Abdominal Aortic Aneurysm (AAA)

Background Knowledge 🧠

Definition

An abdominal aortic aneurysm (AAA) is a permanent pathological dilation of the abdominal aorta with a diameter over 1.5 times the expected anteroposterior diameter of that segment, given the person’s sex and body size.

Normally the diameter of the abdominal aorta ranges from 1.2–2.4 cm.
The threshold for diagnosis of AAA is an abdominal aortic diameter of 3.0 cm or greater.

Epidemiology

More common in males and those over the age of 65.

Associated with other vascular aneurysms, particularly popliteal artery aneurysms.

Risk Factors

Smoking: Single most important risk factor.

Age

Family history of AAA

Hypertension

Hypercholesterolaemia

Atherosclerosis

Pathophysiology

Debate on the exact cause but atherosclerosis is considered a major contributor.

Inflammatory processes weaken the aortic wall, leading to dilatation.

Clinical Features 🌡️

Clinical Presentation

Most are asymptomatic and found incidentally on imaging or examination.

Symptoms, if present, include:
- Abdominal pain or back pain.

- Pulsatile mass in the abdomen.

If ruptured:
- Severe abdominal pain
- Shock
- Collapse

Investigations 🧪

Investigations

Abdominal ultrasound: First-line investigation and used for screening.

CT angiography: Provides detailed imaging, particularly if surgery is being considered.

Management 🥼

Management

Small AAAs (<5.5cm in men, <5cm in women):
- Managed conservatively with regular monitoring and ultrasound scans.

Larger or rapidly expanding AAAs:
- May require surgical intervention either by open repair or endovascular aneurysm repair (EVAR).

Other management considerations:
- Optimise blood pressure control.
- Stop smoking.
- Statins and aspirin if indicated.

Complications

Rupture: Life-threatening emergency with high mortality.

Thrombosis or embolisation from the aneurysm.

Prognosis

With early detection and appropriate management, prognosis can be good.

Ruptured AAA has a high mortality rate, with many patients dying before reaching the hospital.

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💡 We've found 5 questions

Average

Platform average

28826

Regarding abdominal aortic aneurysms:

31542

Regarding abdominal aortic aneurysms:

A computed tomography (CT) scan is an essential pre-operative investigation if rupture is suspected

Urgent laparotomy is mandatory to avoid unnecessary delay, if there is a high clinical suspicion of rupture.

They affect males and females equally

They are more common in males

Repair is generally considered once the diameter has exceeded 3.5 cm

5.5 cm is the commonly quoted threshold.

Trash foot is a complication of surgery

Embolization of the aneurysm can occlude the small vessels of the feet, leading to areas of necrosis.

Repair is not possible if the patient is unable to tolerate a laparotomy

Endovascular repair is another option

AI Feedback

11.76% of users got this question correct

Answer Explanation:

The correct answer is ‘Trash foot is a complication of surgery’. This is because trash foot, also known as embolic gangrene, is a known complication of abdominal aortic aneurysm (AAA) repair. It occurs when small emboli break off from the aneurysm or graft and occlude the small vessels of the foot, leading to tissue necrosis.

Incorrect Options Explanation:

‘A computed tomography (CT) scan is an essential pre-operative investigation if rupture is suspected’ – While a CT scan is indeed an important investigation in the diagnosis and management of AAA, it is not necessarily ‘essential’ if rupture is suspected. In such a case, the patient’s hemodynamic status is the most important factor and immediate surgery may be required.
‘They affect males and females equally’ – This is incorrect. AAA is more common in males than in females.
‘Repair is generally considered once the diameter has exceeded 3.5 cm’ – This is incorrect. The threshold for surgical intervention is generally considered to be a diameter of 5.5 cm or more, or rapid expansion of the aneurysm.
‘Repair is not possible if the patient is unable to tolerate a laparotomy’ – This is incorrect. Endovascular aneurysm repair (EVAR) is a less invasive option that can be considered in patients who are unfit for open surgery.

Overview of Abdominal Aortic Aneurysms:

Definition: An abdominal aortic aneurysm (AAA) is a localized enlargement of the abdominal aorta that exceeds the normal diameter by more than 50 percent.
Epidemiology: AAA is more common in males and in individuals over the age of 65. Risk factors include smoking, hypertension, and a family history of AAA.
Clinical Presentation: Most AAAs are asymptomatic and are discovered incidentally. Symptoms, when present, may include abdominal or back pain. A pulsatile abdominal mass may be palpable on physical examination.
Complications: The most serious complication of AAA is rupture, which can lead to life-threatening internal bleeding. Other complications include thrombosis and embolization, leading to ischemia of the lower limbs (‘trash foot’).
Management: Small AAAs (less than 5.5 cm in diameter) are usually managed conservatively with regular monitoring and control of cardiovascular risk factors. Surgical repair, either by open surgery or endovascular intervention, is indicated for larger aneurysms or those that are rapidly expanding.

33518

A 68-year-old man presents with renal colic. On reporting a CT of his renal tract, the radiologist notes the presence of a 5 cm infrarenal aortic aneurysm. What is the most appropriate management plan for this incidental finding?

33516

A 72-year-old man attends outpatients for his regular abdominal aortic ultrasound. On this occasion, his aortic diameter is 5.9 cm. This compares with 4.2 cm 6 months previously. What is the most appropriate management plan?

33515

A 62-year-old man presents with renal colic. On reporting a CT of his renal tract, the radiologist notes the presence of a 3 cm infrarenal aortic aneurysm. What is the most appropriate management plan for this incidental finding?

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