Prevalence of microhematuria in renal colic and urolithiasis: a systematic review and meta-analysis

BACKGROUND: This systematic review and meta-analysis aims to investigate the prevalence of microhematuria in patients presenting with suspected acute renal colic and/or confirmed urolithiasis at the emergency department. METHODS: A comprehensive literature search was conducted to find relevant data on prevalence of microhematuria in patients with suspected acute renal colic and/or confirmed urolithiasis. Data from each study regarding study design, patient characteristics and prevalence of microhematuria were retrieved. A random effect-model was used for the pooled analyses. RESULTS: Forty-nine articles including 15'860 patients were selected through the literature search. The pooled microhematuria prevalence was 77% (95%CI: 73-80%) and 84% (95%CI: 80-87%) for suspected acute renal colic and confirmed urolithiasis, respectively. This proportion was much higher when the dipstick was used as diagnostic test (80 and 90% for acute renal colic and urolithiasis, respectively) compared to the microscopic urinalysis (74 and 78% for acute renal colic and urolithiasis, respectively). CONCLUSIONS: This meta-analysis revealed a high prevalence of microhematuria in patients with acute renal colic (77%), including those with confirmed urolithiasis (84%). Intending this prevalence as sensitivity, we reached moderate values, which make microhematuria alone a poor diagnostic test for acute renal colic or urolithiasis. Microhematuria could possibly still important to assess the risk in patients with renal colic.