QA of the Month: February 2014
Syncope and Abdominal Pain
Congratulations Drs. Caldwell, Ladd, Turchi, and Lippert!
70-year-old female visiting from Ireland, h/o HTN, former smoker, BIBA after a syncopal episode and lower abdominal pain with radiation to the back. BP 62/45, pulse 129. Exam with decreased pulses. Bedside ultrasound was immediately performed and the following was seen:
73-year-old female h/o CVA, afib on Coumadin, hypertenstion, hyperlipidemia, current smoker, presenting with new-onset back and abdominal pain. BP upon arrival in 58/34, pulse 109. Patient pallorous. Bedside ultrasound immediately performed and the following was seen:
A Ruptured AAA code was called in both cases and both patients were taken immediately to the OR. Unfortunately, patient in Case 1 expired during surgery; patient in Case 2 had successful endovascular aneurysm repair (EVAR). This goes to show the high mortality of ruptured AAA, despite the best timeliness of diagnosis.
Here are some tips and tricks about abdominal aortic aneurysms and how to best acquire and interpret your images:
- Abdominal aortic aneurysms are defined as greater than 3 cm in diameter at any point; iliac aneurysms are defined as greater than 1.5 cm in diameter.
- Risk factors include male gender, age, smoking history, and history of hyperlipidemia.
- 9,000 Americans die yearly due to a ruptured AAA.
- Only 50% of patients have the classic triad of hypotension, back pain, and pulsatile abdominal mass.
- 90% of AAAs are infra-renal, so it’s imperative that the distal aorta and iliac arteries are visualized.
- Most AAAs are fusiform (involves all three layers of the wall), but saccular aneurysms exist (only involves the adventitia). Thus, obtaining a longitudinal view of the aorta is integral so as not to miss these types of aneurysms.
- Graded compression is an important concept in abdominal ultrasound imaging; this involves pressing on the patient’s abdomen with the ultrasound probe which will allow the air from the intestines to be pushed aside, thus allowing the sonographer to better visualize the structure of interest. This holds true with aorta imaging, which can be difficult for the novice sonographer.
- A recent meta-analysis published by Rubano, et al. in Academic Emergency Medicine showed that emergency bedside ultrasound is 99% sensitive and 98% specific in diagnosing AAA when compared to a reference standard (CT, MRI, radiology-performed US, autopsy results, exploratory laparotomy).
Take home point: AAA is a life-threatening disease and the timely ability to diagnose a ruptured AAA using bedside ultrasound will save lives! Plus, it’s a quick and simple exam to perform. So make sure to keep AAA at the top of your differential diagnosis for any patient with risk factors presenting to the ED in shock – that’s why the aorta scan is part of the RUSH!
- Josh Ennis, Mansour Jammal, and Laleh Gharahbagian