87 / 232
The sensitivity and specificity of US in this study
were 100% and 76.5%, respectively. Our data are similar
to that of other studies. Araujo Filho et al. reported sen-
sitivity and specificity as 80% and 92.8%, respectively,
for transcervical US, primarily in adult patients.
13
The
differences in anatomy and amount of subcutaneous tis-
sue between the adult and pediatric populations may
account for some of the variation between these statis-
tics; however, both studies highlight the utility of this
modality in evaluating this infectious process. In this
study, it is important to note that of the patients who
had a negative US, none failed medical management.
US is a very sensitive tool for identifying fluid col-
lections within tissue planes; therefore, we were not sur-
prised to have a number of false positives, as oftentimes
small fluid collections on CT or US are reported. Several
patients who were successfully managed medically were
diagnosed with PTA both on physical exam and US.
These patients, who responded promptly to initial medi-
cal therapy prior to procedural intervention, or whose
parents opted for a more conservative medical treatment
in lieu of surgical drainage, were followed clinically.
Given that the peritonsillar regions of all exclusively
medically managed children were never opened, it is
possible that small collections of purulence may have
been found on some of these patients. With this is mind,
we may have overcalled the number of false positives.
Our study design did not mandate exploration of every
peritonsillar space or require CT on every patient. For
statistical integrity, however, children with positive
ultrasounds managed medically successfully were not
discarded, but rather counted as false positives. Based
on these data, we believe that smaller PTAs may resolve
with medical therapy alone; therefore, our study results
likely represent an underestimation of ultrasound’s spec-
ificity for PTA.
When comparing the sizes of the measured
abscesses in the true- and false-positive groups, a statis-
tically significant difference was found, with the false
positives measuring smaller. Although US is capable of
visualizing small PTAs in pediatric patients, the spec-
trum of peritonsillar and intratonsillar findings may
lead a radiologist to overcall an abscess. This conclusion
assumes that all of the false positives indeed did not
have purulence. If purulent cavities were in fact present
on some of these patients, then smaller abscesses either
respond to medical management alone and/or are diffi-
cult to locate during procedural interventions.
Based on these findings, we developed an algorithm
for PTA management (Fig. 5), which is now utilized at
Fig. 3. Identical images of a right
peritonsillar abscess (PTA) with the
image on the right labeled. The PTA
is outlined by a dashed white line.
The tonsil (white arrow heads) and
submandibular gland (SMG) are
once again identified.
Fig. 4. Ultrasound and computed tomography (CT) images from the same patient. The far left and center images are identical, the center
image being marked to identify the structures. The irregularly marginated hypoechoic region (outlined by white dashed line) is consistent
with a left peritonsillar abscess. Again the tonsil (white arrow heads) and submandibular gland (SMG) are labeled for reference. The CT
image (far right) shows the corresponding abscess (black arrow).
Laryngoscope 125: December 2015
Fordham et al.: Transcervical US in Pediatric PTA
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