Asymptomatic microhematuria is defined in the guideline as "three or more red blood cells per high-powered field on a properly collected urinary specimen in the absence of an obvious benign cause" (eg, infection, trauma, or renal disease) and may indicate more serious conditions.
The new guideline suggests that a single positive urinalysis with microscopy for asymptomatic microhematuria is enough to warrant a complete urologic examination. This guidance updates previous recommendations, issued in 2001, which stated that a full exam be completed only after 2 of 3 properly collected samples test positive for microhematuria on microscopy.
A urologic malignancy will be diagnosed in only a small subset of patients with microhematuria, the AUA states in a written release; however, benign conditions that can cause microhematuria, such as stricture and stone disease, can benefit from active clinical management or follow up.
"Urinary tract conditions that cause bleeding are often 'silent' and present with few symptoms until the disease is advanced or causes more serious symptoms," said panel chair Rodney Davis, MD, from the Vanderbilt University Medical Center in Nashville, Tennessee. "For most patients, microhematuria may be the earliest warning to health care providers of urinary tract disease, so it is important that we evaluate these patients to prevent serious problems later."