It has been long held dogma that one should irrigate the
abscess cavity after ED incision and drainage. But as these authors point out,
there is no high quality evidence to
support this practice.
Unfortunately, this is still the case.
This RCT was conducted in Fresno, California; better known
as MRSA country. They enrolled 209 patients
with all kinds of abscesses to
irrigation vs. no irrigation. This pragmatic design allowed for packing and
antibiotics at the discretion of the doctor.
The primary outcome
was ‘further intervention’ as defined by repeat I&D, antibiotic change or
abscess related hospital admission.
Results? No
difference with 15% vs. 13% meeting the primary outcome in the irrigation vs.
no irrigation group respectively.
So, we should stop irrigating abscesses!?
Unfortunately, the
jury is still out...
This was a small underpowered
study with heterogeneous patient population. I don’t think we can make
conclusions about the larger pus pockets with lots of necrotic material.
The irrigation
was pretty half hearted. This was not standardized and the authors suggest
about 100ml was used. Therefore, it is not surprising that such a minor intervention
resulted in no difference. Perhaps more aggressive efforts would have achieved
better outcomes? Once again, who knows?
Usually randomization evens out the confounders, but for some reason the irrigation group got more
packing. In addition, they got more antibiotics at 90% vs. 72% of the time! That’s a lot of antibiotics for cutaneous
abscesses and certainly not reflective of my practice (low MRSA prevalence).
The determination of the primary outcome was by 30 day
telephone interview. This is far from perfect and could have led to some miscalls.
This is better known as non-differential misclassification that can dilute the
results towards the null hypothesis. Put another way, this could have watered things down (no pun intended).
The Annals of EM editors capsule summary concludes, “Irrigation
of abscesses appears unnecessary after incision and drainage.” I guess this all
depends on how you interpret ‘appears.’
In summary, this was a small study that still leaves us with
more questions than answers. It gets
points for originality. Maybe it's right, but unfortunately we are still in a necrotic mess.
Covering:
Chinnock, B,
Hendy GW, Irrigation of Cutaneous Abscesses Does Not Improve Treatment Success.
Ann Emerg Med. 2016;67:379-383.
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