DIAGNOSTIC IMAGING REVIEW
Bedside ultrasound to evaluate a severe sore throat Alexander C. Lee, MSHS, PA-C; Hamid Shokoohi, MD, MPH, RDMS; Kyla Newman, MSHS, PA-C
CASE A 23-year-old man presented to the ED complaining of unilateral throat pain and dysphagia that had progressively worsened over the past 5 days. Two days ago, he was diagnosed with presumed strep pharyngitis at an urgent care center and was prescribed amoxicillin, tramadol, and ibuprofen. However, his symptoms worsened despite this treatment. On physical examination, his vital signs were stable with a temperature of 99.1° F (37.3° C), BP of 129/79 mm Hg, heart rate of 83 beats per minute, and SpO2 of 100% on room air. He was alert and oriented, without acute distress. Although he had a muffled voice and marked trismus, he could manage his secretions and protect his airway. A posterior pharyngeal examination revealed unilateral right-sided swelling with purulent exudate, erythema, and friable mucosa. The left tonsil was 2+ and the right was 4+ with uvula deviation to the left. Rapid strep and monospot tests were both negative. An experienced ED sonographer completed a bedside ultrasound examination of the submandibular space using a transcutaneous approach with a high-frequency linear transducer. What do the images show? DISCUSSION The right lateral neck ultrasound shows a heterogeneous and hypoechoic tonsil with an anechoic area medially, consistent with a peritonsillar abscess (Figure 1). Color flow doppler indicates increased vascularity to the tonsil but no vascularity within the abscess, differentiating it from a blood vessel (Figure 2). Peritonsillar abscess formation usually is preceded by tonsillitis that perforates the tonsillar capsule and lets it extend into the peritonsillar space. Local inflammation Alexander C. Lee practices emergency medicine with Medical Faculty Associates and is a clinical instructor of emergency medicine at George Washington University in Washington, D.C. Hamid Shokoohi practices emergency medicine with Medical Faculty Associates and is an assistant professor of emergency medicine at George Washington University. Kyla Newman practices emergency medicine with Medical Faculty Associates. The authors have disclosed no potential conflicts of interest, financial or otherwise. Bryan Walker, MHS, PA-C, department editor DOI: 10.1097/01.JAA.0000450812.21330.a7 Copyright © 2014 American Academy of Physician Assistants
42
www.JAAPA.com
FIGURE 1. Transverse two-dimensional image of the right
tonsil, revealing an enlarged, heterogeneous and hypoechoic tonsil (green arrow) and medial anechoic abscess formation (red arrow)
with phlegmonous changes, characteristic of peritonsillar cellulitis, progresses to peritonsillar abscess as pus collects between the tonsillar capsule and the superior constrictor muscle of the pharynx.1 Peritonsillar abscess is a known complication of streptococcal pharyngitis, occurs most commonly in the same patient population (older teens and young adults) and is similarly more prevalent in the winter and early spring.2 Other commonly isolated agents from peritonsillar abscess include oral anaerobes, Staphylococcus aureus, and Haemophilus influenzae. Noninfectious causes include obstruction and inflammation of the Weber glands, which are salivary glands located superior to the tonsil within the soft palate. Smoking appears to be a major risk factor in such cases.1-3 Clinical findings The hallmarks of peritonsillar abscess include severe odynophagia, dysphagia, and a muffled “hot potato voice.” Trismus is a common finding, resulting from local inflammation of the internal pterygoid muscle.1,2 Patients typically present with constitutional symptoms including fever and tachycardia and often appear ill. An oropharyngeal examination will reveal palatal asymmetry Volume 27 • Number 7 • July 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Bedside ultrasound to evaluate a severe sore throat
with medial displacement of the tonsil and uvula deviation toward the unaffected side. Traditional diagnostic methodology Differentiating peritonsillar abscess from peritonsillar cellulitis based solely on physical examination findings is difficult, and more advanced techniques are needed to accurately diagnose this potentially life-threatening condition. In one study, physical examinations performed by otolaryngologists showed a sensitivity of 78% and specificity of 50% in diagnosing peritonsillar abscess versus peritonsillar cellulitis.4,5 Aspiration of a suspected peritonsillar abscess with an 18-gauge needle can be diagnostic and therapeutic, but can cause the patient significant pain and anxiety, diminishing its usefulness as a primary diagnostic tool. Aspiration also has a high false negative rate (about 12%), necessitating follow-up