse and loss of consciousness
The NHS AAA Screening Programme

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

  • Patients with a AAA are seen by an AAA nurse. Prescribing and routine observation recommendations will be communicated via letter to GPs e.g. statin, aspirin and regular BP checks – this needs actioning by a GP

Referral

General Practice

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:

  • Small AAA 3-4.4cm should be referred via DRSS as a ROUTINE Vascular referral
  • Medium AAA 4.5-5.4cm should be referred via DRSS as an URGENT Vascular referral. DRSS will email the referral to the Vascular team for rapid assessment and appointment
  • Large AAA more than 5.5 cm should be referred via DRSS as an URGENT Vascular referral. DRSS will email the referral to the Vascular team for very rapid assessment and appointment

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

  • All men will receive an automatic invitation in their 65th year to come for initial screening which is coordinated by the screening programme
  • The screening programme cannot screen men less than 65 years in age or women.
  • Male patients can contact the screening programme directly to discuss screening if they wish
  • Screening started in 2009 so men born before 1/4/1944 may not have been screened. Patients who have not had AAA screening can self-refer by contacting the programme

Referral Instructions

e-Referral Service Selection:

  • Specialty: Surgery - Vascular
  • Clinic Type: Arterial
  • Service: DRSS-Western-Surgery Vascular- Devon CCG 15N

Supporting Information

Patient information

NHS website

Pathway Group

This guideline has been signed off by NHS Devon CCG.

Publication date: October 2019

 

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