Wiler, Jennifer L. MD, MBA
Dr. Wiler is an assistant professor of emergency medicine and the vice chair of the department of emergency medicine at the University of Colorado School of Medicine. Read her past columns at http://bit.ly/WilerConsult.
An 89-year-old woman presents with a three-day history of lower abdominal and back pain. She said she feels rectal pressure that radiates to both legs. She denies fevers, trauma, syncope, chest pain, constipation, and weakness.
She has been incontinent of urine twice the day before, which is new for her, but denies dysuria, frequency, or saddle anesthesia. Her past medical history is significant for cardiovascular disease and hypertension.
You perform a bedside ultrasound. What is the diagnosis and treatment of this condition?
Diagnosis: Abdominal Aortic Aneurysm
An aneurysm is the segmental dilation of a blood vessel that is 50 percent or greater than normal size. Non-full thickness dilations are known as pseudoaneurysms. The abdominal aorta lies slightly left of midline in the retroperitoneum and extends from the diaphragm hiatus to fourth vertebra and the bifurcation of the iliac arteries. The abdominal aorta is the most common arterial aneurysm, defined as more than or equal to 3.0 cm infrarenally (Circulation 2006;113:e463) and most commonly occurring in the area between the renal and inferior mesenteric arteries.
Many risk factors are associated with developing AAAs, including advancing age, being Caucasian, family history, hypertension, and atherosclerosis, but a personal history of smoking has been noted to have the strongest predilection. (Ann Intern Med 1997;126:441.) Screening for AAAs at least 3 cm in men 65 or older has been shown to decrease AAA rupture and AAA-related mortality. (Ann Intern Med 2014;160:321.) These studies also found that as many as eight percent of older males have an occult AAA. (Br J Surg 1998;85:1090.)
AAAs may present in a variety of ways. They may be asymptomatic and be noted incidentally on physical examination or be an incidental finding on imaging. They may also be symptomatic but unruptured. This is typically related to pain from rapidly expanding size, associated compression of local structures, and ischemia or infarction, or it is related to inflammatory or infectious symptoms. Yet others can present as symptomatic and ruptured. These patients may present with circulatory collapse related to hemorrhage into the retroperitoneal space. The classic presentation is the triad of a pulsatile abdominal mass, hypotension, and severe abdominal pain, but that occurs in less than 50 percent of cases. (Ann Vasc Surg 2010;24:308.)
The definitive diagnostic modality for unruptured aneurysms is ultrasound, though CT is the preferred modality for evaluating suspected ruptured AAAs. (Circulation 2010;122:1880.)
Managing AAA depends on the size of the aneurysm and whether symptoms are present. Treating ruptured AAAs can be performed by an open operative repair technique or endovascularly, depending on institutional resources. ED management should include standard resuscitation for abdominal hemorrhage and emergent consultation with a vascular surgeon. Patients with symptomatic AAAs should be admitted for observation and be considered for operative repair.
Treating symptomatic nonruptured AAAs has changed in the past 15 years. (Eur J Vasc Endovasc Surg 2014 Apr 16.) Previously, the primary treatment option was open endovascular procedure; now many are performed endovascularly, which has allowed patients who were previously not operative candidates to have treatment. (J Vasc Surg 2009;49:543.) Treatment of symptomatic AAAs depends on the size of the aneurysm and the patient's other comorbid conditions. Aneurysms generally grow approximately 0.4 cm per year. (Eur J Vasc Endovasc Surg 2006;31:231.) The annual rate of rupture risk for small to medium aneurysms (diameter <5.5 cm), however, has been found to be similar to the risk of repair. (Lancet 1998;352:1649.) The Society for Vascular Surgery currently recommends surveillance for patients with a fusiform AAA of 4.0 to 5.4 cm. (Adv Surg 2013;47:271.)
This patient was admitted to the hospital and had an endovascular aneurysm repair. She was discharged to a skilled nursing facility without incident.
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