otolaryngology consultation or CT scans if aspiration attempts were unsuccessful.3,5 Contrastenhanced soft tissue neck CT has a sensitivity approaching 100% and a specificity ranging between 75% and 82% depending on the size of the abscess.6 However, this test exposes patients to potentially nephrotoxic and allergenic IV contrast media, and a relatively high dose of ionizing radiation—a situation made less ideal by the fact that patients presenting with suspected peritonsillar abscess tend to be in their late teens or early adulthood.6 Sonographic evaluation Bedside ultrasound is becoming more widely available in acute care settings, and provider confidence with this imaging modality is increasing. A suspected peritonsillar abscess traditionally is examined with an endocavitary transducer via an intraoral approach to the peritonsillar space. A prospective, randomized clinical trial showed the diagnostic accuracy of initial bedside intraoral ultrasound examination to be 100%,
compared with 64% for needle aspiration alone.3 Like diagnostic needle aspiration, the technique is uncomfortable and challenging in the setting of severe trismus. Newer evidence in the otolaryngology literature suggests that a transcutaneous approach with a linear probe—the technique demonstrated in this case study—has similar sensitivity, specificity, and diagnostic accuracy to the intraoral approach.7 In a recent case study, an emergency medicine provider was able to aspirate a peritonsillar abscess under ultrasound guidance via a transcutaneous approach.4 During this procedure (demonstrated by our team on a different patient in Figure 3), an assistant holds the transducer while the provider uses both hands for the aspiration procedure. The provider’s view of the peritonsillar space is unimpeded by the endocavitary transducer. Ultrasound examination by either technique also can be used to locate neighboring vascular structures—namely the internal carotid artery and the internal jugular vein—in relation to the abscess using color flow doppler. Postprocedure examination can be used to demonstrate resolution of the abscess. Other intangible benefits to the initial use of a bedside ultrasound examination include shorter patient length of stay (176 minutes for ultrasound alone versus 242 minutes for attempted needle aspiration followed by either CT scan or otolaryngology consultation) and decreased need for otolaryngology consultation (7% for ultrasound versus 50% for initial attempted needle aspiration).3
FIGURE 2. Color doppler image of the right tonsil revealing an
enlarged, heterogeneous and hypoechoic tonsil (green arrow) and medial anechoic abscess formation (red arrow)
FIGURE 3. External submandibular probe placement for evalu-
ation and ultrasound-guided peritonsillar abscess drainage
JAAPA Journal of the American Academy of Physician Assistants
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
www.JAAPA.com
43
DIAGNOSTIC IMAGING
Potential disadvantages of sonographic evaluation Bedside ultrasound examination to differentiate peritonsillar abscess from peritonsillar cellulitis using either an intraoral or transcutaneous approach should only be performed by providers trained in the techniques. Ultrasound is an adjunct to history and physical examination. High clinical suspicion should always trump a negative bedside ultrasound, given ultrasound’s limited ability to evaluate for extension of a peritonsillar abscess into deeper neck spaces, particularly in adult patients. In equivocal cases, a CT scan might be necessary.6 TREATMENT Early treatment of peritonsillar cellulitis with broadspectrum antibiotics often is sufficient to resolve symptoms without abscess formation, assuming treatment is started within 48 hours of pain onset. Frank pus typically forms by day 5 if antibiotics are not started. Once pus has formed, definitive management is needle aspiration or incision and drainage. Bedside ultrasound may reduce the need for formal otolaryngology consultation in suspected peritonsillar abscess, but in our case an otolaryngology resident seeing patients in the ED was involved in the definitive management. He anesthetized the region first with benzocaine spray followed by local infiltration with lidocaine, aspirated the abscess cavity with an 18-gauge needle, then made a small incision at the aspiration site with a No. 15 blade scalpel. Gentle superficial probing of the abscess cavity lysed loculations and allowed for complete drainage. Follow-up within 48 hours is recommended for all patients, and those who are hemodynamically unstable or at risk for airway compromise should be admitted for IV antibiotics, rehydration, and airway monitoring. Our patient was discharged home on oral clindamycin and followed up 2 days later without complication.
