Abdominal Aorta Ultrasonography (Abdominal Aorta Echogram, Abdominal Aorta Ultrasound)
Norm of Abdominal Aorta Ultrasonography (Abdominal Aorta Echogram, Abdominal Aorta Ultrasound)
Negative for presence of aneurysm. Normal cross-sectional diameter of adult aorta (maximum internal diameter) varies from 3 cm at the xiphoid to about 1 cm at the bifurcation. Transverse and vertical diameters should be the same. Measurements should be taken at various points down the length of the aorta. Any significant increase in diameter toward the feet (caudally) is abnormal. Ultrasound underestimates the anteroposterior diameter (mean, 2.16 mm) and transverse diameter (mean, 4.29 mm) of the abdominal aorta.
Usage of Abdominal Aorta Ultrasonography (Abdominal Aorta Echogram, Abdominal Aorta Ultrasound)
Localization, measurement, and monitoring of abdominal aortic aneurysm; follow-up evaluation of surgical graft and aortic attachment after surgery for aneurysm; and detection of abdominal aortic atherosclerosis or thrombus. May be indicated in clients with pulsatile abdominal mass, poor circulation of the legs, recent abdominal trauma, and suspected idiopathic aortitis.
Description of Abdominal Aorta Ultrasonography (Abdominal Aorta Echogram, Abdominal Aorta Ultrasound)
Evaluation of the structure, size, and position of the abdominal aorta and branches (celiac trunk and renal, superior mesenteric, and common iliac arteries) by the creation of an oscilloscopic picture from the echoes of high-frequency sound waves passing over the anterior portion of the trunk (acoustic imaging). The time required for the ultrasonic beam to be reflected back to the transducer from differing densities of tissue is converted by a computer to an electrical impulse displayed on an oscilloscopic screen to create a three-dimensional picture of the abdominal aorta and branches. Ultrasonography allows measurement of the luminal diameter of the aorta. A narrowed lumen would indicate atherosclerosis or thrombus, whereas a wider-than-normal lumen with an irregular border may indicate aneurysm. Scattered internal echoes within the aneurysm may indicate an internal clot. A double lumen may indicate a tear in the wall of the abdominal aorta. Surgical grafts from aneurysm repair appear as bright echo reflections.
Professional Considerations of Abdominal Aorta Ultrasonography (Abdominal Aorta Echogram, Abdominal Aorta Ultrasound)
Consent form NOT required.
- This test should be performed before intestinal barium tests or else after the barium is cleared from the system (with allowance of several days for clearance).
- An enema may be prescribed to be given before the ultrasonogram is taken.
- The client should wear a gown.
- Obtain ultrasonic gel or paste.
- Client is positioned supine on a procedure table.
- The abdomen is covered with conductive gel.
- A lubricated transducer is passed slowly along the abdomen at 1-cm intervals along the transverse and then longitudinal lines, covering the area between the xiphoid process and the symphysis pubis. If dissection is suspected, real-time techniques can be used more specifically to locate the site.
- Photographs are taken of the oscilloscopic images.
- Procedure takes less than 60 minutes.
- Cleanse skin of ultrasonic gel.
Client and Family Teaching
- Eat a low-residue diet the day before the ultrasonogram is taken, fast from food and fluids after midnight before the test, and refrain from smoking.
- Lie as still as possible during the procedure, which is painless and carries no risks.
- Results are normally available within 24 hours.
Factors That Affect Results
- Dehydration interferes with adequate contrast between organs and body fluids.
- Intestinal barium or gas obscures results by preventing proper transmission and deflection of the high-frequency sound waves.
- The more abdominal fat present, the greater is the attenuation (reduction in sound-wave amplitude and intensity), which interferes with the clarity of the picture.
- Aorta may be displaced by scoliosis, a retroperitoneal mass, or the para-aortic lymph nodes; in some clients, these anomalies can mimic an aneurysm.
- There is some evidence that aneurysms smaller than 4 cm in diameter may be safely followed by ongoing monitoring and any aneurysm larger than 4 cm in diameter should be considered for surgery.
- Ultrasound ranks below CAT scan (or CT scan) in its accuracy; however, it surpasses CT in screening.