Article, Dentistry

Comparison of bedside ultrasound and panorex radiography in the diagnosis of a dental abscess in the ED

Brief Report

Comparison of bedside ultrasound and panorex radiography in the diagnosis of a dental abscess in the ED

Srikar Adhikari MD a,?, Michael Blaivas MD b, Lina Lander ScD c

aDepartment of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE 68198-1150, USA

bDepartment of Emergency Medicine, Northside Hospital-Forsyth, Cuming, GA 30041, USA

cDepartment of Epidemiology, University of Nebraska Medical Center, Omaha, NE 68198-4395, USA

Received 7 December 2009; revised 7 February 2010; accepted 7 March 2010

Abstract

Objective: The purpose of the study was to compare bedside ultrasound (US) and panorex radiography in the diagnosis of a dental abscess in emergency department (ED).

Methods: A retrospective review of ED records of adult patients with atraumatic facial pain, swelling, and toothache who received a panorex x-ray and bedside US was performed. Medical records were reviewed for ED evaluation and disposition. Sensitivity and specificity of US and panorex x-ray were calculated to determine the clinical utility of the 2 tests.

Results: A total of 19 patients were identified. No periapical abscess was reported on panorex x-rays in 7 (37%) of 19 patients. Ultrasound agreed with panorex x-rays in 6 (86%) of 7 cases. One case where US disagreed with x-rays was evaluated by dentistry consultants; and incision and drainage were performed, confirming the presence of an abscess. An x-ray diagnosis of periapical abscess was made in 12 (63%) of 19 patients. Ultrasound agreed with panorex x-ray in 10 (83%) of 12 cases. In 1 of the 2 cases where US disagreed with panorex x-rays, x-ray abnormalities were reported on the nonsymptomatic side. The other patient was given antibiotics and recommended outpatient follow- up. Follow-up information was not available to further confirm the presence of an abscess. Assuming that the patient who was lost to follow-up had dental abscess, the sensitivity and specificity of US in diagnosing a dental abscess were 92% and 100%, respectively.

Conclusions: Bedside US is nonionizing, is readily available, and can provide an alternative to panorex x-rays in the evaluation of a dental abscess in ED.

(C) 2011

Introduction

Patients with dental complaints comprise a significant portion of patients presenting to emergency departments (EDs) in the United States [1]. In recent years, there has been a substantial increase in the number of patients presenting to the ED with dental problems [2]. Factors responsible for

* Corresponding author. Tel.: +1 402 559 3586.

E-mail address: [email protected] (S. Adhikari).

increasing ED use for dental-related symptoms include changes in reimbursement policies, rapidly rising health care costs, and lack of Dental insurance [3-5]. Approximately 44% of Americans lack dental insurance and thus experience difficulty in accessing dental care when they need it [6]. Emergency departments have become a principal source of dental care for these patients who lack access to office-based dental services.

Odontogenic infections represent most of the dental problems seen in ED. Lewis et al [7] reported that dental

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caries, pulp, and periapical infections were the second most frequently listed dental diagnoses, accounting for 43% of discharge diagnoses assigned to ED visits for dental complaints. The treatment of a dental abscess in the ED usually includes incision and drainage (I & D) and antibiotics. However, clinical criteria alone are not always adequate to differentiate patients with dental abscess from simple pulpitis. The criterion standard for diagnosis of a dental abscess remains the collection of pus from the abscess through I & D. Panorex x-rays are traditionally used in the ED evaluation of these patients to detect a dental abscess [8]. Patients need to go to the radiology department for the x- rays, and a radiologist needs to interpret the films. This process is time consuming and impacts ED patient turnover. Other than the presence of an abscess, additional information obtained from x-rays is generally not relevant to ED management because treatment is limited to I & D.

Ultrasound (US) is a rapid and sensitive technique for detecting an abscess [9]. Bedside US is being increasingly used by ED physicians for a variety of applications [10]. The portability, accuracy, and noninvasive features of US make it an ideal tool for use at bedside in the ED. Prior studies have shown that emergency physicians are very accurate in differentiating cellulitis and abscess using bedside US [11]. Bedside US can potentially help emergency physicians detect a dental abscess and decide whether to perform I & D or manage with antibiotics and other conservative measures. To our knowledge, the utility of bedside US in diagnosing a dental abscess in ED has not been previously investigated. The objective of this study was to compare bedside US and panorex radiogra- phy in the diagnosis of a dental abscess in ED.

