An Interdisciplinary Initiative to Reduce Radiation Exposure: Evaluation of Appendicitis in a Pediatric Emergency Department With Clinical Assessment Supported by a Staged Ultrasound and Computed Tomography Pathway

Abstract

Objectives: In the emergency department (ED), a significant amount of radiation exposure is due to computed tomography (CT) scans performed for the diagnosis of appendicitis. Children are at increased risk of developing cancer from low-dose radiation and it is therefore desirable to utilize CT only when appropriate. Ultrasonography (US) eliminates radiation but has sensitivity inferior to that of CT. We describe an interdisciplinary initiative to use a staged US and CT pathway to maximize diagnostic accuracy while minimizing radiation exposure.Methods: This was a retrospective outcomes analysis of patients presenting after hours for suspected appendicitis at an academic children's hospital ED over a 6-year period. The pathway established US as the initial imaging modality. CT was recommended only if US was equivocal. Clinical and pathologic outcomes from ED diagnosis and disposition, histopathology and return visits, were correlated with the US and CT. ED diagnosis and disposition, pathology, and return visits were used to determine outcome.Results: A total of 680 patients met the study criteria. A total of 407 patients (60%) followed the pathway. Two-hundred of these (49%) were managed definitively without CT. A total of 106 patients (26%) had a positive US for appendicitis; 94 (23%) had a negative US. A total of 207 patients had equivocal US with follow-up CT. A total of 144 patients went to the operating room (OR); 10 patients (7%) had negative appendectomies. One case of appendicitis was missed (<0.5%). The sensitivity, specificity, negative predictive value, and positive predictive values of our staged US-CT pathway were 99%, 91%, 99%, and 85%, respectively. A total of 228 of 680 patients (34%) had an equivocal US with no follow-up CT. Of these patients, 10 (4%) went to the OR with one negative appendectomy. A total of 218 patients (32%) were observed clinically without complications. Conclusions:Half of the patients who were treated using this pathway were managed with definitive US alone with an acceptable negative appendectomy rate (7%) and a missed appendicitis rate of less than 0.5%. Visualization of a normal appendix (negative US) was sufficient to obviate the need for a CT in the authors' experience. Emergency physicians (EPs) used an equivocal US in conjunction with clinical assessment to care for one-third of study patients without a CT and with no known cases of missed appendicitis. These data suggest that by employing US first on all children needing diagnostic imaging for diagnosis of acute appendicitis, radiation exposure may be substantially decreased without a decrease in safety or efficacy.

Properties of Serial Ultrasound Clinical Diagnostic Pathway in Suspected Appendicitis and Related Computed Tomography Use

“…[1][2][3][4][5][6] Despite its advantages, 7 ultrasound (US) by itself has limited diagnostic utility for suspected appendicitis, 8 with the rate of equivocal examinations in some studies approaching 50%. [9][10][11][12] Several scoring systems, including the pediatric appendicitis score (PAS), 13 also do not perform well in isolation at diagnosing appendicitis. [14][15][16][17][18][19][20][21] An intravenous contrast-enhanced computed tomography (CT) scan is currently recommended in children with equivocal screening US results.…”

Editorial

“…The sensitivity, specificity, NPV, and PPV of the staged US-CT pathway were 99%, 91%, 99%, and 85%, respectively. Visualization of a normal appendix (negative US) was sufficient to obviate the need for a CT [10]. This data suggests that by employing US first in all children who need diagnostic imaging, radiation exposure may be substantially decreased without decreasing safety or efficacy.…”

“…Significantly, for equivocal US findings, the acute appendicits frequency was 44%, while for clear evidence of non-perforated or perforated acute appendicits, the frequency was 92.3% and 100%, respectively [9]. Ultrasound eliminates radiation but has sensitivity inferior to CT [10]. Ramarajan, et al [10] described a staged US and CT pathway in which US was the initial imaging modality and CT was recommended only if US was equivocal.…”

“…Ultrasound eliminates radiation but has sensitivity inferior to CT [10]. Ramarajan, et al [10] described a staged US and CT pathway in which US was the initial imaging modality and CT was recommended only if US was equivocal. The sensitivity, specificity, NPV, and PPV of the staged US-CT pathway were 99%, 91%, 99%, and 85%, respectively.…”

“…The finding of a normal completely or incompletely visualized appendix can rule out acute appendicits while clear evidence of perforated or nonperforated appendicitis mandates surgery [9]. If the US findings are equivocal, CT scan should be performed in view of its higher sensitivity and PPV [10][11][12]. Especially in resource-deficient countries like India, this would appear to be a safe and cost-effective staged diagnostic protocol.…”