How effective and safe is the use of trans-cervical ultrasonography in the detection of pediatric peritonsillar abscess (PTA)?
Background: Pediatric PTA is a common infection, particularly in adolescents. Treatment is based on differentiating among PTA, peritonsillar cellulitis (PTC), and tonsillitis (viral or bacterial); however, distinguishing among these entities based on history and physical exam alone may be challenging. Computed tomography (CT) is the most sensitive imaging modality for diagnosis and can identify infection spread beyond the peritonsillar tissues, but cost and increased awareness of radiation exposure prohibit its standard use, especially in pediatrics. Ultrasound (US) has been shown to reliably distinguish PTA from PTC in a number of small-scale studies with adult patients.
Study design: Prospective single-arm cohort study of 43 patients diagnosed between May 2013 and April 2014.
Setting: Children’s National Health System, Washington, D.C.
Synopsis: The US was positive for PTA in 17 patients. Of these, nine had true-positive PTA by the study definition. The greatest measurable dimension of these abscesses ranged from 7 mm to 32 mm, with a mean of 25 mm. Of the eight false-positive US results, abscess diameter ranged from 11 mm to 28 mm, with a mean of 18 mm; three patients had drainage procedures without procurement of pus, and five were medically managed successfully. US finding was the only independent variable found to be correlative with the presence or absence of PTA. Sensitivity and specificity of transcervical ultrasonography in pediatric PTA diagnosis are 100% and 76.5%, respectively. Positive and negative predictive values are 52.9% and 100%, respectively. When a Fisher exact test was performed, the P value was statistically significant, indicating an important correlation between a negative US and patients who were able to be managed medically. Limitations included a small sample size and the inability to enroll a random or continuous sample of patients, possible missing follow-ups, and the impossibility of ensuring that clinicians were universally blinded to all radiographic results, US results, or outside CT impressions.
Bottom line: Transcervical ultrasonography is a useful tool in diagnosing pediatric PTA and identifying patients who will not need surgical intervention, while avoiding undue radiation exposure.
Citation: Fordham MT, Rock AN, Bandarkar A, et al. Transcervical ultrasonography in the diagnosis of pediatric peritonsillar abscess. Laryngoscope. 2015;125:2799-2804.