Laboratory Studies
- Hematocrit may be lowered in patients with a ruptured aneurysm.
- Coagulation studies may demonstrate coagulopathy.
- BUN and creatinine levels may be elevated in patients with shock and renal hypoperfusion.
- A blood bank sample should be ordered.
- Creatine kinase (CK) and troponin levels may be measured to assess for myocardial infarction.
Imaging Studies
- CT scanning, MRI, angiography, and transesophageal echocardiography are most often used to assess thoracic aneurysm in the emergent setting. The preferred method of assessment depends on the stability of the patient, the availability of radiographic modalities, and the preference of the surgeon. However, CT scanning is most commonly used in both emergent and outpatient settings to diagnose and follow thoracic aneurysm.
- Chest radiography
- Chest radiography should be obtained in the initial workup of patients with chest discomfort.
- Findings may not demonstrate small aneurysms.
- Findings suggestive of aneurysm include mediastinal widening, blurring of the aortic knob, and tracheal displacement. Pleural effusion is usually associated with aortic dissection rather than with a stable aneurysm.
- An elevated hemidiaphragm may suggest phrenic nerve compression from mass effect, but this finding is exceedingly rare compared with the other findings listed.
- Thoracic CT scanning
- Intravenous contrast-enhanced CT scanning is the procedure of choice for diagnosis.
- Its sensitivity is 96-100%, and its specificity is 99% for detecting aneurysms.
- CT scanning is useful in evaluating aneurysm size, proximal and distal extension, presence or absence of dissection, and in seeking other pathology within the chest.
- Use caution in patients with an allergy to the contrast agent or in those with renal failure.
- Use caution in moving patients who are potentially unstable to the CT scanner.
- Contrast angiography
- Contrast angiography is useful in assessing complex aortic pathology and identifying anatomy of branch vessels.
- Its sensitivity is 85% and its specificity is 95% in detecting aneurysms.
- Aortic dissection may not be detected, especially if thrombosis is present in the false lumen.
- Use caution in patients with an allergy to the contrast agent or in those with renal failure.
- Use caution in moving patients who are potentially unstable to the angiography suite.
- Magnetic resonance angiography
- Magnetic resonance angiography is useful in assessing the aortic anatomy, the size of the aneurysm, the dissection, and the branch vessels.
- Its sensitivity is 100% and its specificity is 100% in detecting aneurysms.
- Magnetic resonance angiography does not require the administration of iodinated radiologic contrast material.
- This study requires longer image acquisition times than other modalities.
- Use caution in moving patients who are potentially unstable to the MRI scanner, where distance from the emergency department is compounded by difficulties in hemodynamic monitoring within the scanner.
- Transesophageal echocardiography
- Transesophageal echocardiography is increasingly used to assess the anatomy of the aorta and its valves and the presence of dissection.
- Its sensitivity is 98% and its specificity is 99% in depicting aneurysms.
- Transesophageal echocardiography may be performed rapidly at the bedside.
- The results are operator dependent.
Other Tests
- ECG
- ECG is useful in evaluating patients with chest discomfort or dyspnea.
- Findings may demonstrate strain or ischemia when a proximal aneurysm distorts the anatomy of the aortic valve or the coronary artery. Myocardial infarction may also be present.
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