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Ultrasound-guided needle aspiration “insufficient” for skin abscesses

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – For treatment of uncomplicated skin abscesses, the efficacy of ultrasound-guided needle aspiration is not on par with incision and drainage – it doesn’t even come close.

In a nonblinded randomized controlled trial of about 100 such patients, the overall treatment failure rate was 74% with needle aspiration compared with 20% for incision and drainage.

Treatment failure after ultrasound-guided needle aspiration is “unacceptably high,” Dr. Romolo Gaspari from University of Massachusetts Memorial Medical Center in Worcester and colleagues report in the January 18 online issue of Annals of Emergency Medicine. They say their data do not support use of this drainage technique for skin and soft tissue infections.

“Needle aspiration of an abscess cavity, even with ultrasound guidance, is insufficient and should be abandoned,” Dr. Gaspari told Reuters Health. “This is true for all patients but especially true for patients with methicillin-resistant Staphylococcus aureus (MRSA).”

It’s also important to note, Dr. Gaspari said, that patients with MRSA “did worse regardless of the drainage procedure and independent of antibiotics, which is scary as a clinician.”

Needle aspiration with ultrasound guidance has been advocated for superficial abscesses as a less invasive alternative to incision and drainage, which is considered the primary intervention.

To investigate if the two procedures are equally effective, Dr. Gaspari and colleagues randomly assigned 54 patients with uncomplicated superficial abscesses to incision and drainage with packing and 47 similar patients to ultrasound-guided needle aspiration. They defined successful treatment as a combination of sonographic resolution and clinical resolution of the signs and symptoms of ongoing infection at day 7.

According to the investigators, the overall success rate was 26% with needle aspiration compared with 80% for incision and drainage, a difference of 54%.

“I was very surprised by the results as I initially designed this trial thinking that ultrasound-guided needle aspiration would be equivalent to incision and drainage,” Dr. Gaspari said. “We had seen some failures from needle aspiration but I assumed that this was because of a lack of ultrasound guidance.”

Staphylococcus aureus was isolated in 64 of 101 patients (63%) and 33 of the isolates (52%) were community-acquired MRSA. There was no difference in the percentage of MRSA in either group.

Overall success rates of both drainage methods were lower in patients with than without MRSA – 8% versus 55% for needle aspiration and 61% versus 89% for incision and drainage.

In a multivariate analysis comparing outcomes of MRSA and non-MRSA, failure of therapy was independent of drainage procedure, making MRSA an independent risk factor for failure of therapy.

In their report, the researchers say needle aspiration may continue to have limited clinical indications for abscesses for which immediate incision and drainage is less desirable, such as abscesses on the face. They advise, based on their experience, that any needle aspiration be accompanied by ultrasound guidance.

Reference:

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. Published online January 18, 2011.