Most Referrals of Women for Asymptomatic Microscopic Hematuria Are Inappropriate

By Will Boggs MD

July 15, 2019

NEW YORK (Reuters Health) - More than half of referrals of women for asymptomatic microscopic hematuria are inconsistent with American Urological Association (AUA) guidelines, according to a retrospective study.

"I hope physicians reading this study are encouraged to familiarize themselves with guidelines outside of their own societies in order to equip themselves to take the best care of their patients," Dr. Stephanie J. Handler from Harbor-UCLA Medical Center, in Torrance, California, told Reuters Health by email.

AUA defines asymptomatic microhematuria as three or more red blood cells (RBC) per high-power field (HPF) on a properly collected urinary specimen in the absence of an obvious benign cause (infection, menstruation, vigorous exercise, and so on) and recommends cystoscopy and upper genitourinary tract imaging to evaluate it. Even with a positive microscopic urinalysis, the low-risk woman's risk of any urologic malignancy is estimated to be less than 0.5%.

Dr. Handler's team examined the frequency and estimated the cost of unindicated evaluation for suspected microhematuria in 100 women referred to one of three urologists trained in female pelvic medicine and reconstructive surgery.

Overall, 54 women (54%) were referred for evaluation of asymptomatic microhematuria despite clearly not meeting the AUA definition: 33 were referred based on dipstick-positive results only, 11 were referred based on microscopic urinalysis showing fewer than three RBC/HPF, and 10 were referred based on microhematuria in the setting of a clear benign cause.

Only eight (24%) of the 33 women referred based on dipstick-positive results turned out to have microscopy-proven asymptomatic microhematuria after evaluation by the specialist, the researchers report in the August issue of Obstetrics and Gynecology.

All 10 of the women with a clear benign cause of their microhematuria no longer had microscopy-proven microhematuria at the specialist's office.

Among the 100 women referred, 30 of the 68 (44%) referred by internists and family medicine physicians and 24 of the 32 (75%) referred by obstetrician-gynecologists did not meet AUA criteria for asymptomatic microhematuria.

The average cost of the AUA-indicated workup of the 46 women who actually had urine microscopy-proven asymptomatic microhematuria was $8,299 per patient, and the average cost of the workup in women who did not initially meet AUA criteria was $1,214 per patient.

In 2017, the American College of Obstetricians and Gynecologists (ACOG) and the American Urogynecologic Society jointly published an opinion regarding the diagnosis and evaluation of asymptomatic microhematuria that recommended against workup in asymptomatic women aged 35-50 who have never smoked and are otherwise at low risk for genitourinary malignancy unless there are more than 25 RBC/HPF.

"I think that referral patterns among obstetrician-gynecologists will significantly improve following (these) recommendations," Dr. Handler said. "In my experience, most OB/GYNs pay very close attention to and are adherent with ACOG's recommendations. Anecdotally, I have already noticed an improvement in OB/GYNs' knowledge on asymptomatic microscopic hematuria, including how to work-up this condition and when to refer for this condition."


Obstet Gynecol 2019.