Methods

A retrospective review of ED patient records was conducted in a level 1 academic, urban ED with an annual census of 48,000. This study was approved by the institutional review board. The ED has an emergency medicine residency and an active US education program. Hospital-based credentialing in emergency US was available and was based on American College of Emergency Physicians US guidelines [12]. Every US examination performed in the ED was recorded on the US system hard drive for quality assurance review, and US findings were logged separately in a log book. In the ED, patients were assessed by both an emergency medicine resident and an attending physician.

Patients were included in the study if they presented with facial pain, swelling, or toothache; had no history of trauma; and received a panorex x-ray and bedside soft tissue US for suspected dental abscess. ultrasound examinations included in this study were performed by 2 emergency medicine physicians who were credentialed by

the hospital to perform bedside US. Both emergency physician sonologists performed US examinations as part of their Patient evaluation. They had previously taken a standardized 16-hour course on emergency ultrasonogra- phy that included didactics and hands-on training sessions. Both physicians had at least 3 years of US experience in the ED, and each had performed at least 100 soft tissue US examinations before the study period.

All patients included in the study underwent a physical examination by an emergency medicine resident and attending physician. The bedside US examinations were performed by the emergency physician sonologists after clinical evaluation. The bedside soft tissue US examinations were performed using either a Phillips EnVisor system (Bothell, WA) with a 5-12 MHz broadband linear transducer or a SonoSite M-Turbo (Bothell, WA) with a 5-10 MHz linear transducer. The US examinations were performed with the patient sitting upright (Fig. 1). The affected areas of face, adjacent normal skin, and Soft tissues were scanned in 2 orthogonal planes. Ultrasound examination of the contralat- eral side was also performed for comparison. Color Doppler was used as necessary to evaluate the soft tissues and adjacent structures. Any abnormal fluid collection was assessed for internal echoes, septations, and posterior acoustic enhancement and compressed to visualize motion of the contents. An abscess was defined as an irregular or round, localized, compressible, anechoic or hypoechoic fluid collection with variable amounts of internal echoes. Cellu- litis was defined as increased echogenicity of skin and subcutaneous tissues or hypoechoic or anechoic strands traversing the subcutaneous tissue or cobblestone appearance of the subcutaneous tissues [13,14]. Figs. 2 and 3 show US findings of a dental abscess.

Panorex x-rays were performed after bedside US examinations because bedside US was readily available in our ED and panorex x-ray required transporting the patient to radiology suite. Both panorex x-rays and US

Fig. 1 patient positioning and transducer placement for facial swelling imaging.

Fig. 2 Ultrasound image of a dental abscess showing irregular anechoic areas (arrows) in a heterogeneous hypoechoic mass.

interpretations were independently reported. The final US interpretation was made at bedside by the emergency physician sonologist before panorex x-rays were performed. The radiologist interpreting the panorex x-rays was not aware of the US findings. The treating emergency physician was aware of the US findings. The decision to obtain dentistry or ENT consult was at the discretion of the emergency physician involved in the care of the patient.

Dentistry or ENT consultants evaluated patient when requested by the treating emergency physicians.

Data extraction was performed using a standardized data extraction form that included information about US findings, final US interpretation, panorex X-ray findings, ED evalu- ation, disposition, final diagnosis, and repeated ED visits. Emergency department US logs were reviewed initially for soft tissue US examinations performed for dental symptoms.

Fig. 3 As compared with the contralateral normal side (left), ultrasound of the right side of the face shows anechoic fluid collection (arrows) consistent with an abscess.

Panorex x-ray reports were reviewed for findings of periapical abscess. Medical records were then reviewed for history, physical examination findings, laboratory results, additional diagnostic testing, disposition, final diagnosis, and repeated ED visits. The bedside US images of all patients included in this study were additionally reviewed for accuracy by an emergency physician sonologist who was blinded to the study hypothesis, ED US interpretations, and other clinical information.

    1. Statistical analysis

Descriptive analyses were performed using SAS version

9.2 (SAS, Cary, NC). Continuous data were presented as means with standard deviations, and dichotomous data were presented as percentage frequency of occurrence. Sensitivity and specificity of US and panorex x-rays were calculated to determine the clinical utility of the 2 tests.

