Abdominal Aortic Aneurysm
If someone presents with signs and symptoms of renal colic above the age of 40 without previous history of renal stones they have an AAA until proven otherwise
Presents as a triad of :
Abdominal or Back Pain of sudden onset
Collapse or Lightheadedness
Hypotension
- An abnormal blood-filled dilatation of a blood vessel (especially in an artery resulting from disease of the vessel wall).
- An Abdominal Catastrophe with up to 30% misdiagnosed initially.
- Abdominal aorta begins at the level of the aortic hiatus of the diaphragm at T12
- Surface anatomy = Xiphoid sternum (dilated aorta palpable above the umbilicus)
- The dilatation is part of a generalized atherosclerotic process
- An aneurysm is defined as a focal increase in the diameter (normal 2cm) of a vessel to greater than 50% of normal; anything less is considered arteriomegaly.
Risk factors
- Male
- Age (biological age)
- Smoking
- Hypertension
- FHx
- Hypercholesterolaemia
- Peripheral Vascular Disease
- Surprisingly diabetes in protective against AAA
Presentation
Sudden Pain
- Back / Abdomen / Flank
- Inguinal / Testicular
Collapse (Lightheadedness)
Aortocaval fistula
- High output cardiac failure
- Pulmonary oedema (flash)
- Leg congestion and swelling
Examination
- Unwell
- Hypotensive
- Diaphoretic
- SOB
- Abdominal Mass (Pulsatile and Expansile)
Initial Mx
Surgical On-Call when Dx suspected
Aim for Stable HYPOtension in resuscitation’ – Rodgers
Management/Investigations in A&E:
IVC – 14G/16G Cannula
IVF – See above
Bloods – FBC/U&E/Coag/GxCM 6 Units
ECG – MI?, Prognosis
Investigations:
Group Xmatch x6
FBC, U&E, Creat, Coag
ECG
ECG (Hardman Criteria)/AMI
Urinanalysis - UOB negative
U/S Aorta (bedside)
CT Abdomen - Takes only if stable
Differential Diagnosis:
Perforated Viscus
Aortic Dissection
Myocardial Infarction
Ureteric Colic
Neurogenic Back Pain
Mechanical Back Pain
Discitis
Surgical Prognosis Determined by:
Hardman Criteria:
Age - > 76Hb - <9.0 g/dlCreat >190mmol/lHx of LOCIschaemia on ECG |
+3 = 100% Mortality +2 = 72% Mortality +1 = 37% Mortality |
Additional Management:
Urinanalysis - Qualitative Microscopic Haematuria
Urinary Catheter - Monitor Urinary Output
ABG - Acid/Base Status, Lactic Acid (bowel?)
Erect CXR - Free Air?
AXR not useful but may show loss psoas shadow
- Approximately 90% (of AAA) are infrarenal.
- The average increase is 2 mm/yr diameter.
- Usually not repaired until they exceed 4-5 cm.
- Risk of rupture within 5 years is 25% at 5 cm diameter.
- AAA > 5 cm have a 3% risk of rupture over 10 years.
References :
Medline Plus Online Medical Dictionary
Shein, M. and Rogers P. Schein’s Common Sense Emergency Abdominal Surgery 2nd Ed. Springer New York : 2005
Cameron, J Ed. Current Surgical Therapy 8th Ed. Elsevier/Mosby Philadelphia PA : 2001
