Engagement of sonographers performing pediatric appendiceal ultrasound through training in the scanning technique and awareness of secondary signs significantly improved the visualization rate and provided more meaningful findings to referrers.
Sonography is an important clinical tool in diagnosing appendicitis in children as it can obviate both exposure to potentially harmful ionising radiation from computed tomography scans and the need for unnecessary appendicectomies. This review examines the diagnostic accuracy of ultrasound in the identification of acute appendicitis, with a particular focus on the the utility of secondary sonographic signs as an adjunct or corollary to traditionally examined criteria. These secondary signs can be important in cases where the appendix cannot be identified with ultrasound and a more meaningful finding may be made by incorporating the presence or absence of secondary sonographic signs. There is evidence that integrating these secondary signs into the final ultrasound diagnosis can improve the utility of ultrasound in cases where appendicitis is expected, though there remains some conjecture about whether they play a more important role in negative or positive prediction in the absence of an identifiable appendix.
Introduction: Ultrasound is commonly used as a tool for investigation of acute appendicitis in children. The accuracy of ultrasound in appendicitis depends on the ability to visualise the appendix and the potential contribution from secondary signs. The study was a retrospective analysis of children referred for sonographic investigation of possible acute appendicitis at an Australian Methods: Radiology reports, ultrasound images and electronic medical records were evaluated for eligible patients. The ability to visualise the appendix and determine secondary sonographic signs was evaluated for diagnostic accuracy.Results: The study identified 457 eligible children, with the appendix visualised on ultrasound in 40.7% of cases. Using a binary diagnostic model that incorporated equivocal results, sensitivity of ultrasound to diagnose acute appendicitis was 88.1%, specificity 91.4% and accuracy 90.4%. Ultrasound was found to have a high negative predictive value (96.3%), and the presence of echogenic mesentery had a positive predictive value of 89.4%.
Discussion:Our results compare favourably with other studies, but indicate the potential for improvement in accuracy and visualisation, with a future study incorporating new methods of categorising ultrasound findings currently being undertaken.Funding: This manuscript is based on research performed as part of a higher research degree at Queensland University of Technology (QUT), Brisbane, Australia. Conflict of interest: None.Sonography 3 87-94
Introduction
We evaluated the predictive value of sonographic and clinical variables in the diagnosis of acute appendicitis in children using decision tree modelling.
Methods
Data pooled from two prior studies in the same population of children referred for ultrasound examination of suspected acute appendicitis. Ultrasound and clinical variables were collated and compared with patient records. Decision tree algorithms were used to model data to identify highly discriminatory variables. Receiver operative characteristic (ROC) curve analyses were performed on different models of appendiceal diameter criteria.
Results
There were 687 examinations included. Diameter modelling indicated that categorical assessment – below 6 mm as negative, diameters between 6 and 8 mm equivocal for appendicitis and above 8 mm positive – was more accurate (AUROC = 0.921) than the most accurate binary cut‐off (7 mm, AUROC = 0.886). Decision tree analysis supported categorical diameter criteria, demonstrated that the presence of echogenic mesentery was an important variable and showed that common blood test results can be complementary discriminators of ultrasound findings.
Discussion
The use of a binary appendiceal diameter cut‐off was less accurate than a three‐category model. Absence of peri‐appendiceal mesentery inflammation is an important negative predictor of appendicitis in children, even without direct visualisation of the appendix.
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