CONCLUSION Differentiating peritonsillar abscess from peritonsillar cellulitis by physical examination alone is unreliable, and the potential to misdiagnose this serious condition cannot be understated. Diagnostic needle aspiration, given its high false negative rate, associated pain, and limitations due to trismus, should be avoided if bedside ultrasound examination is possible. Using a transcutaneous approach with the more widely available and technically less challenging linear array transducer offers medical providers the opportunity to make the diagnosis of peritonsillar abscess with high sensitivity and specificity, decreases the need for CT scans and specialty consultation, and may significantly reduce patient length of stay and associated healthcare costs. JAAPA REFERENCES 1. Brook I. Microbiology and management of peritonsillar, retropharyngeal, and parapharyngeal abscesses. J Oral Maxillofac Surg. 2004;62(12):1545-1550. 2. Tintinalli J, Stapczynski J, Ma J, et al. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York, NY: McGraw Hill; 2011:1850. 3. Costantino TG, Satz WA, Dehnkamp W, Goett H. Randomized trial comparing intraoral ultrasound to landmark-based needle aspiration in patients with suspected peritonsillar abscess. Acad Emerg Med. 2012;19(6):626-631. 4. Rehrer M, Mantuani D, Nagdev A. Identification of peritonsillar abscess by transcutaneous cervical ultrasound. Am J Emerg Med. 2013;31(1):267.e1-267.e3. 5. Scott PM, Loftus WK, Kew J, et al. Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis. J Laryngol Otol. 1999;113 (3):229-232. 6. Maroldi R, Farina D, Ravanelli M, et al. Emergency imaging assessment of deep neck space infections. Semin Ultrasound CT MR. 2012;33(5):432-442. 7. Araujo Filho BC, Sakae FA, Sennes LU, et al. Intraoral and transcutaneous cervical ultrasound in the differential diagnosis of peritonsillar cellulitis and abscesses. Braz J Otorhinolaryngol. 2006;72(3):377-381.
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44
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Volume 27 • Number 7 • July 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Bedside ultrasound to evaluate a severe sore throat Alexander C. Lee, MSHS, PA-C; Hamid Shokoohi, MD, MPH, RDMS; Kyla Newman, MSHS, PA-C
CASE A 23-year-old man presented to the ED complaining of unilateral throat pain and dysphagia that had progressively worsened over the past 5 days. Two days ago, he was diagnosed with presumed strep pharyngitis at an urgent care center and was prescribed amoxicillin, tramadol, and ibuprofen. However, his symptoms worsened despite this treatment. On physical examination, his vital signs were stable with a temperature of 99.1° F (37.3° C), BP of 129/79 mm Hg, heart rate of 83 beats per minute, and SpO2 of 100% on room air. He was alert and oriented, without acute distress. Although he had a muffled voice and marked trismus, he could manage his secretions and protect his airway. A posterior pharyngeal examination revealed unilateral right-sided swelling with purulent exudate, erythema, and friable mucosa. The left tonsil was 2+ and the right was 4+ with uvula deviation to the left. Rapid strep and monospot tests were both negative. An experienced ED sonographer completed a bedside ultrasound examination of the submandibular space using a transcutaneous approach with a high-frequency linear transducer. What do the images show? DISCUSSION The right lateral neck ultrasound shows a heterogeneous and hypoechoic tonsil with an anechoic area medially, consistent with a peritonsillar abscess (Figure 1). Color flow doppler indicates increased vascularity to the tonsil but no vascularity within the abscess, differentiating it from a blood vessel (Figure 2). Peritonsillar abscess formation usually is preceded by tonsillitis that perforates the tonsillar capsule and lets it extend into the peritonsillar space. Local inflammation Alexander C. Lee practices emergency medicine with Medical Faculty Associates and is a clinical instructor of emergency medicine at George Washington University in Washington, D.C. Hamid Shokoohi practices emergency medicine with Medical Faculty Associates and is an assistant professor of emergency medicine at George Washington University. Kyla Newman practices emergency medicine with Medical Faculty Associates. The authors have disclosed no potential conflicts of interest, financial or otherwise. Bryan Walker, MHS, PA-C, department editor DOI: 10.1097/01.JAA.0000450812.21330.a7 Copyright © 2014 American Academy of Physician Assistants
42
www.JAAPA.com
FIGURE 1. Transverse two-dimensional image of the right
