Asymptomatic Microhematuria Guidelines Released by AUA

Joe Barber Jr, PhD

October 26, 2012

In a revision of its previous "best practice" document, the American Urological Association (AUA) has released new guidelines for diagnosing, evaluating, imaging, and following up asymptomatic microhematuria in adults.

These guidelines were presented by Rodney Davis, MD, from Vanderbilt University Hospital in Nashville, Tennessee, and colleagues in an article published online October 23 and in the December print issue of the Journal of Urology.

The authors reviewed the literature to identify studies published between January 1980 and November 2011 that were "relevant to the diagnostic yield of mass screening for microhematuria and the work-up and follow-up of adult patients with [asymptomatic microhematuria]."

In the guideline, asymptomatic microhematuria is defined as 3 or more red blood cells per high-powered field "on a properly collected urine specimen in the absence of an obvious benign cause." Diagnosis of asymptomatic microhematuria is not based on dipstick results.

Patients with asymptomatic microhematuria should undergo assessments including a careful history, laboratory examination, and physical examination to rule out benign causes of asymptomatic microhematuria, including infection, menstruation, vigorous exercise, medical renal disease, viral illness, trauma, or recent urological procedures. A urologic evaluation should be undertaken once potential benign causes have been disproven, and renal function assessment should be part of the initial evaluation.

Asymptomatic microhematuria in the setting of anticoagulation use still requires evaluation and work up for the underlying cause. In addition, the authors write in guideline 5, "The presence of dysmorphic [red blood cells], proteinuria, cellular casts and/or renal insufficiency or any other clinical indicator suspicious for renal parenchymal disease warrants concurrent nephrologic work-up but does not preclude the need for urologic evaluation."

A major change in the guideline was the recommendation of cystoscopy for all patients aged 35 years or older. In the previous guideline, cystoscopy was recommended for patients aged 40 years or older.

Cystoscopy is also recommended for patients who present with risk factors for urinary tract malignancies, including symptoms of irritative voiding, chemical exposures, and history of smoking. Among patients younger than 35 years, cystoscopy can be performed at the discretion of the physician.

Radiologic and other imaging modalities are also recommended as a part of the diagnosis. Alternative imaging protocols were identified for patients who were unsuitable for certain procedures, such as magnetic resonance urography for patients who cannot undergo multiphasic computed tomography.

Alternatively, the use of urine cytology and urine markers, such as NMP22 for bladder cancer, as well as blue light cystoscopy are not recommended for evaluating patients with asymptomatic microhematuria. No further urinalyses are needed for patients with 2 consecutive negative annual urinalyses, whereas annual urinalyses are recommended in cases of persistent asymptomatic microhematuria.

Guidelines May "Spur Unnecessary Testing"

Robert A. Cohen, MD, from Beth Israel Deaconess Medical Center in Boston, Massachusetts, suggested that the revised guidelines were flawed. "The authors advise cystoscopy in everyone 35 years and older with [asymptomatic microhematuria]," Dr. Cohen told Medscape Medical News by email. "This change is done without any supportive data."

"They are honest about the very poor quality of the AUA guideline — only based on grade C evidence (and questionable use of this evidence as it applies to cystoscopy in individuals a younger age) and expert opinion. On the whole, I believe these guidelines will spur much unnecessary invasive testing."

Funding for the Practice Guideline Committee was provided by the AUA. Dr. Davis reports acting as a consultant for the Corrections Corp of America. Full conflict-of-interest information is available in the article. Dr. Cohen has disclosed no relevant financial relationships.

J Urol. 2012;188:2473-2481. Abstract

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