Focused questions for aorta ultrasound the questions

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Focused questions for aorta ultrasound The questions for aorta ultrasound are as follows: 1. Is the abdominal aorta > 3 cm in diameter? 2. Are the iliac arteries > 1.5 cm in diameter? If the answers to these questions are no, then the aorta ultrasound evalu- ation is normal. However, one must be careful to examine the entire length of the abdominal aorta and to evaluate in two planes, as described in this chapter. If the answer to either of these questions is yes, then an aneurysm has been diagnosed, and the physician’s next step depends on the clinical picture of the patient. A vascular surgeon should be called immediately for unstable patients and operative repair expedited. For stable but symptomatic patients, further evaluation with a CT scan can be arranged to better define anatomy and facilitate operative repair. Outpatient referral for vascular surgery evalu- ation can be arranged if the aneurysm is asymptomatic and the diameter is < 5 cm [ 3 –5]. Diagnostic ultrasound 115 Abdominal aorta ultrasound
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Anatomy The normal abdominal aorta ( Figure 5.1 ) has a proximal-to-distal taper, and a loss of that taper with a diameter > 3 cm indicates the presence of an AAA. An iliac diameter > 1.5 cm is indicative of an iliac aneurysm. All measure- ments are from outer wall to outer wall (it is better to overestimate in this case than underestimate!). Significant abdominal aneurysms (i.e., high risk of rupture) are ordinarily ± 5 cm in diameter, with a fusiform shape [ 5 ]. Much research has been done to correlate diameter with risk of rupture: AAAs < 4 cm have a 2% per year risk of rupture, AAAs 4–5 cm have a 3–12% per year risk of rupture, and AAAs > 5 cm have a 25–41% risk of rupture [ 2 ]. Technique Probe selection Using a standard 3.5 MHz transducer, the abdominal aorta can usually be visualized in its entirety – down to the iliacs. A curvilinear-array probe will often give the best penetration, especially in patients with a larger body habitus. Views We recommend that the entire length of the aorta should be imaged in real time for a complete exam. In order to document these findings, it is helpful to specifically image the following five areas: Diaphragm Left gastric a. Splenic a. Superior mesenteric a. Testicular a. (spermatic) or Ovarian a. Interior mesenteric a. Common iliac a. Internal iliac a. External iliac a. Celiac trunk Hepatic a. Renal a. Lumbar a. Median sacral a. Figure 5.1 Normal anatomy of the abdominal aorta. 116 Diagnostic ultrasound Abdominal aorta ultrasound
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1. Transverse view of the proximal aorta 2. Transverse view of the mid aorta 3. Transverse view of the distal aorta 4. Transverse view of the distal aorta showing the bifurcation into both iliac arteries 5. Longitudinal/sagittal view of the aorta The most helpful landmark for aorta scanning is the vertebral body shadow – remember that both the aorta and the vena cava will be just anterior to the vertebrae. The aorta will be a bright white circle filled with black located right on top of the vertebral body. One common mistake is to set the depth on the ultrasound machine too shallow to find the vertebrae. It is recommended
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