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Clinical case 038: a AAA eh?

Todays case – 69 yo woman presents to ED with 3 hour history of sharp, severe left abdominal pain. Pain is colicky, radiating down into groin. Urinalysis shows 2+ blood.
So if you read the “frolic with colic” post and the wise comments from the readers you will be asking for an ultrasound – not to diagnose a stone, but to rule out a AAA rupture.  So off to the dark room, maybe you are a keen US type and you have a look yourself.  So you pick up the probe and identify the aorta, then follow it down and is bulges out just below the renal vessels to a max. diameter of 3.9 cm….

This case got me thinking.  I know there are a lot of ED / Gp docs out there who are keen on bedside sonography.  And looking at the aorta is not the toughest utility for those with a small amount of training.  But, the big problem isn’t finding the pathology – rather knwing what it means and what to do about it.  So here is a quick review on the topic.  Most of the info here is pulled from a nice review article, written by my former boss Mr Paul Norman and Dr Powell in Circulation 2007.  It is worth a read if you have time.  The super simple summary is that:

  •  most of what we know about AAAs comes from data which is heavily skewed towards men.
  • Female AAAs grow faster than those in men
  • Women have a higher rupture rate (~4x) for a similar diameter AAA c/w men
  • Women are technically more tricky to do repairs on, esp. endoluminal.
  • Women tend to be managed “non-surgically” in rupture at higher rates than men.
  • Basically, women seem to get the raw end of the deal in every department when it comes to AAA
  • The rates of AAA are climbing faster in women (?late lag effect of smoking)

 

Q:

Most sources quote 30 mm.  If you want to know how to measure this with an US – check out the Ultrasound Village website lecture on AAAs.   

The guidelines vary from organisation to organisation. But, it is likely that you should consider referring women with smaller diameters than men, as they tend to pop earlier.  So the magic number in men is 5 – 5.5 cm for elective repair, it seems that 4.5 – 5 cm probably confers the same rupture risk in women. 

Of course, the job of the GP is to counsel the patient and do so in the context of other comorbidities and the patient’s own risk beliefs.  After all, this is not trivial surgery.  There are serious comlications and an appreciable surgical mortality.

This paper in Annals of Surgery 2010 looked at the mortality rates for elective repair @ 28 days, 1 year and 5 years.  Being older, female and having comorbidities had a large effect on survival – up to 50% mortality in some groups!

The Circulation paper (above) recommends surveillance “every 6 – 12 months using CT or US”. The goal is to detect expansion and intervene early. So – you should be counselling the patient ahead of this – do they want an elective repair if the risk / size goes up?. In my book this means a long chat and some think time for the family before embarking on surveillance.

Well, in short – probably not. There was a Cochrane review in 2007.  This showed no reduction in all-cause mortality for screening for AAAs.  There was a decreased AAA-related death rate in 65 – 79 yo. men.  There was no mortality benefit shown for women, though they were only allowed in one trial and contributed only about 7% of the trial data used.  So not enough evidence (as Bertrand Russell once said!)

So next time you scan a belly and go looking for an aorta, just recall – you might find something, and if what you are doing amounts to screening you just might be opening a whole can of worms for this patient.  Consider their age, sex and comorbidities. You just might save a life, you also might start the ball rolling on a course of events that the patient never wanted.  This is the downside of widespread bedside US for me – finding stuff that you wished you hadn’t!.

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