tonsil, revealing an enlarged, heterogeneous and hypoechoic tonsil (green arrow) and medial anechoic abscess formation (red arrow)
with phlegmonous changes, characteristic of peritonsillar cellulitis, progresses to peritonsillar abscess as pus collects between the tonsillar capsule and the superior constrictor muscle of the pharynx.1 Peritonsillar abscess is a known complication of streptococcal pharyngitis, occurs most commonly in the same patient population (older teens and young adults) and is similarly more prevalent in the winter and early spring.2 Other commonly isolated agents from peritonsillar abscess include oral anaerobes, Staphylococcus aureus, and Haemophilus influenzae. Noninfectious causes include obstruction and inflammation of the Weber glands, which are salivary glands located superior to the tonsil within the soft palate. Smoking appears to be a major risk factor in such cases.1-3 Clinical findings The hallmarks of peritonsillar abscess include severe odynophagia, dysphagia, and a muffled “hot potato voice.” Trismus is a common finding, resulting from local inflammation of the internal pterygoid muscle.1,2 Patients typically present with constitutional symptoms including fever and tachycardia and often appear ill. An oropharyngeal examination will reveal palatal asymmetry Volume 27 • Number 7 • July 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Bedside ultrasound to evaluate a severe sore throat
with medial displacement of the tonsil and uvula deviation toward the unaffected side. Traditional diagnostic methodology Differentiating peritonsillar abscess from peritonsillar cellulitis based solely on physical examination findings is difficult, and more advanced techniques are needed to accurately diagnose this potentially life-threatening condition. In one study, physical examinations performed by otolaryngologists showed a sensitivity of 78% and specificity of 50% in diagnosing peritonsillar abscess versus peritonsillar cellulitis.4,5 Aspiration of a suspected peritonsillar abscess with an 18-gauge needle can be diagnostic and therapeutic, but can cause the patient significant pain and anxiety, diminishing its usefulness as a primary diagnostic tool. Aspiration also has a high false negative rate (about 12%), necessitating follow-up otolaryngology consultation or CT scans if aspiration attempts were unsuccessful.3,5 Contrastenhanced soft tissue neck CT has a sensitivity approaching 100% and a specificity ranging between 75% and 82% depending on the size of the abscess.6 However, this test exposes patients to potentially nephrotoxic and allergenic IV contrast media, and a relatively high dose of ionizing radiation—a situation made less ideal by the fact that patients presenting with suspected peritonsillar abscess tend to be in their late teens or early adulthood.6 Sonographic evaluation Bedside ultrasound is becoming more widely available in acute care settings, and provider confidence with this imaging modality is increasing. A suspected peritonsillar abscess traditionally is examined with an endocavitary transducer via an intraoral approach to the peritonsillar space. A prospective, randomized clinical trial showed the diagnostic accuracy of initial bedside intraoral ultrasound examination to be 100%,
compared with 64% for needle aspiration alone.3 Like diagnostic needle aspiration, the technique is uncomfortable and challenging in the setting of severe trismus. Newer evidence in the otolaryngology literature suggests that a transcutaneous approach with a linear probe—the technique demonstrated in this case study—has similar sensitivity, specificity, and diagnostic accuracy to the intraoral approach.7 In a recent case study, an emergency medicine provider was able to aspirate a peritonsillar abscess under ultrasound guidance via a transcutaneous approach.4 During this procedure (demonstrated by our team on a different patient in Figure 3), an assistant holds the transducer while the provider uses both hands for the aspiration procedure. The provider’s view of the peritonsillar space is unimpeded by the endocavitary transducer. Ultrasound examination by either technique also can be used to locate neighboring vascular structures—namely the internal carotid artery and the internal jugular vein—in relation to the abscess using color flow doppler. Postprocedure examination can be used to demonstrate resolution of the abscess. Other intangible benefits to the initial use of a bedside ultrasound examination include shorter patient length of stay (176 minutes for ultrasound alone versus 242 minutes for attempted needle aspiration followed by either CT scan or otolaryngology consultation) and decreased need for otolaryngology consultation (7% for ultrasound versus 50% for initial attempted needle aspiration).3
