Review Question - QID 103297

This elderly patient with a 50 pack year smoking history, sudden onset abdominal pain, and hemodynamic instability likely has a ruptured abdominal aortic aneurysm (AAA). The most appropriate initial step in management is bedside abdominal ultrasound

A AAA is a local enlargement of the abdominal aorta >3 cm that is commonly observed in elderly patients. Risk factors include smoking, high blood pressure, atherosclerotic disease, and connective tissue disorders. Smoking is the most common and strongest single risk factor. AAA rupture is a true emergency with mortality exceeding 90%. Symptoms include vague back, abdominal, or chest pain and are often accompanied by hypotension and hemodynamic instability. When rupture occurs, blood may accumulate in the peritoneum or retroperitoneal space depending on the location of the aortic wall defect. In cases of retroperitoneal rupture, flank ecchymosis (Grey Turner's sign) may be observed (Figure A). For hemodynamically stable patients with suspected AAA rupture, the initial diagnostic step is a CT scan of the abdomen with contrast. For patients with hemodynamic instability, however, point of care ultrasound of the abdomen is the initial step in management.

Upchurch and Schaub review the diagnosis and management of AAA rupture. They state symptomatic aneurysms present with back, abdominal, buttock, groin, testicular, or leg pain and require urgent surgical attention. Rupture of an AAA involves complete loss of aortic wall integrity and is a surgical emergency requiring immediate repair. The mortality rate approaches 90 percent if rupture occurs outside the hospital.

Lyon and Clark review the diagnosis of acute abdominal pain in older patients. They state acute abdominal pain is a common presenting complaint in older patients. Presentation may differ from that of the younger patient and is often complicated by coexistent disease, delays in presentation, and physical and social barriers. The physical examination can be misleadingly benign, even with catastrophic conditions such as abdominal aortic aneurysm rupture and mesenteric ischemia.

Figure A demonstrates flank ecchymosis or Grey Turner's sign which can be observed in retroperitoneal bleeds such as AAA rupture.
Figure B demonstrates an EKG with normal sinus rhythm.

Illustration A demonstrates periumbilical ecchymosis or Cullen's sign which can also be observed in AAA rupture.
Illustration B is an abdominal ultrasound demonstrating a ruptured AAA. Illustration C is a contrast enhanced abdominal CT demonstrating a ruptured AAA.

Incorrect Answers:
Answer 2: Chest radiograph may be useful for detecting a widened mediastinum in patients with suspected thoracic aortic dissection. However, this patient's presentation is more suggestive of AAA.

Answer 3: CT angiography of the abdomen is the initial diagnostic step for patients with suspected AAA rupture that are hemodynamically stable. This patient's vital signs indicate hemodynamic instability and warrant a bedside abdominal ultrasound.

Answer 4: Serum lipase would be appropriate for suspected pancreatitis, which may also rarely present with Grey Turner's sign. However, this patients presentation is more suggestive of ruptured AAA.

Answer 5: Serum troponin would be appropriate for patients with suspected myocardial infarction, which may present with epigastric abdominal pain in some patients. However, this patients presentation is more suggestive of ruptured AAA.

Bullet Summary:
For patient's with suspected rupture of an abdominal aortic aneurysm that are hemodynamically unstable, the initial diagnostic step is an abdominal ultrasound.