Results

A total of 19 patients (female, 11; male, 8) were identified over a 2-year period. None of the patients were excluded from analysis. The mean age of the patients was 40 years (SD, 13.6). All patients had facial pain, swelling, and localized tenderness of teeth. None of the 19 patients reported recent trauma. Information regarding prior ED visits and recent antibiotic use was not obtained because of inconsistencies in documentation. Thirteen patients (68%) presented with mandibular teeth symptoms and 6 (31%) with maxillary teeth symptoms. Nine patients were evaluated by dentistry or otorhinolaryngology service in the ED upon emergency physician request.

No periapical abscess was reported on panorex x-rays in 7 (37%) of 19 patients. Ultrasound agreed with panorex x-rays in 6 (86%) of 7 cases. One case where US disagreed with x- rays was seen by dentistry consultants; and I & D were performed, confirming the presence of abscess. One patient with no findings of dental abscess on US as well as x-ray was also seen by dentistry service for a salivary gland calculus. No follow-up information was available on patients in whom US and panorex x-rays agreed that there was no abscess. An x-ray diagnosis of periapical abscess was made in 12 (63%) patients. Ultrasound agreed with panorex x-ray in 10 (83%) of 12 cases. Seven of these patients had I & D performed in ED by dentistry or otorhinolaryngology service. One patient declined I & D and was discharged with antibiotics. Two patients were instructed to follow up with dentistry service the next day by the treating ED physician because the abscesses were small. Both patients received antibiotics. In 1 of the 2 cases where US disagreed with panorex x-ray findings, x-ray abnormalities were reported on the opposite side in the mandibular area where the patient did not have any symptoms. Ultrasound of the contralateral mandibular

area was not performed in this case because the patient presented with maxillary symptoms. The other patient was given antibiotics and recommended outpatient follow-up with dentistry service by the treating ED physician. Follow- up information was not available to confirm the presence of an abscess.

Assuming that the patient who was lost to follow-up had dental abscess, the sensitivity and specificity of US in diagnosing a dental abscess were 92% and 100%, respec- tively. Positive predictive value of the US in diagnosing a dental abscess was 100%, and negative predictive value was 88%. Excluding 1 patient who was lost to follow-up from analyses resulted in 100% sensitivity and 100% specificity of US in diagnosing a dental abscess (positive and negative predictive values were 100% each).

None of our study patients were admitted to the hospital. No return ED visits within 1 week were identified on chart review. The average time to perform a bedside US examination was approximately 7 minutes. There was a 100% agreement between emergency physician investigator and blinded sonologist US interpretations.

Discussion

Dental pain is a significant Public health problem in United States, affecting approximately 22 million people during any 6- month period [15]. The incidence of dental symptoms among patients presenting to the ED has been consistently increasing nationwide [16,17]. Increasing health care costs and lack of a regular source of dental care have been associated with increasing ED use for dental problems. The ED has become the final alternative for patients with dental-related complaints and no access to traditional dental services.

Dental problems such as Dental Caries, periodontal disease, pulpitis, and periapical abscess are commonly seen in the ED. Periapical abscess is one of the most common odontogenic infections seen in the ED. Analysis of the distribution of codes associated with physician claims linked to ED claims showed that approximately 28% of claims were related to periapical abscess [18]. A periapical abscess is characterized by pain, swelling, and percussion tenderness of tooth. In the ED, periapical abscess generally requires I & D and antibiotics. A follow-up with a dentist is recommended for definitive therapy that includes removal of the necrotic pulp tissue and restoration or extraction of the tooth [19]. The diagnosis of periapical abscess, however, is not always clear clinically.

Panorex x-rays are often obtained to evaluate patients with suspected dental abscess in the ED [8]. A panorex radiograph provides a view of the entire maxillomandibular region on a single film [20]. It can detect an occult fracture, abscess, the tooth involved, and surrounding bone in the infectious process. A panorex x-ray can reveal Pathologic changes that might be missed during clinical examination [21]. However,

it requires patient leaving the ED to obtain the x-rays and additional time for a radiologist to interpret the x-rays. This adds a delay to the patient care and disposition in ED. dental extraction is not routinely performed in the ED, and management is limited to performing an I & D. Panorex x- rays are primarily used to determine if a patient has an abscess and requires I & D and to select the most appropriate site for the I & D. Additional information provided by panorex x-rays apart from the presence or absence of an abscess does not alter the treatment and disposition of the ED patients.

