QuestionSBA
QuestionChoice
This is because an abdominal aorta diameter of 3.3cm is considered to be small and so he would be offered annual ultrasound scans in this case. Note that all men in the UK are offered a one-off ultrasound scan at the age of 65 which determines the frequency of scanning if needed. Patients are usually asymptomatic unless the aneurysm has ruptured. Operative management is offered 5.5cm+. AAA's measuring 3-4.4cm are scanned every 12 months, and every 3 months between 4.5-5.4cm.
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12-monthly ultrasound scan
QuestionChoice
This is a common surgical option to repair large or rapidly expanding aneurysms. It involves the insertion of a stent within the abdominal aorta. However, this is not required for this patient as the AAA is only 3.3cm. The indication for repair is when the aneurysm is above 5.5cm or expanding >1cm each year.
53108
b
Endovascular aneurysm repair (EVAR)
QuestionChoice
This is incorrect because ultrasound scanning is only repeated every 3 months or yearly. This would not be an option for this patient.
53111
e
6-monthly ultrasound scan
QuestionChoice
This would be required if the aneurysm is of medium size, between 4.5 to 5.4cm. However, this is not required for this patient as the AAA is only 3.3cm. The indication for repair is when the aneurysm is above 5.5cm or expanding >1cm each year.
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3-monthly ultrasound scan
QuestionChoice
This would be indicated if the patient presented with a ruptured aneurysm, or as an elective procedure to repair large or rapidly expanding AAAs where anatomical considerations make EVAR's unsuitable. A ruptured AAA presents with shock and abdominal pain radiating to the back/back pain. This patient has no features of a ruptured AAA and he does not require repair at this stage due to the small size of the AAA. Open repair surgery is much more invasive than EVAR procedures, and some patients may not be fit enough for this procedure.
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Open repair
QuestionComment
A different question said if >3cm refer to vascular surgeon within 12 weeks ??
28287
QuestionComment
This patient may have been symptomatic or had a rapidly expanding aneurysm (>1cm per year), in which case guidelines would suggest elective repair
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Axillary Dermis
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Poisoned Lyme 
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# Summary


An abdominal aortic aneurysm (AAA) is a common, potentially life-threatening condition characterised by an abdominal aorta diameter greater than 3cm. It's most frequently located between the renal and inferior mesenteric arteries. Key signs and symptoms include a typically asymptomatic presentation, occasionally manifesting as a pulsatile, expansile abdominal mass. Diagnosis primarily relies on abdominal ultrasound screening, with follow-up frequency varying based on the aneurysm size. Management strategies focus on surgical repair, with indications being a size >5.5cm or rapid expansion, encompassing open repair or Endovascular Aneurysm Repair (EVAR).


# Definition


Abdominal aortic aneurysm (AAA) is a prevalent, potentially lethal condition characterised by an enlargement of the abdominal aorta exceeding a diameter of 3cm. This dilatation affects all three layers of the arterial wall. Many individuals with AAA are asymptomatic and do not cause any problems to the individual. In the absence of repair, a ruptured AAA is generally fatal.


# Epidemiology


Abdominal aortic aneurysm (AAA) predominantly affects older adults, especially those over 65 years of age. At the time of screening at age 95, 0.92% of men undergoing screening are found to have an abdominal aortic aneurysm. It is approximately 4-6 times more prevalent among men than women. An estimated 4-8% of men and 1-2% of women aged over 65 years are affected, but due to the asymptomatic nature of the condition, the actual prevalence may be higher. 

There is a significant geographic and ethnic variation, with higher prevalence reported in Western countries. Lifestyle factors such as smoking and a history of cardiovascular disease increase the risk. 

AAA morbidity and mortality are reducing in the UK due to increasing elective repair of AAA and a reduction in smoking rates. 


# Aetiology


The precise aetiology of AAA is complex and multifactorial, typically involving a combination of genetic, environmental, and lifestyle factors.


Risk factors include:

- Being male
- Age 65 or over
- Smoking 
- Hypertension
- Hypercholesterolaemia 
- Family history of AAA
- Personal history of peripheral arterial disease or myocardial infarction
- COPD
- Connective tissue disorders (i.e. Marfan's) 



# Signs and Symptoms


Most AAAs remain asymptomatic for a long time and are often detected incidentally during radiological investigations for other abdominal or pelvic conditions. 

When symptomatic, the clinical presentation can vary:


- Pulsatile abdominal mass: 
- The most classical finding on physical examination is a pulsatile, expansile abdominal mass. This is typically non-tender unless rupture is imminent.
- Approximately 3 in 5 AAA over 3 cm are palpable.
- This may also be associated with abdominal bruit.

- Abdominal or back pain: 
- Pain is usually a late manifestation, suggesting rapid expansion or impending rupture of the aneurysm. 
- It is typically severe, constant, and localised in the abdomen or lower back, often radiating to the flank or groin.
- There can also be testicular pain if the blood supply to this area is compromised by rupture
- 90% of aortic aneurysms are infrarenal (originating below the renal arteries) 


In advanced cases, a large aneurysm may cause symptoms due to compression or displacement of adjacent structures, resulting in early satiety, nausea, weight loss, altered bowel habits, or deep venous thrombosis (due to compression of the inferior vena cava).


# Differential Diagnosis


Differential diagnoses for AAA include, but are not limited to:


- **Renal colic**: Typically presents with severe, sudden onset flank pain that can radiate to the groin, accompanied by haematuria and urinary urgency.
- **Pancreatitis**: Characterised by persistent, severe epigastric pain radiating to the back, often associated with nausea, vomiting, and elevated pancreatic enzymes.
- **Peptic ulcer disease**: Often presents with burning epigastric pain that is relieved by eating, weight loss, and potential signs of bleeding like melaena or hematemesis.
- **Diverticulitis**: Usually presents with left lower quadrant pain, fever, and changes in bowel habits.



