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Despite these limitations, the authors still find the exam and its interpretation to be well within the skill set of radiologists, otolaryngologists, and emergency physicians alike. Our study was limited by our small sample size and our inability to enroll a random or continuous sample of patients. Missing follow-up may have biased our results, as it is certainly possible that patients presented to other hospitals with recurrent or persistent symptoms after having been evaluated and treated initially at ours. Last, it was impossible to ensure that clinicians were universally blinded to all radiographic results, ultrasound, or outside CT impressions. This lack of blinding may have biased clinical decision making in some circumstances. Overall, our study results support the use of trans- cervical US in the workup of pediatric PTA. Although not all children who present with signs and symptoms consistent with a PTA warrant imaging, the authors believe that US will prove to be the optimal modality in evaluating these patients when imaging is indicated. In addition to being safe and well-tolerated, statistically significant data show that US is highly predictive in identifying those patients with equivocal PTA who are likely to improve without the need for surgical interven- tion. Furthermore, US findings (more so than clinical diagnosis or age) are highly correlative with the pres- ence or absence of PTA. Even so, additional prospective studies are needed to better elucidate the role this tech- nology will play in these patients and to better define which PTAs can be best managed medically versus surgically. CONCLUSION This study is the first to investigate the efficacy of transcervical ultrasound in the diagnosis of pediatric PTA. Our results show that ultrasound is a reliable and useful tool in the evaluation of these children and is highly correlative with surgical findings and clinical out- comes. The authors believe that this study should bol- ster a transition away from CT as the imaging modality of choice. Although the authors still maintain that there is a role for CT in the evaluation of complex head and neck infections, we also emphasize the physician’s role in the thoughtful use of this modality in light of docu- mented concerns over radiation exposure in children. BIBLIOGRAPHY 1. Millar KR, Johnson DW, Drummond D, Kellner JD. Suspected peritonsil- lar abscess in children. Pediatr Emerg Care 2007;23:431–438. 2. Dalton RE, Abedi E, Sismanis A. Bilateral peritonsillar abscesses and quinsy tonsillectomy. J Natl Med Assoc 1985;77:807–812. 3. Brook I. Microbiology and management of peritonsillar, retropharyngeal, and parapharyngeal abscesses. J Oral Maxillofac Surg 2004;62:1545– 1550. 4. Scott PMJ, Loftus WK, Kew J, Ahuja A, Yue V, Van Hasselt CA. Diagnosis of peritonsillar infections: a prospective study of ultrasound, computer- ized tomography and clinical diagnosis. J Laryngol Otol 1999;113:229– 232. 5. Powell J, Wilson JA. An evidence-based review of peritonsillar abscess. Clin Otolaryngol 2012;37:136–145. 6. Smith-Bindman R, Lipson J, Marcus R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med 2009;169:2078– 2086.

Fig. 5. This generalized basic management algorithm has been adopted by our institution. CT 5 computed tomography; PTA 5 peritonsillar abscess.

our institution. For evaluation of equivocal PTA, we have eliminated CT scans from our workup protocol alto- gether. Patients are managed medically if they have a negative US. Whether or not they are admitted for ini- tiation of treatment is contingent on severity of symp- toms and overall clinical picture. If the US is positive, history and physical exam dictate treatment. If the physical exam also suggests PTA, then drainage is attempted pending consent. If the physical exam is equivocal, then medical therapy is attempted first. In cases of a difficult or limited exam, one may elect to attempt drainage of larger abscesses ( > 15 mm) seen on US while attempting medical management of ones that are smaller and/or less symptomatic. As has been described in previous studies on pediatric deep neck space infections as well as pediatric PTA, some fluid col- lections are likely to respond to antibiotic therapy alone. 16,18–20 In our study, six children were transferred to our institution with prior CT scans. All of these patients were enrolled and received a transcervical US per study protocol. Although the aim of the study was not to com- pare these two modalities, it is worth noting that the final US read was identical to the CT findings in five of six cases. In the one case where the two modalities dif- fered, the physical exam and CT were suggestive of PTA, whereas the US was negative. When that child was taken to the operating room for drainage, no purulence was found. In summary, we believe that there are several sig- nificant advantages to using ultrasound as the primary diagnostic tool for equivocal pediatric PTA. In addition to cost reduction compared to CT, the other obvious advantage is the avoidance of undue radiation exposure in children. Given how well US is tolerated and how quickly it can be performed, one may also argue that sedation requirements will be lower than when using other imaging modalities that may require intravenous injections and/or sedation simply to complete the exam. Moreover, US provides real-time imaging with excellent assessment of the tonsils and peritonsillar space. Inter- estingly, the images from this study may even begin to help differentiate intratonsillar from peritonsillar proc- esses, both of which may present with a largely swollen and asymmetric oropharynx. Perhaps the largest impediment to the use of US is the interuser variability. Although the technique itself is rather simple, interpreting the images accurately involves appreciating the nuances of this modality.

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