Jerry Boley, PGY-1
The Article: Abscess Incision and Drainage With or Without Ultrasonography: A Randomized Controlled Trial
The Idea: Soft tissue abscess is a common diagnosis made in the ED, and is treated with Incision and drainage (I&D). It has been proven by previous studies that Point of Care Ultrasound can assist in making the diagnosis of an abscess and differentiating it from cellulitis, but there is limited research if using Ultrasound improves the success rate of the I&D.
The Study: This was a prospective randomized controlled trial at a large academic facility that included 125 people who were enrolled and randomized into either use of ultrasound or solely physical exam for the I&D
The control group was then diagnosed and underwent I&D with physical examination alone, while the other group underwent I&D with ultrasound guidance. The ultrasound group was split up in the three unintentional subdivisions depending on performing physician preference. These were using ultrasound only to locate the abscess, using dynamic ultrasounding during the procedure of the I&D, or using the ultrasound to locate the abscess and then again after the I&D to ensure complete drainage.
Inclusion criteria: Adults who presented to ED and diagnosed with superficial skin abscess needing I&D.
Exclusion criteria: Children, patients who appears “clinically ill”, patients with fever or hypotension, abscess secondary to foreign body of animal bite, patients with paronychia, dental abscess, genital abscess, or peritonsillar abscess
Primary Endpoint: failure of I&D therapy, needing a repeat I&D in 10 days
Secondary Endpoints: need for antibiotic treatment or patients with continued pain or purulence
Results: Of the 125 patients enrolled, 107 completed the follow up (54 in ultrasound group, 53 in Physical exam group). The overall failure of therapy rate in both groups combined was 10.3%. However, the failure rate in the Ultrasound group was only 3.7%, while the failure rate in the physical examination group was 17.0 %. This was a difference of 13.3%, with a 95% confidence interval between 0.0 and 19.4%. The 17% failure rate with physical examination is close to previous reported data, but the ultrasound failure rate is admittedly lower than previously reported rates. The physical examination group was also more likely to undergo antibiotic treatment in conjunction with the I&D.
Take-away: The results of this study suggest that point of care ultrasound improves patient outcomes if used while performing an I&D. This study showed a 13% decrease in patients needing a repeat I&D when the ultrasound was used in either locating the best spot for drainage or dynamically visualizing the procedure. Although this study had a CI that included 0, this is most likely due to the small sample size. This is the first randomized clinical trial to exhibit the benefit of ultrasound in this procedure. With Ultrasounds readily available in the ED, they should be incorporated into all I&D’s when possible. The secondary outcome of physical exam requiring more antibiotic treatment was not statistically significant, and there were many confounders (such as more patients with substance abuse disorder) in this group. Therefore, there is no proof that ultrasound has effect on patients and the eventual need for antibiotic treatment.