What To Do About Microscopic Hematuria

Abstract & Commentary

By Frank W. Ling, MD, Clinical Professor, Department of Obstetrics and Gynecology, Vanderbilt University School of Medicine, Nashville, is Associate Editor for OB/GYN Clinical Alert.

Dr. Ling reports no financial relationship to this field of study.

Synopsis: Three or more red cells per high power field in two of three clean-catch midstream urine specimens warrants consideration of further evaluation to include urine cytology, cystoscopy, and upper tract imaging.

Source: Erekson EA, et al. Microscopic hematuria in women. Obstet Gynecol 2011;117:1429-1434.

This case-driven discussion of microscopic hematuria includes important guidelines, definitions, and reminders to aid the clinician in managing this common finding. The definition of 3 rbc/hpf on two of three clean-catch midstream samples comes from the American Urological Association and minimizes the unnecessary work-up of transient causes of microscopic hematuria including menstrual contamination, vigorous exercise, intercourse, or trauma. Urine dipsticks can show false-positive results because of hemoglobin, myoglobin, or povidone-iodine. True positives are classified into renal, extrarenal, urogenital, and other sources. The most common etiologies in women are cystitis and calculi. Although uncommon, bladder cancer, which has 1.4 new cases/100,000 annually, is a more common cause of death than cervical cancer. High-risk factors include age over 40, history of pelvic radiation, history of exposure to dyes and chemicals, smoking, analgesic abuse, and history of gross hematuria.

Commentary

I bet you didn't know that bladder cancer is the cause of more deaths in women than cervical cancer. We face the issue of microscopic hematuria multiple times everyday, don't we? How many urine dipsticks have you reviewed in the last 48 hours? How often is there a trace of blood? What does it mean? When should we be concerned? This article is jam-packed with good information to help make decision-making easier, and, more importantly, evidence-based. I'm particularly sensitive to the topic because my 100-year-old mother is a bladder cancer survivor from many years ago.

The authors provide us with a very nice algorithm for microscopic hematuria, factoring the appropriate collection (and recollection if necessary) to ensure that the finding is a real one and not a false positive. Assessment of the upper urinary tract can be done with retrograde pyelogram and fluoroscopy, IVP, or CT scan, each having some advantages over the others, but none proving superior. Upper tract ultrasound is not considered adequate to evaluate the urothelial tract for causes of hematuria, although it is useful to identify renal cysts and calculi.

If you've ever had any of the following questions, then this is the article for you:

* How common is microscopic hematuria and how is it defined?
* What is the prevalence of bladder cancer in women?
* What are bladder cancer risk factors?
* What is the appropriate evaluation in pregnant and nonpregnant women?
* Should there be routine screening for microscopic hematuria?
* When should the gynecologist refer the patient to a urologist?

This article is not only good reading for the gynecologist, but it is even very good reading for non-physician personnel in any office caring for women. The algorithm is simple to understand, the answers to the above questions are evidence-based, and the actions to be taken are clear. A copy of this article should probably be available at every desk in your respective offices for reference at any time.