Author:
Adam S.Kaye
Carlo L.Rosen
Description
- Focal dilation of the aortic wall with an increase in diameter by at least 50% (>3 cm)
- 95% are infrarenal
- Rapid expansion or rupture causes symptoms
- Rupture can occur into the intraperitoneal or retroperitoneal spaces
- Intraperitoneal rupture is usually immediately fatal (20% of ruptured AAA)
- Average growth rate of 0.2-0.5 cm/yr
- Of ruptures:
- 90% overall mortality
- 80% mortality for patients who reach the hospital
- 50% mortality for patients who undergo emergency repair
- Of patients who have had endovascular aortic aneurysm repair (EVAR), persistent bloodflow into the aneurysm sac can lead to continued aneurysm growth and rupture
Geriatric Considerations |
- Risk increases with advanced age
- Present in:
- 4-8% of all patients older than 65 yr
- 5-10% of men 65-79 yr old
- 12.5% of men 75-84 yr old
- 5.2% of women 75-84 yr old
|
Etiology
- Risk factors are similar to other vascular diseases:
- Male gender
- Age >65 yr
- Family history
- Cigarette smoking
- Atherosclerosis
- HTN
- Diabetes mellitus
- Connective tissue disorders:
- Ehlers-Danlos syndrome
- Marfan syndrome
- Uncommon causes:
- Blunt abdominal trauma
- Congenital aneurysm
- Infections of the aorta
- Mycotic aneurysm secondary to endocarditis
- Rupture risk factors:
- Size (annual rupture rates):
- Aneurysms 5-5.9 cm = 4%
- Aneurysms 6-6.9 cm = 7%
- Aneurysms >7 cm = >20%
- Expansion:
- A small aneurysm that grows >0.5 cm in 6 mo is at high risk for rupture
- Gender:
- For aneurysms 4.0-5.5 cm, women have 4× higher risk of rupture compared to men with similar-sized aneurysms
Signs and Symptoms
History
- Abdominal, back, or flank pain:
- Vague, dull quality
- Constant, throbbing, or colicky
- Acute, severe, constant
- Radiates to chest, thigh, inguinal area, or scrotum
- Flank pain radiating to the groin in 10% of cases
- Lower-extremity pain
- Syncope, near-syncope
- Unruptured are most often asymptomatic
Physical Exam
- Unruptured:
- Abdominal mass or fullness
- Palpable, nontender, pulsatile mass
- Intact femoral pulses
- Ruptured:
- Classic triad (only 1/3 of the cases):
- Pain
- Hypotension
- Pulsatile abdominal mass
- Systemic:
- Hypotension
- Tachycardia
- Evidence of systemic embolization
- Abdomen:
- Pulsatile, tender abdominal mass
- Flank ecchymosis (Grey Turner sign) indicates retroperitoneal bleed
- Only 75% of aneurysms >5 cm are palpable
- Abdominal tenderness
- Abdominal bruit
- GI bleeding
- Extremities:
- Diminished or asymmetric pulses in the lower extremities
- Complications:
- Large emboli: Acute painful lower extremity
- Microemboli: Cool, painful, cyanotic toes (“blue toe syndrome”)
- Aneurysmal thrombosis: Acutely ischemic lower extremity
- Aortoenteric or aortoduodenal fistula: GI bleeding
Essential Workup
- Unstable patients:
- Bedside abdominal US
- Explorative surgery without further ancillary studies
- Stable, symptomatic patients:
Diagnostic Tests & Interpretation
Lab
- Type and cross-match blood
- CBC
- Creatinine
- Urinalysis
- Coagulation studies
Imaging
- Abdominal ultrasound:
- 100% sensitive and 92-99% specific for detecting AAA prior to rupture
- Sensitivity has been reported as low as 10% following rupture
- Ultrasound findings consistent with AAA are enlarged aorta >3 cm or focal dilatation of the aorta
- Aortic thrombus can lead to the appearance of a normal-caliber aorta. Measuring from outside to outside of the aortic wall can prevent undermeasurement
- Ultrasound is very limited in the evaluation of patients who have previously had an EVAR, strongly consider CT imaging and expert consultation
- Abdominal CT scan:
- Contrast is not necessary to make the diagnosis but CT angiogram is required for surgical planning for an endovascular approach
- Will demonstrate both aneurysm and site of rupture (intraperitoneal vs. retroperitoneal)
- Allows more accurate measurement of aortic diameter
Differential Diagnosis
- Other abdominal arterial aneurysms (i.e., iliac or renal)
- Aortic dissection
- Renal colic
- Biliary colic
- Musculoskeletal back pain
- Pancreatitis
- Cholecystitis
- Appendicitis
- Bowel obstruction
- Perforated viscus
- Mesenteric ischemia
- Diverticulitis
- GI hemorrhage
- Aortic thromboembolism
- Myocardial infarction
- Addisonian crisis
- Sepsis
- Spinal cord compression
Prehospital
- Establish 2 large-bore IV lines
- Rapid transport to the nearest facility with surgical backup
- Alert ED staff as soon as possible to prepare the following:
- Operating room
- Universal donor blood
- Surgical consultation
Initial Stabilization/Therapy
- 2 large-bore IV lines
- Cardiac monitor
- Hypotensive resuscitation
ED Treatment/Procedures
For patients suspected of symptomatic AAA:
- Emergent surgical consult and operative intervention
- Laparotomy versus endovascular aortic repair (EVAR) by vascular surgeon
- Diagnostic tests should not delay definitive treatment
Disposition
Admission Criteria
All patients with symptomatic AAA require emergent surgical intervention and admission
Discharge Criteria
Asymptomatic patients only
Follow-up Recommendations
- Close vascular surgery follow-up must be arranged prior to discharge
- Instructions to return immediately for:
- Any pain in the back, abdomen, flank, or lower extremities
- Any dizziness or syncope
- ChaikofEL, DalmanRL, Eskand ariMK, et al. The Society for Vascular Surgery practice guidelines on the care of patients with an abdominal aortic aneurysm . J Vasc Surg. 2018;67:2-77.
- DickF, ErdoesG, OpfermannP, et al. Delayed volume resuscitation during initial management of ruptured abdominal aortic aneurysm . J Vasc Surg. 2013;57(4):943-950.
- IMPROVE trial investigators. Observations from the IMPROVE trial concerning the clinical care of patients with ruptured abdominal aortic aneurysm . Br J Surg. 2014;101(3):216-224.
- KentKC. Abdominal aortic aneurysms . N Engl J Med. 2014;371:2101-2108.
See Also (Topic, Algorithm, Electronic Media Element)