Diagnostic Validity of Urinalysis in Comparison with Urine Culture Prior to Micturating Cystourethrogram in Children: A Retrospective Observational Study at a Tertiary Care Centre in Kerala, India

Abstract

Introduction: Micturating Cystourethrogram (MCUG)-triggered Urinary Tract Infections (UTIs) are well-known, but the risk factors that trigger infections are not well studied. Even though MCUG being invasive, there is no general consensus regarding the use of peri-procedural antibiotic coverage and screening for sub-clinical UTIs just before MCUG. Aim: To determine the diagnostic validity of Urinalysis (UA) when compared with the gold standard, Urine Culture and Sensitivity (UCS), to exclude pre-procedure infections. Materials and Methods: This retrospective observational study involved paediatric patients who underwent MCUG from January 2021 to December 2022, at Kozhikode Government Medical College (Kerala) to exclude urological anomalies. All children were tested with UA and UCS before MCUG, which was done under antibiotic coverage. A positive UCS was defined as a significant growth of a single organism (>100,000 for mid-stream urine or >50,000 for catheterised sample), while a positive UA was defined as pus cells >5/high power field on microscopy. After exclusions, the authors analysed 300 patients. The diagnostic validity of UA was assessed using the Pearson Chi-square test, by Statistical Package for Social Sciences (SPSS) version 16.0. and a p-value less than 0.05 was considered significant. Results: The median age was nine months (IQR 13 months) with 68% being male. The most common indication for MCUG was evaluation for recurrent/febrile UTIs (n=171, 56.6%). Both Pre-MCUG, UA and UCS were documented as positive in eight patients (2.6%), and pre-MCUG, UCS alone was positive in two patients. The diagnostic validity of UA when compared with UCS showed high specificity and positive predictive values at 100% (p<0.05). Conclusion: A simple UA, when compared with UCS (the gold standard investigation for UTIs), has high specificity and positive predictive value in excluding sub-clinical UTIs prior to MCUGs. It may be preferable as it yields quick and reliable results.