Makindo Medical Notes

Related Subjects: Renal Colic | Acute Cholecystitis | Acute Appendicitis | Chronic Peritonitis | Abdominal Aortic Aneurysm | Ectopic Pregnancy | Acute Cholangitis | Acute Abdominal Pain/Peritonitis | Assessing Abdominal Pain | Penetrating Abdominal Trauma

Abdominal Aortic Aneurysms greater than 5.5 cm require surgical repair. The mortality risk is 6% for elective surgery and 50% for emergency surgery. AAA is common in individuals over 60 and should be considered in any presentation of back or abdominal pain.

High Suspicion of AAA Rupture: Management is Emergent and Surgical

Consider CT/USS for high suspicion of AAA rupture Perform ABC, give O₂ if hypoxic, conduct imaging, and contact vascular surgeons/arrange transfer Insert two large-bore cannulas and cross-match. Administer IV fluids. Request 10 units RBC, FFP, and platelets Stop and reverse anticoagulants Maintain BP below MAP 65 mmHg or SBP 90-120 mmHg Inform the operating room, anaesthetist, and vascular surgeons

About AAA

• An aneurysm is a 50% (x1.5) increase in blood vessel diameter
• An abdominal aorta becomes aneurysmal at 3 cm
• Aneurysms larger than 5.5 cm require surgical assessment
• Most AAAs begin below the renal arteries and may extend to the iliac arteries

Aetiology

• Chronic inflammatory process with loss of smooth muscle
• Possible genetic predisposition leading to weakened vessel walls
• Reduction in elastin and collagen contributes to the condition
• Aneurysms can be fusiform or saccular in shape
• As the aneurysm grows, wall tension increases, raising the risk of rupture
• The retroperitoneum may tamponade a bleed, but excessive fluids can raise BP or dilute clotting factors, worsening the bleed

Risk Factors

• Smoking (current or past), increasing age, male (5-10x higher risk), COPD
• Increased height, high BMI
• Connective tissue disorders
• Family history
• Risk factors for rupture: female (3x higher risk), smoking, low FEV1

Clinical Presentation

• Sudden onset of abdominal pain and hypotension
• Pulsatile, expansile mass indicates a leaking AAA
• Gastrointestinal bleeds can occur with aorto-enteral fistulas
• Leaking AAA is a surgical emergency
• Tender abdominal mass suggests a symptomatic aneurysm
• Typically presents in elderly males with severe back or abdominal pain radiating to the groin
• Small bleeds can cause abdominal/back pain and hypotension
• Distal clot embolization can cause limb ischaemia

Investigations

• Lab tests: FBC, U&E, LFTs, lactate, crossmatch, ABG if needed
• Imaging: CXR, ECG, ABG depending on urgency
• Emergency ultrasound: Useful if the aorta is visible. If normal, a leaking AAA is unlikely. If diameter >6 cm, a leak is possible.
• CT Aortogram: Ideal for planning surgery and determining eligibility for emergency EVAR or open surgery. However, delays can be fatal.

Differentials

Differential Diagnosis	Tests	Clinical Features	Management
Appendicitis	Abdominal ultrasound, CT scan, CRP, WBC	RLQ pain, fever, nausea, vomiting	Surgical consultation, antibiotics, appendectomy
Diverticulitis	CT scan with contrast, CRP, WBC	Left lower quadrant pain, fever, bowel changes	Antibiotics, bowel rest, surgery if complicated
Aortic Dissection	CT angiogram, ECG, D-dimer	Ripping chest pain radiating to the back	Blood pressure control, surgery
Incarcerated Hernia	Physical exam, CT scan	Severe abdominal pain, palpable mass	Emergency surgery
Renal Colic	Non-contrast CT scan, urinalysis, renal function tests	Severe flank pain radiating to the groin	Pain control, hydration, possible lithotripsy
Perforation	Abdominal X-ray, CT scan, WBC, CRP	Severe abdominal pain, signs of peritonitis, fever	Emergency surgery, antibiotics, IV fluids
STEMI (ST-Elevation Myocardial Infarction)	ECG, cardiac enzymes (troponins), echocardiogram	Crushing chest pain, radiation to arm/jaw, dyspnea, diaphoresis	Immediate revascularization (PCI or thrombolysis), aspirin, oxygen, nitroglycerin

Emergency Management

• Perform ABC, give oxygen, and administer IV fluids if a leak is suspected. Target SBP: 90-120 mmHg
• IV access: Consider 2 units of O-negative blood. Cross-match for 6-8 units. Contact vascular surgeons for transfer if appropriate. Transfer to a vascular center should occur within 30 minutes of diagnosis
• Most AAAs rupture into the retroperitoneal cavity, causing the classical triad: pain, hypotension, and pulsatile mass. This triad occurs in only 25-50% of cases, leading to frequent misdiagnosis. It is a CEPOD category 1 emergency, requiring immediate intervention. Induction of anesthesia can cause hypotension and should be delayed until surgery is about to start

Open Surgical Repair

• Midline laparotomy or retroperitoneal approach is performed to gain access to the aorta.
• The aneurysm is clamped proximally and distally to the rupture site.
• A synthetic graft (Dacron or PTFE) is sewn into place to replace the damaged section of the aorta.
• Hemodynamic monitoring is crucial throughout the procedure due to the high risk of blood loss and hypotension.
• Postoperative care: Intensive monitoring, fluid resuscitation, and blood transfusions are essential to stabilize the patient postoperatively.

Endovascular Aneurysm Repair (EVAR)

• Less invasive procedure compared to open repair, where a stent graft is inserted via the femoral arteries.
• A catheter is guided to the site of the aneurysm, and the stent graft is deployed to reinforce the aortic wall and prevent further bleeding.
• EVAR is typically performed in cases where patients are hemodynamically stable and fit for this less invasive option.
• Postoperative care: Close imaging follow-up to ensure graft stability and monitor for endoleaks, a common complication of EVAR.

Perioperative Considerations

• Preoperative: Aggressive blood pressure control is necessary, with a target systolic blood pressure of 90-120 mmHg to minimize rupture risk.
• Intraoperative: The patient may require large volumes of blood products (RBCs, FFP, platelets) due to massive blood loss.
• Postoperative: ICU-level care with monitoring for complications such as graft infection, acute kidney injury, or multi-organ failure.

References

• Abdominal Aortic Aneurysm: NICE Guideline
• RCEM Guideline: Ruptured AAA Management

Images Online

• Search for aorta images online