# Investigations

NHS AAA screening programme: 

- Offered to men at age 65
- Consists of an abdominal ultrasound
- Follow-up screening depends on the size of the aneurysm:

- Small AAA (3-4.4cm): Yearly repeat ultrasound is offered.
- Medium AAA (4.5-5.4cm): Repeat ultrasound every 3 months is offered.
- Large AAA (>5.5cm): Surgical intervention is generally recommended.

Once an abdominal aortic aneurysm has been detected, further investigations may be required, including: 

- **Computed Tomography (CT) Angiography:** 
- CT angiography is the imaging modality of choice for preoperative evaluation, determining the size, shape, and extent of the AAA, and planning the surgical approach. 
- It provides detailed information about the aneurysm's relationship to branch arteries and the potential presence of thrombus or calcification within the aneurysm. 
- It is also the preferred imaging modality in suspected rupture cases due to its rapid acquisition time and high sensitivity and specificity.

- **Magnetic Resonance Angiography (MRA):** MRA is an alternative to CT angiography for patients who cannot be exposed to ionizing radiation or iodinated contrast medium. MRA can provide high-resolution images of the AAA and surrounding structures but is less readily available and takes more time than CT.

- **Blood tests:** While there is no specific blood test to diagnose AAA, complete blood count, coagulation profile, renal function tests, and electrolyte levels are typically evaluated prior to surgery.



Finally, regular surveillance of known AAAs is critical. The frequency of surveillance depends on the size of the aneurysm, with smaller aneurysms monitored less frequently and larger ones requiring closer observation.


# Management

### Conservative 

Management of abdominal aortic aneurysms may be through conservative measures such as: 

- Surveillance:
- This is typically offered for smaller aneurysms with a lower risk of rupture. It is very rare for smaller AAA to rupture. 
- Small AAA (3-4.4cm): Yearly repeat ultrasound is offered.
- Medium AAA (4.5-5.4cm): Repeat ultrasound every 3 months is offered.
- Large AAA (>5.5cm) require referral to vascular surgery to be seen within 2 weeks of diagnosis. 
- Measures to reduce the risk of rupture:
- Referral to a stop-smoking service
- Management of hypertension 


### Surgical 


Elective repair of AAA may be considered for individuals with AAA who meet the following criteria:

- They are symptomatic 
- Their AAA has grown by more than 1 cm in 1 year and is larger than 4 cm
- Their AAA is 5.5 cm or larger 


Two primary surgical options are available for managing AAA: 

- Open surgical repair
- Typically best for men under age 70. 
- However, it can be contraindicated by anaesthetic risks, medical comorbidities or anatomic difficulties (i.e. horseshoe kidney, stoma, numerous previous surgeries resulting in significant adhesions)
- Endovascular Aneurysm Repair (EVAR)
- A stent graft is inserted through the femoral arteries into the aorta, where it channels blood flow into the iliac arteries. The surrounding aneurysm then becomes thrombosed around the graft. 
- EVAR has reduced perioperative deaths and is associated with shorter hospital stays. However, it has an overall higher long-term morbidity and mortality than open repair. 


# Complications


### Rupture

AAA rupture is a surgical emergency. Abdominal aortic aneurysms are more likely to rupture in women than men but are more common in men and such account for more presentations in men. 

AAA tend to enlarge over time and with increasing size, the risk of rupture increases. 


### Embolization

Rarely distal embolisation from mural thrombus can lead to symptoms related to ischemia, most commonly affecting the distal extremities, such as blue toe syndrome.

### Open Repair-Related Complications

Those undergoing open surgical repair of an AAA have risks including:

- Spinal cord ischaemia 
- Anastomotic pseudoaneurysm 
- Graft infection 
- Death (mortality during elective repair is reported to be 5% of men and 7% of women)

### EVAR-Related Complications

Patients who have undergone EVAR may require surveillance for EVAR-related complications. 

- Endoleak
- Defined as the presence of blood flow within the aneurysm sac but outside the EVAR graft
- Contrast-enhanced CT angiography, or contrast-enhanced ultrasound if CT is contraindicated, is used to assess for endoleak. 
- They can be repaired using open, endovascular or percutaneous intervention for endoleak 
- Post-implantation syndrome 
- Cytokine release due to EVAR can cause fever, back pain and feeling generally unwell following EVAR.

# Prognosis 

Abdominal aortic aneurysms will continue to increase in diameter, with the ultimate outcome being rupture. However, many individuals with AAA do not rupture during their lifetimes. The rupture of AAA is fatal for many individuals. 

For those who have had their AAA electively repaired before rupture, those who have had an open surgical repair tend to fare better with reduced complications and overall improved survival. 


# NICE Guidelines

[NICE guidelines: Abdominal Aortic Aneurysm](https://www.nice.org.uk/guidance/ng156)


# References

[NHS Abdominal Aortic Aneurysm](https://www.nhs.uk/conditions/abdominal-aortic-aneurysm/) 

[NHS Inform Abdominal Aortic Aneurysm](https://www.nhsinform.scot/illnesses-and-conditions/a-to-z/abdominal-aortic-aneurysm/) 

[Patient Info Abdominal Aortic Aneurysms](https://patient.info/doctor/abdominal-aortic-aneurysms)
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An abdominal aortic aneurysm measuring 3.3cm requires annual ultrasound monitoring due to its small size and low risk of rupture.
A 65-year-old male undergoes an abdominal ultrasound scan as part of screening. His ultrasound report states that his abdominal aorta has a diameter of 3.3cm. He states that he currently has no symptoms, but he has a smoking history of 12 pack years.

Which of the following is the best next step in the management of this patient?
a