04-27-2008, 07:18 AM
Initial test of choice for asymptomatic Abdominal aortic aneurysm?
Ultrasound or CT Scan
Ultrasound or CT Scan
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Initial test for AAA? - mirt
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04-27-2008, 07:37 AM
thnx guys.................But crush step 3 says CT scan............page 84
04-27-2008, 07:47 AM
I know Crush says CT
Now see what CMDT 2008 says: Abdominal Aortic Aneurysms Essentials of Diagnosis Most aortic aneurysms are asymptomatic until rupture. Abdominal aortic aneurysms measuring 5 cm are palpable in 80% of patients. Back or abdominal pain with aneurysmal tenderness may precede rupture. Rupture is catastrophic; hypotension; excruciating abdominal pain that radiates the back. General Considerations Dilatation of the infrarenal aorta is a normal part of aging. The aorta of a healthy young man measures approximately 2 cm. An aneurysm is considered present when the aortic diameter exceeds 3 cm, but aneurysms rarely cause any problems until their diameter exceeds 5 cm. Abdominal aortic aneurysms are found in 2% of men over 55 years of age; the male to female ratio is 8:1. Ninety percent of abdominal atherosclerotic aneurysms originate below the renal arteries. The aneurysms usually involve the aortic bifurcation and often involve the common iliac arteries. Inflammatory aneurysms happen when an inflammatory peel, similar to the inflammation that occurs with retroperitoneal fibrosis, surrounds the aneurysm and encases the retroperitoneal structures, which include the duodenum and, occasionally, the ureters (see photograph). Clinical Findings Symptoms and Signs Asymptomatic Although 80% of 5-cm infrarenal aneurysms are palpable on routine physical examination, most aneurysms are discovered as incidental findings on ultrasound or CT imaging during the evaluation of unrelated abdominal symptoms. Symptomatic Pain Aneurysmal expansion may be accompanied by pain that is mild to severe midabdominal discomfort often radiating to the lower back. The pain may be constant or intermittent and is exacerbated by even gentle pressure on the aneurysm sack. The pain may also accompany inflammatory aneurysms. Rupture The sudden escape of blood into the retroperitoneal space causes severe pain, a palpable abdominal mass, and hypotension. Free rupture into the peritoneal cavity is a lethal event. Most aneurysms have a thick lining of blood clot, which can break away, float with the blood to a small peripheral artery where it occludes blood flow (embolism). Although this phenomenon is rare, multiple localized areas of poor peripheral blood flow (blue toe syndrome), should prompt a search for an aneurysm. Laboratory Findings Even with a contained rupture, there may be little change in routine laboratory findings. The hematocrit will be normal, since there has been no opportunity for hemodilution. Aneurysms are associated with the cardiopulmonary diseases of elderly male smokers, which include coronary artery disease, carotid disease, renal impairment, and emphysema. Preoperative testing may indicate the presence of these comorbid conditions. Imaging Abdominal ultrasonography is the diagnostic study of choice for initial diagnosis (see ultrasound). In approximately three-quarters of patients with aneurysms, curvilinear calcifications outlining portions of the aneurysm wall may be visible on plain films of the abdomen or back. CT scans provide a more reliable assessment of aneurysm diameter and should be done when the aneurysm nears the diameter threshold for treatment. Contrast-enhanced CT scans show the arteries above and below the aneurysm (see CT Scan). The visualization of this vasculature is essential for planning repair. Screening There are now data to support using abdominal ultrasound to screen 65- to 74-year-old men, but not women, who have a history of smoking. Repeated screening does not appear to be needed. Treatment Aneurysmal Rupture If the rupture and bleeding are confined to the retroperitoneum, the combination of low blood pressure and retroperitoneal containment may arrest the blood loss long enough for the patient to undergo urgent operation. Endovascular repair represents the best opportunity for survival because the retroperitoneal blood clot is left intact. Patients who have free rupture of the aneurysm into the peritoneum do not survive long enough to undergo surgical repair. Elective Repair In general, elective repair is indicated for aortic aneurysms > 5.5 cm in diameter or aneurysms that have undergone rapid expansion (> 5 mm in 6 months). Symptoms such as pain or tenderness may indicate impending rupture. These patients need to undergo aneurysm repair regardless of the aneurysm's diameter. Improving outcomes with endovascular techniques have caused some experts to recommend treatment of smaller aneurysms. Current studies are ongoing to determine whether this may be appropriate. |
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