Accuracy of ultrasonography and computed tomography in the diagnosis of acute appendicitis

Abstract

Background: Acute appendicitis (AA) is a common reason for surgical intervention. Considering the high burden of AA, early and correct diagnosis is crucial. Two imaging modalities (i.e., ultrasonography and computed tomography) are frequently used for the diagnostic evaluation of AA. However, there is lack of clarity regarding their diagnostic accuracy. Choosing the most valid intervention to diagnose AA would have important clinical implications. Aim of Study: To assess the diagnostic accuracy of ultrasonography (US) and computed tomography (CT) in the diagnosis of AA in adolescents and adults. Methods: This structured literature review (SLR) was carried out using the components of the PICO framework. The literature search was conducted using Cochrane, Embase and PubMed databases. All steps in the SLR were followed, from searching for relevant studies to selecting them, extracting their data, assessing their quality, and synthesising their results. Results of the search process were recorded according to the Preferred Reporting Items for Systematic reviews and Meta-analyses (PRISMA) flow diagram. This SLR included studies on adolescents and adult patients (aged >14 years) with confirmed AA, that were diagnosed using both US and CT. Articles published before 2012, those published in languages other than English, or with no available full text were excluded. The quality assessment of the selected articles was done using the Critical Appraisal Skills Programme (CASP) checklist. Results: Five articles were included in this SLR. The highest reported sensitivity for US was 98.5%, while the lowest was 58.2%. The highest specificity of US was 97.3%, while the lowest was 54.2%. High diagnostic accuracy rates of US were reported by the included studies ranging from 83% and 93.14%. All included studies reported that CT had very high sensitivity for the diagnosis of AA, reaching 100% in one study, while slightly lower sensitivity rates were reported by other studies ranging from 96% to 98.9%. The specificity of CT was reported to be 100% by two studies, while other high specificity rates were reported by three studies (i.e., 97.2%, 89% and 88.9%). The diagnostic accuracy for CT was consistently higher than that of US. Conclusions and implications: The diagnostic accuracy of CT is higher than that of US. However, CT cannot be routinely used because of its high cost and the associated potentially harmful effects of ionizing radiation. Therefore, it is recommended that in cases clinically suspected to be AA, US can be used as the first-line diagnostic modality, followed by CT when the results of US are not conclusive. Keyword: Ultrasonography, Computed tomography, Acute appendicitis, Diagnostic Accuracy, Sensitivity, Specificity, Predictive Value, Validity.