Abscess Obsession

You’re working a peds shift when a concerned pair of parents brings their three year old child in with a swollen, red, warm bump on his forearm. They first noticed it yesterday, and it has progressively gotten larger. He’s not irritable, but his arm seems to be bothering him. You move the child into a room and examine the lesion, noting that it is fluctuant, warm and erythematous. You make the diagnosis of a soft-tissue abscess.

But is physical exam good enough for the diagnosis?

Physicians have been making the diagnosis of abscesses clinically since the birth of the profession. However, recent studies have found that the inter-rater reliability of the clinical exam to be quite low. One study found a kappa of only 0.48 for abscess presence and 0.43 for whether the abscess would require drainage;[1] a second study picture4had similar findings at 0.39 and 0.43, respectively.[2] These numbers aren’t great. And, because draining an abscess in a young child is likely going to require either conscious sedation or an armada of medical providers armed with a papoose, it’s not something you want to misdiagnose and attempt to drain unnecessarily.

 

Fortunately, the age of ultrasound has given us a tool that can aid us in our diagnosis. A recent review done in our own PEM department pooled six studies comparing physical exam alone with exam with ultrasound for the diagnosis of soft-tissue abscesses. It found that exam alone had a sensitivity of 75-95% and a specificity of 60-84%; supplementing exam with ultrasound showed a modest improvement of 90-98% sensitivity and 67-88% specificity. All studies used the diagnostic gold standard of purulent fluid drainage on initial incision or at follow-up[3].

 

It’s easy, quick, and likely to decrease your need for torturing a small child, so why not throw a probe on it before grabbing the knife?

Aspire to aspirate?

It seems intuitive that using a needle to drain the pus out of an abscess might be less painful, leave a smaller scar, and perhaps require less sedation than incision and drainage. In reality, though, is it as effective?

picture2

The above type of aspiration is out of the scope of practice in the emergency room.

A recent RCT on approximately 101 patients allocated abscesses requiring drainage to either aspiration or traditional incision. Demographics in both groups were comparable. The patients were then followed on days 0, 2 and 7 for these outcomes: 1) resolution or 2) necessity for additional intervention.[4] In the aspiration group, investigators visualized the needle entering the pocket by ultrasonography. In both groups, abscess resolution post-intervention was assessed using ultrasound. The investigators found that at day 2 and 7, incision and drainage showed no difference to aspiration. However, 60% of those who received aspiration failed to show complete drainage on ultrasound immediately post-procedure and required escalation to full incision and drainage.

 

So – if the initial aspiration works, it may be as good as an I & D. However, if it doesn’t work, it will just prolong the process. I’d personally be inclined to just reach for the scalpel, but the opportunity is there for having an open discussion with the patient/guardian regarding both procedures.

 

For really gnarly I & D, see above.

To pack or not to pack

picture3

In or out?

So, you’ve drained your pocket of pus. Do you pack it? If you really think about it, it makes sense not to – isn’t that cloth you’re shoving into the recently infected hole a potential nidus for infection? Also, you’re taking the irritated skin that you just subjected to violation with a scalpel and then just poked several times with a hemostat, and now you’re going to jam some lightly lubricated cloth into that hole right against their fresh wound. Also, they then have to come back and get it removed. All of this is painful.

 

An RCT of 49 patients randomized to receive packing or
no packing and followed at 48 hours and at 10 days found no difference in treatment failure,[5] although both groups had a relatively high rate of re-instrumentation (70% of those in the packing group and 59% in the group that was not packed). Secondary outcomes of pain score, patient satisfaction and patient-rated cosmesis were also not significantly different. A second study of 48 patients found no difference in treatment success between those receiving packing or no packing, but did find that those receiving packing reported more pain immediately post-procedure and at 48 hours.[6]

 

These are both small studies, but they are in agreement that packing may be an unnecessary, painful step.

Can I get out of prescribing antibiotics?

Antibiotic resistance is a problem. Can we cut down on using antibiotics in patients that have undergone I & D?

 

A recent study published in NEJM this year randomized more than 1,000 patients that had received I & D to trimethoprim-sulfamethoxazole or placebo and followed them at 7 and 14 days for clinical cure rates. Investigators found a cure rate of 86.5% in those prescribed trimethoprim-sulfamethoxazole and 74.3% for placebo; this was non-significant.[7] This study is in agreement with previous, smaller investigations that drew the same conclusion.[8],[9],[10]

 

The caveat here is that all of these studies excluded patients with abscesses that were complicated in any way – surrounding cellulitis, immunocompromised (including diabetics), or if the abscess was located on the hands, face or genitals. Additionally, most had an exclusion criteria clause that basically allowed investigators to say “eh, this looks bad, let’s not include them in the trial.”

picture5

Eh, let’s not include this one in the trial.

So, the conclusion here? There’s some suggestion that trimethoprim-sulfamethoxazole may be helpful if the patient has MRSA, although there’s no way to know what’s in that pocket ahead of time. There’s probably no benefit in prescribing antibiotics in healthy patients with uncomplicated abscesses that have been drained. Immunocompromised patients, surrounding cellulitis, or abscesses in difficult-to-drain locations remain to be studied.

