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A positive dipstick test does not define microhematuria, but instead should trigger a formal microscopic urinalysis to seek a definitive diagnosis, according to a new clinical guideline from the American Urological Association (AUA) and the Society of Urodynamics, Female Pelvic Medicine, & Urogenital Reconstruction.

According to the guideline, a diagnosis of microhematuria in adults requires presence of more than three red blood cells per high-power field. Microhematuria can indicate a number of benign conditions but may also represent a more serious underlying condition, including bladder cancer.

"The goal of the new guideline is to provide a risk-stratified approach to hematuria evaluation based on the patient's risk factors for urinary tract cancer," guideline panel co-chair Daniel Barocas, MD, of Vanderbilt University Medical Center in Nashville, said in a statement. "We crafted the guideline with the intention of reducing the intensity of evaluation in those at low risk for malignancy, while preserving the diagnostic sensitivity of evaluation in those at higher risk."

The guideline, available on the , includes 22 recommendations that cover the diagnosis and definition of microhematuria, initial evaluation, risk stratification, urinary markers, and follow-up. Recommendations include the following:

• A positive dipstick alone is not sufficient for a diagnosis of microhematuria
• Initial evaluation should take into account the possibility of genitourinary malignancy, medical renal disease, gynecologic causes, and nonmalignant genitourinary causes of microhematuria
• Use the evaluation to guide risk assessment, which determines next steps, including repeat urinalysis, cystoscopy, renal ultrasound, or axial imaging

The guideline provides risk-assessment criteria to assign patients to one of four risk categories: low, initially low with microhematuria on repeat urinalysis, intermediate, and high. Each risk category delineates next steps, as well as optional steps.

For low-risk patients, the panel recommends discussing the choice between repeat urinalysis in 6 months or proceeding with cystoscopy and renal ultrasound. Patients who opt for repeat urinalysis should be reclassified as intermediate or high risk if the follow-up urinalysis is also positive and undergo cystoscopic examination and upper tract imaging.

For high-risk patients, the guideline panel recommended cystoscopy and axial upper-tract imaging, as well as optional imaging. White light cystoscopy is recommended for evaluation of the bladder, additional imaging of the urinary tract may be considered for patients with persistent or recurrent microhematuria previously evaluated by renal ultrasound.

Patients who have a family history of renal cell carcinoma or a known genetic renal tumor syndrome should undergo upper tract imaging regardless of risk category.

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