Diagnostic Imaging in the Evaluation of Asymptomatic Microhematuria: Systematic Review and Meta-analysis

Microhematuria is a highly prevalent condition with a low associated risk of urothelial and upper tract malignancy. The AUA Guidelines recently changed recommendations for imaging favoring renal ultrasound for low- and intermediate-risk patients with microhematuria. We summarize the diagnostic test characteristics of computed tomography urography, renal ultrasound, and magnetic resonance urography in comparison with surgical pathology for the diagnosis of upper urinary tract cancer in microhematuria and gross hematuria patients.

This study is a systematic review and meta-analysis using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines from evidence collected for the 2020 AUA Microhematuria Guidelines report, including studies assessing imaging following diagnosis of hematuria published from January 2010 through December 2019.

The search identified 20 studies which reported the prevalence of malignant and benign diagnoses in relation to imaging modality, of which 6 were included in the quantitative analysis. For the detection of renal cell carcinoma and upper urinary tract carcinoma in patients with microhematuria and gross hematuria, computed tomography urography had a sensitivity of 94% (95% CI, 84%-98%) and a specificity of 99% (95%CI, 97%-100%) with a certainty of evidence rating of very low and low, respectively when 4 studies were pooled. In comparison, ultrasound demonstrated a sensitivity ranging from 14%-96% (low certainty of evidence) and a specificity of 99%-100% in 2 studies (moderate certainty of evidence), while magnetic resonance urography demonstrated a sensitivity of 83% and specificity of 86% in 1 study with a low certainty of evidence.

In a limited data set for each individual imaging modality, computed tomography urography appears the most sensitive imaging modality for the diagnostic evaluation of microhematuria. Future studies will be needed to evaluate the clinical and health system financial impacts of the change in guideline recommendations from computed tomography urography to renal ultrasound in evaluating low- and intermediate-risk patients with microhematuria.