 

These data are essentially in agreement with the IDSA 2014 guidelines, which suggest antibiotics for ‘severe or extensive disease,’ abscesses in the presence of cellulitis, signs of systemic illness, immunosuppression, abscesses in difficult-to-drain locations, septic phlebitis, or in extremes of age[11].

LET it be

But what if there was a better way? What if we didn’t even have to violate this poor child’s skin at all?

 

It’s possible that topical anesthetic cream may aid in spontaneous drainage. There’s only been one study on this concept thus far, in which a group evaluated a cohort of 300 patients that presented with abscesses.[12] This department placed topical anesthetic on just over half of patients with abscesses, and found that spontaneous drainage occurred in about a quarter of those in which anesthetic was applied. Importantly, those receiving the topical anesthetic were significantly less likely to require procedural sedation.

This study has obvious methodological issues, but I would argue it’s still worth a shot, as it’s cheap, easy, and even if it’s ineffective at popping the abscess it’ll at least help with the notoriously difficult analgesia required for incision and drainage.

A five-point conclusion

  • Ultrasound – Why not?
    kkqeiuj

    And with that, I’ll leave you with one more lasting visual.

  • Aspiration is effective, but has a high rate of conversion to traditional incision and drainage, thereby prolonging the process
  • Packing after drainage is painful and may not be warranted
  • The IDSA guidelines are consistent with the evidence we have – antibiotics for simple abscesses in the immunocompetent patient aren’t required
  • Try some topical anesthetic, it might mitigate the need for a procedural sedation

 

 

[1] Giovanni JE, Dowd MD, Kennedy C, Michael JG. Inter-examiner agreement in physical examination for children with suspected soft tissue abscesses. Pediatr Emerg Care 2011;27:475-8

[2] Marin JR, Bilker W, Lautenbach E, Alpern ER. Reliability of clinical examinations for pediatric skin and soft-tissue infections. Pediatrics 2010;126:925-30.

[3] Point-of-care Ultrasound for Diagnosis of Abscess in Skin and Soft Tissue Infections.Subramaniam S, Bober J, Chao J, Zehtabchi S. Acad Emerg Med. 2016 Nov;23(11):1298-1306.

[4]Gaspari RJ, Resop D, Mendoza M, Kang T, Blehar D. A randomized controlled trial of incision and drainage versus ultrasonographically guided needle aspiration for skin abscesses and the effect of methicillin-resistant Staphylococcus aureus. Ann Emerg Med. 2011 May;57(5):483-91.e1.

[5]Kessler DO, Krantz A, Mojica M. Randomized trial comparing wound packing to no wound packing following incision and drainage of superficial skin abscesses in the pediatric emergency department. Pediatr Emerg Care. 2012 Jun;28(6):514-7.

[6]O’Malley, G.F., et al. Routine packing of simple cutaneous abscesses is painful and probably unnecessary. Academic emergency medicine: official journal of the Society for Academic Emergency Medicine, 2009. 16(5): p. 470-3.

[7]Talan DA, Mower WR, Krishnadasan A, Abrahamian FM, Lovecchio F, Karras DJ, Steele MT, Rothman RE, Hoagland R, Moran GJ. Trimethoprim-Sulfamethoxazole versus Placebo for Uncomplicated Skin Abscess. N Engl J Med. 2016 March 3; 374(9): 823–832.

[8]Paydar KZ, Hansen SL, Charlebois ED, Harris HW, Young DM. Inappropriate antibiotic use in soft tissue infections. Arch Surg. 2006 Sep;141(9):850-4.

[9]Rajendran PM, Young D, Maurer T, Chambers H, Perdreau-Remington F, Ro P, Harris H. Randomized, double-blind, placebo-controlled trial of cephalexin for treatment of uncomplicated skin abscesses in a population at risk for community-acquired methicillin-resistant Staphylococcus aureus infection. Antimicrob Agents Chemother. 2007 Nov;51(11):4044-8.

[10]Duong M, Markwell S, Peter J, Barenkamp S.Randomized, controlled trial of antibiotics in the management of community-acquired skin abscesses in the pediatric patient. Ann Emerg Med. 2010 May;55(5):401-7.

[11] DL Stevens, AL Bisno, HF Chambers, E Dellinger, E Goldstein, S Gorbach, J Hirschmann, S Kaplan, J Montoya, J Wade. Executive Summary: Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America. Clin Infect Dis. (2014) 59 (2): 147-159

[12] Cassidy-Smith T, Mistry RD, Russo CJ, McCans K, Brown N, Capano-Wehrle LM, Drago LA, Vitale PA, Baumann BM. Topical anesthetic cream is associated with spontaneous cutaneous abscess drainage in children. Am J Emerg Med. 2012 Jan;30(1):104-9.

 

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kkelson

Kyle Kelson, Downstate/Kings County Emergency Medicine resident. @kelsonmd

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