Diagnostic efficacy of computed tomography of the urinary tract for suspected acute urolithiasis

Abstract

Introduction: Multi-Detector Computed Tomography (MDCT) is the gold standard for investigating suspected acute urolithiasis. Unenhanced Computed Tomography of the kidneys ureters and bladder (UECT KUB), performed for suspected urolithiasis, have high detection rates for uroliths and non-urolithiasis related pathology. Technique variations during UECT may sometimes prove beneficial to the patient management process. Evaluation of the efficacy of a current radiographic imaging protocol may substantiate the need for a protocol and allow for improved patient management. Objectives: The main aim of the study was to evaluate the effectiveness of an imaging protocol for suspected acute urolithiasis on three levels of efficacy. The objectives of this research were to firstly investigate the detection rate of urolithiasis as a parameter of diagnostic accuracy efficacy (DAE). Secondly to evaluate the detection rate of non-urology pathology as a parameter of diagnostic thinking efficacy (DTE) and thirdly to determine the contribution of UECT to the patient management process as a parameter of therapeutic efficacy (TPE). Methods: A retrospective cross-sectional study was conducted at a private hospital in the Cape metropole by collecting data from the Picture Archiving and Communication System (PACS). Records from 01 January 2010 up to and including 31 December 2017 of 753 patients, referred for suspicion of acute urolithiasis were reviewed. A total of 449 records that matched the inclusion criteria were analysed. Records indicating urolithiasis were separated from records indicating non-urolithiasis related pathology for measurement of DAE and DTE. Records indicating urology intervention were grouped for measurement of TPE. Characteristics of grouped records were assessed to explain DAE, DTE and TPE outcomes. Results: The total number of positive cases for urolithiasis during UECT KUB was 35% (n=159). From the sample, 16% (n=113) of records indicated non-urolithiasis related pathology. Gastrointestinal pathology accounted for the highest incidence at 32% (n=37) with other urinary tract pathology following at 28% (n=32). Urologic intervention was indicated in 46% (n=201) of patients identified with urolithiasis. Conclusion: The urolith amount and size were found to increase intervention rates. Urolith size larger than 5mm was a determining factor that influenced the therapeutic rate for urolithiasis at the study site. It is recommended that the current protocol of prone rescanning is not indicated in cases where urolith size is < 5mm as intervention rates are not influenced by the scanning position. In cases where UECT KUB excluded urolithiasis, other pathologies were detected for further medical referral. The imaging protocol currently used at the research site is optimal for diagnosing the presence and magnitude of urolithiasis and for providing a management pathway for patients.