View source for Aortic ultrasound

==Background==
[[File:Aorta segments.jpg|thumb|Schematic view of the aorta and its segments.]]
*Aortic ultrasound should be utilized to assess for aneurysm or dissection
*Aneurysm is defined as 3cm (150% the upper limit of normal) at the level of the renal arteries (L1-2 vertebral body level)
*Risk of [[AAA]] rupture significantly increases at 5cm but should be ruled out in the proper clinical setting when >3cm
*AAA’s are most commonly infrarenal
*EM providers have an accuracy of 100% in assessing for AAA<ref>Kuhn M, Bonnin RL, Davey MJ, Rowland JL, et al. Emergency department ultrasound scanning for abdominal aortic aneurysm: accessible, accurate, and advantageous. Ann Emerg Med. 2000; 36(3):219-223.</ref>
*An intimal flap is 67–80% sensitive and 99–100% specific for dissection<ref>Fojtik JP, Costantino TG, Dean AJ. The diagnosis of aortic dissection by emergency medicine ultrasound. J Emerg Med. 2007; 32(2):191-196.</ref>

==Indications==
*Classic triad for [[AAA]] is pain, hypotension, and pulsatile mass

==Technique==
===5-Point Assessment===
#Select probe
#*Curvilinear/large convex probe (phased array probe may substitute)
#Location
#*Start at the superior aspect of the abdomen below the xyphoid process
#*Visualize aorta on the patient’s left, IVC on the right, and vertebral shadow posteriorly
#Transverse views
##Proximal aorta
##Mid-aorta
##Distal aorta
##Aortic bifurcation
#Longitudinal view
##Distal aorta (to assess for saccular aneurysms)

==Findings==
*AAA identified when diameter measured from outer wall to outer wall (including mural thrombus if present) is >3cm
*Iliac vessels at bifurcation, outer wall to outer wall <1.5 cm<ref>Tayal VS, et al. Acad Emerg Med, 2003. PMID 12896888</ref>
*Abdominal aortic dissection can be identified as an intimal flap

==Images==
===Normal===
[[File:Normal Aorta.JPG|200px]]

===Abnormal===
====[[Abdominal Aortic Aneurysm]]====
[[File:AAA.png|200px]]
[[File:AAA2.png|200px]]

====[[Aortic Dissection]]====
 [[File:Type B Dissection.png|350px]]

==Pearls and Pitfalls==
*Measurements should be done in a transverse view of the aorta for best wall to wall measurement
**Avoid oblique measurements which can be falsely large
*IVC can be differentiated by aorta as it is on the patient’s right, thin-walled, nonpulsatile, and compressible (depending on habitus)
*Constant gentle pressure and jiggling the probe can help to move bowel gas to visualize the aorta
*In the setting of ruptured AAA, blood may not show up in a fast exam if the bleeding is retroperitoneal
*AAA vs Dissection
**Dissections will continue while AAA typically are located in single area
**Dissections can be a normal diameter
*Mural thrombus can cause falsely small measurements
*Utrasound generally cannot differentiate ruptured from an intact AAA. The distinction is made based on clinical context.

==Documentation==
===Normal Exam===
A bedside ultrasound was conducted to assess for AAA with clinical indications of hypotension and lower back pain. The aorta was assessed at 4 locations in the transverse plane – proximal, mid, distal, and aortic bifurcation. Additionally, the distal aorta was viewed in the sagittal plane. No sonographic evidence of AAA at these sites.

===Abnormal Exam===
A bedside ultrasound was conducted to assess for AAA with clinical indications of hypotension and lower back pain. The aorta was assessed at 4 locations in the transverse plane – proximal, mid, distal, and aortic bifurcation. Additionally, the distal aorta was viewed in the sagittal plane. A 5.5cm AAA was discovered in the distal aorta.

==Clips==
[[File:Celiac and SMA.gif|Celiac and SMA identified]]
[[File:Normal aortic bifurcation.gif|Aortic bifurcation]]

==External Links==
*[http://www.acep.org/Clinical---Practice-Management/Focus-On--Bedside-Ultrasound-of-the-Abdominal-Aorta/ ACEP Focus On: Bedside Ultrasound of the Abdominal Aorta]

==See Also==
*[[Ultrasound (main)]]
*[[AAA]]
*[[Aortic dissection]]

==References==
<references/>

[[Category:Ultrasound]]
[[Category:Radiology]]
[[Category:Vascular]]