FIGURE 2. Color doppler image of the right tonsil revealing an
enlarged, heterogeneous and hypoechoic tonsil (green arrow) and medial anechoic abscess formation (red arrow)
FIGURE 3. External submandibular probe placement for evalu-
ation and ultrasound-guided peritonsillar abscess drainage
JAAPA Journal of the American Academy of Physician Assistants
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
www.JAAPA.com
43
DIAGNOSTIC IMAGING
Potential disadvantages of sonographic evaluation Bedside ultrasound examination to differentiate peritonsillar abscess from peritonsillar cellulitis using either an intraoral or transcutaneous approach should only be performed by providers trained in the techniques. Ultrasound is an adjunct to history and physical examination. High clinical suspicion should always trump a negative bedside ultrasound, given ultrasound’s limited ability to evaluate for extension of a peritonsillar abscess into deeper neck spaces, particularly in adult patients. In equivocal cases, a CT scan might be necessary.6 TREATMENT Early treatment of peritonsillar cellulitis with broadspectrum antibiotics often is sufficient to resolve symptoms without abscess formation, assuming treatment is started within 48 hours of pain onset. Frank pus typically forms by day 5 if antibiotics are not started. Once pus has formed, definitive management is needle aspiration or incision and drainage. Bedside ultrasound may reduce the need for formal otolaryngology consultation in suspected peritonsillar abscess, but in our case an otolaryngology resident seeing patients in the ED was involved in the definitive management. He anesthetized the region first with benzocaine spray followed by local infiltration with lidocaine, aspirated the abscess cavity with an 18-gauge needle, then made a small incision at the aspiration site with a No. 15 blade scalpel. Gentle superficial probing of the abscess cavity lysed loculations and allowed for complete drainage. Follow-up within 48 hours is recommended for all patients, and those who are hemodynamically unstable or at risk for airway compromise should be admitted for IV antibiotics, rehydration, and airway monitoring. Our patient was discharged home on oral clindamycin and followed up 2 days later without complication.
CONCLUSION Differentiating peritonsillar abscess from peritonsillar cellulitis by physical examination alone is unreliable, and the potential to misdiagnose this serious condition cannot be understated. Diagnostic needle aspiration, given its high false negative rate, associated pain, and limitations due to trismus, should be avoided if bedside ultrasound examination is possible. Using a transcutaneous approach with the more widely available and technically less challenging linear array transducer offers medical providers the opportunity to make the diagnosis of peritonsillar abscess with high sensitivity and specificity, decreases the need for CT scans and specialty consultation, and may significantly reduce patient length of stay and associated healthcare costs. JAAPA REFERENCES 1. Brook I. Microbiology and management of peritonsillar, retropharyngeal, and parapharyngeal abscesses. J Oral Maxillofac Surg. 2004;62(12):1545-1550. 2. Tintinalli J, Stapczynski J, Ma J, et al. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York, NY: McGraw Hill; 2011:1850. 3. Costantino TG, Satz WA, Dehnkamp W, Goett H. Randomized trial comparing intraoral ultrasound to landmark-based needle aspiration in patients with suspected peritonsillar abscess. Acad Emerg Med. 2012;19(6):626-631. 4. Rehrer M, Mantuani D, Nagdev A. Identification of peritonsillar abscess by transcutaneous cervical ultrasound. Am J Emerg Med. 2013;31(1):267.e1-267.e3. 5. Scott PM, Loftus WK, Kew J, et al. Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis. J Laryngol Otol. 1999;113 (3):229-232. 6. Maroldi R, Farina D, Ravanelli M, et al. Emergency imaging assessment of deep neck space infections. Semin Ultrasound CT MR. 2012;33(5):432-442. 7. Araujo Filho BC, Sakae FA, Sennes LU, et al. Intraoral and transcutaneous cervical ultrasound in the differential diagnosis of peritonsillar cellulitis and abscesses. Braz J Otorhinolaryngol. 2006;72(3):377-381.
Author Services tab, and click on Information for Authors and Reviewers
44
www.JAAPA.com
Volume 27 • Number 7 • July 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