Ultrasound has been shown to be highly accurate in identifying an abscess [22,23]. It can detect fluid collections well, irrespective of the site [24-26]. Ultrasound can help ascertain the type of infection, cellulitis, or abscess. It can also assist in localizing the site and the extent of soft tissue infection and provide guidance for aspiration and drainage [27]. Over the past 2 decades, emergency physicians have been increasingly using US to help answer important focused clinical questions at the bedside [28-30]. Bedside US has proven to be very useful in evaluating soft tissue infections in the ED. Prior ED studies have demonstrated that bedside US is superior to clinical assessment in determining the presence of a drainable fluid collection [31,32].

To our knowledge, no prior studies have examined the role of US in the evaluation of patients with suspected dental abscess in the ED. Our study supports a potential role of bedside US in the evaluation of patients with suspected dental abscess in the ED setting. Emergency department physicians can use US to detect a dental abscess and decide whether to perform I & D or manage with antibiotics and other conservative measures. The high specificity of US indicates that a positive US finding can be regarded as an evidence of dental abscess. Ultrasound revealed a dental abscess in all cases where I & D were performed by dentistry or otorhinolaryngology service, in contrast to panorex x-ray where an abscess was not seen in one of the patients. In our study, US was more reliable than panorex x-ray in the evaluation of patients with suspected dental abscess.

Recently, EDs have seen a huge surge in the use of computed tomography (CT) for a variety of indications. Dental pain and abscess are no exception; and in some facilities, it may be easier to order a facial CT than a panorex x-ray when a dental or facial abscess is suspected. This trend is driven by the ease of use of CT, requiring much less additional skill on the part of a technician. However, a variety of protocols and disagreement about indications and technique exist [33]. In addition, recent awareness of high radiation exposure and overuse of CT has called into question the temptation to order a CT scan [34]. Furthermore, with our nation’s health care system under tremendous financial pressure, less expensive alternatives to CT should be considered whenever possible. Ultrasound is a simple, rapid, inexpensive, and readily available imaging technique in ED. It does not involve the use of ionizing radiation and can be performed bedside.

Ultrasound examinations can be performed right after clinical assessment, which can lead to early diagnosis, appropriate consultation, and therapy. We were unable to accurately determine the time taken to complete a panorex x-ray examination and obtain a radiologist report. Based on our results, we recommend using US for ED evaluation and management of patients with suspected dental abscess and recommend follow-up with a dentist for definitive management. We advocate this approach because the additional information provided by panorex x-ray does not alter the management of these patients in ED. Active use of US would decrease the need for radiological imaging and allows for a faster patient disposition and improvED throughput during demanding hours in ED.

Our study had several limitations, including its retrospective nature. The data collectors were not blinded to the study hypothesis. We attempted to minimize the bias associated with retrospective data collection by using a standardized abstraction form. No specific ED protocol to evaluate dental pain or facial swelling was followed during the study period. Not all patients who received a panorex x-ray for suspected dental abscess were included in the study because a bedside US was not performed in all these cases. Patients received bedside US only when credentialed Emergency sonologists were on duty, and these patients were included in our study. In addition, not all patients who received a bedside US for suspected dental abscess received a panorex x-ray. It is also possible that some patients suspected of having a dental abscess were empirically treated with antibiotics and did not receive an US or a panorex x-ray. All these factors could have led to a selection bias.

The information regarding the total number of patients with dental symptoms who received a panorex x-ray for suspected dental abscess and overall incidence of dental abscess in our ED during the study period was not available to the study investigators. Not all patients diagnosed with a dental abscess in our study underwent I & D because a dentistry or otorhinolaryngology service consultation was not obtained for all patients. The diagnosis of a dental abscess was not confirmed with I &D in all cases. The ED US findings, however, have been confirmed for accuracy by another blinded sonologist. In addition, medical records of all our study patients have been reviewed for any return ED visits; and subsequent changes in patient management were compared with management during the initial ED visit. Information from dentistry follow-up visit was not available to study investigators. There was no analysis of time to diagnosis, treatment, and disposition of our study patients. Hence, no definite conclusions can be drawn with respect to differences in these outcomes between US and panorex x-ray. Our study physicians may have more scanning experience compared with an average emergency physician sonographer. These limitations and small sample size of our study need to be taken into consideration. A large

prospective study that includes all patients with facial swelling or toothache is needed to clearly define the role of bedside ED US in the diagnosis of a dental abscess.

Despite limited sample size, our study suggested that bedside US is useful in the diagnosis of a dental abscess in the ED. Bedside US is a rapid, inexpensive, and nonionizing imaging modality that can provide an alternative to panorex x-rays in the evaluation of patients with suspected dental abscess and potentially improve throughput in the ED.

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