UC San Diego

Asymptomatic microscopic hematuria is an important clinical sign of urinary tract malignancy. Asymptomatic microscopic hematuria has been variably defined over the years. In addition, the evidence primarily is based on data from male patients. However, whether the patient is a man or a woman influences the differential diagnosis of asymptomatic microscopic hematuria, and the risk of urinary tract malignancy (bladder, ureter, and kidney) is significantly less in women than in men. Among women, being older than 60 years, having a history of smoking, and having gross hematuria are the strongest predictors of urologic cancer. In low-risk, never-smoking women younger than 50 years without gross hematuria and with fewer than 25 red blood cells per high-power field, the risk of urinary tract malignancy is less than or equal to 0.5%. Furthermore, the evaluation may result in more harm than benefit and is unlikely to be cost effective. Thus, data support changing current hematuria recommendations in this low-risk group. The American College of Obstetricians and Gynecologists and the American Urogynecologic Society encourage organizations producing future guidelines on the evaluation of microscopic hematuria to perform sex-specific analysis of the data and produce practical sex-specific recommendations. In the meantime, the American College of Obstetricians and Gynecologists and the American Urogynecologic Society recommend that asymptomatic, low-risk, never-smoking women aged 35-50 years undergo evaluation only if they have more than 25 red blood cells per high-power field.