Written by Chris Thom
Spoon Feed
This was a single center retrospective study at a tertiary pediatric ED of patients with suspected pediatric appendicitis. The authors found that combining a low pediatric Appendicitis Risk Calculator (pARC) result with a nondiagnostic ultrasound results in a high negative predictive value for appendicitis.
Imaging data should not be used in isolation
This retrospective study was an analysis of three previously conducted prospective trials on suspected pediatric appendicitis that had occurred over the span of 2007-2021. The reference standard was the operative pathology report. 1181 patients were enrolled, 360 of which had appendicitis (30.5%). The authors evaluated the 269 patients with a “low risk” nondiagnostic ultrasound, which was defined as non-visualization of the appendix along with no secondary signs of pathology or inflammation. Twenty-one (7.8%) of these patients had appendicitis. A subset of these 269 patients also had a low-risk pARC < 15% result, with 163 falling into this category. Two of these patients (1.2%, 95% CI 0%-4.4%) had appendicitis.
Low-risk pARC combined with a nondiagnostic ultrasound carried a sensitivity of 96.7% (95%CI 88.5%-99.6%) and negative predictive value of 98.8% (95%CI 95.6%-99.9%). The risk of appendicitis in the setting of a nondiagnostic ultrasound increased as the risk level denoted by the pARC increased.
How will this change my practice?
The suspected pediatric appendicitis patient with a nondiagnostic ultrasound remains a challenge for the emergency physician. While nondiagnostic ultrasound patients with no secondary inflammatory findings are lower risk for appendicitis, this risk can be as high as 8.6% (1). Combining a nondiagnostic ultrasound with lower pretest probability patients is a mechanism to further reduce this rate and target the very low risk population that does not need further ED workup. The current study provides one manner to do this via combination with low risk pARC. Given that clinical gestalt has demonstrated similar results to pediatric clinical decision rules in the past (2,3), one might suspect that the combination of low clinical gestalt with nondiagnostic ultrasound would also yield a very high negative predictive value.
Editor’s note: I’m starting to see a pattern here, we covered a very similar article answering the same question with the Alvarado score and low-risk nondiagnostic ultrasounds. ~Nick Zelt
Source
Identification of children with a nondiagnostic ultrasound at a low appendicitis risk using a pediatric Appendicitis Risk Calculator. Acad Emerg Med. Published online July 21, 2024.
Works Cited
- Kearl YL, Claudius I, Behar S, et al. Accuracy of Magnetic Resonance Imaging and Ultrasound for Appendicitis in Diagnostic and Nondiagnostic Studies. Acad Emerg Med. 2016;23(2):179-185.
- Lee WH, O’Brien S, Skarin D, et al. Accuracy of clinician gestalt in diagnosing appendicitis in children presenting to the emergency department. Emerg Med Australas. 2019;31(4):612-618.
- Simon LE, Kene MV, Warton EM, et al. Diagnostic Performance of Emergency Physician Gestalt for Predicting Acute Appendicitis in Patients Age 5 to 20 Years. Acad Emerg Med. 2020;27(9):821-831.
