+ AAA Assessment Chris Lowry

+ Clinical Indications Discussion about technique Hands on practice Further learning resources

+ Clinical Indications Patients >50 yo Abdominal, back, flank pain “Renal Colic” in this age group “collapse ?Cause” Could be a consideration in causes of cardiac arrest

+ Technique Patient positioning Supine is most practical Expose abdomen adequately, from epigastrium to suprapubic Dictated by clinical picture Probe Curvilinear probe Standard MHz

+ Technique DEFG Depth – start with depth at around 15-20cm Environment – ensure you can adequate see the image, lights out etc Focus – Focus set at 10cm (we can look at this in the practical session Gain optimised to view image

+ Technique Begin with the probe just below the xiphisternum – probe in transverse position and with marker to patients right

+ Technique Identify landmarks Verterbral body is best object to identify for orientation (identified by bright bony edge and acoustic shadow) Optimise depth to “fill the screen” with the relevant information Optimise gain and focus Then attempt to identify vessels Aorta IVC Attempt to identify other vessels

+ Other vessels Usually SMA Useful surrogate for the level of the renal arteries, which are harder to see Therefore if AAA identified below origin of SMA, AAA is infrarenal (commonest) Can also sometimes visual Splenic vessels

+ Aorta vs IVC

+ Technique Measure Aorta from OUTER wall to OUTER wall Can underestimate size of Ao if thrombus is present and only the lumen is measured Normal diameter is <3cm Ao tapers as it descends, therefore an increasing Ao as moving distally can also be suspicious

+ Technique Next sweep the probe, in the transverse position, distally and obtain an image in the mid portion of the Aorta Move it further distally and obtain a further image just before the bifurcation of the Aorta (generally around the umbilicus)

+ Technique Repeat the procedure, but this time with the probe in the longitudinal position

+ Technique

+ Obtain measurements in longitudinal section also, from outer wall to outer wall Essentially at least 4 measurements 3 transverse views – Prox, mid Distal 1 Longitudinal view If further clinical concern - can attempt to repeat procedure with the iliac arteries

+ Pitfalls Bowel gas Direct pressure on the abdomen can displace bowel gas and improve view Obesity Can make US challenging, try optimising depth etc If images prove difficult Move patient into left lateral Can view prox. Aorta in the RUQ through the liver Make sure to measure outer wall to outer wall

+ What US can and can’t tell you Can Identify Presence of Aneurysm (97-100% sensitive, operator dependent) Presence of dissection Cant identify Ruptured AAA If free fluid present, high mortality Cannot R/O dissection if still a clinical concern