ATLANTA—Microscopic hematuria is an unreliable indicator of urinary tract malignancy, according to study findings presented at the American Urological Association 2012 annual meeting.

The most reliable indicators are age 50 and older and a prior history of gross hematuria, said lead investigator Ronald Loo, MD, of Kaiser Permanente Downey Medical Center, who presented the findings. Asymptomatic patients with microhematuria who are younger than 50 and have no history of gross hematuria may require no workup at all, he said.

The findings are based on a cohort study of 4,414 patients enrolled from January 2009 to August 2011 based on AUA Best Practice Recommendations: two of three urinalysis results with greater than 3 rbc/hpf. Upper urinary tract imaging consisted of multiphase computed tomography (CT) or intravenous pyelogram and renal ultrasound. All subjects underwent cystoscopy.

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The overall urinary tract cancer detection rate was 2.1%, with patients older than 50 with a history of gross hematuria at greatest risk for being diagnosed with a urinary tract cancer. A history of smoking and male gender was less predictive, and the degree of hematuria (greater than 25 rbc/hpf) was the least predictive.

“CT may not be the most appropriate imaging modality to utilize in initially screening hematuria patients because of the incredibly low yield in detecting renal malignancy and high radiation exposure,” Dr. Loo told colleagues. “A more effective means of screening for bladder cancer is asymptomatic patients may be to convince our primary care colleagues to stop ordering a screening urinalysis and start asking about gross hematuria,” he told colleagues.