Guidelines on Hematuria: Best Approach to Microhematuria

The American Urological Association (AUA) published guidelines for asymptomatic microhematuria. The document includes 19 guidelines with recommendation levels ranging from A to C (high to low) and some expert opinion recommendations included. The full guidelines can be accessed at http://www.auanet.org/common/pdf/education/clinical-guidance/Asymptomatic-Microhematuria.pdf.

Q: A 39-year-old woman came to my office for an annual physical, and there was blood in the urine when I sent her urine out for microscopy. She is having abnormal menses, so she could not be sure this was not contamination (and neither could I). I repeated the urine and it was positive for blood on micro. What do I do now? Where do I refer her?

There are numerous causes of microhematuria, and the answer can often be found by considering the possible differential diagnoses. The causes of hematuria include urinary tract infection (UTI), bladder or kidney stones, kidney disease, use of certain medications, strenuous exercise, and trauma. ² Health care professionals should follow a process to make logical assessments and decisions in the care of this 39-year-old woman with microhematuria.

What to do first? The first step is to obtain a complete history, including any associated symptoms, medication history, last menstrual period, family history, previous medical history, recent trauma, strenuous exercise, and easy bruising or bleeding. In this case, since the urinalysis was repeated and remained positive for hematuria, the next step is to consider a renal function panel and complete blood count (CBC).

A renal function panel (sodium, potassium, chloride, carbon dioxide, anion gap, glucose, urea reduction ratio, creatinine, albumin, calcium, and phosphorous) will help to rule out existing renal function dysfunction.

The CBC will help to rule out any blood loss or presence of systemic involvement. Also, look at other results noted on the urinalysis, such as protein, nitrates, and leukocytes. Looking for protein will help the clinician determine whether fever, diabetes, chronic kidney disease, or hypertension may be the cause. Nitrates will appear as a result of UTI, and leukocytes may suggest a UTI or possible contamination. Dysmorphic red blood cells (RBCs with irregular shapes) found on the microscopic exam of the urine indicate a glomerular etiology, in which case the patient should be referred to nephrology for possible renal biopsy. If the red blood cells are nonglomerular (ie, the glomerulus is not the source of the bleeding) and there is no other obvious cause, then the patient should be referred to urology.

When is it time to refer? If microhematuria is persistent, the patient will need to be referred to a urologist for further evaluation. According to AUA guidelines 7, 8, and 16 through 19, ¹ cystoscopy should be considered for patients 35 or older with asymptomatic hematuria. For younger patients, a cystoscopy may be considered at the discretion of the provider. Although blue light cystoscopy has FDA approval, in the opinion of the AUA, the risks of the technique outweigh its benefits. Blue light cystoscopy is reported to improve identification of bladder tumors. ³

For patients with a history of persistent asymptomatic hematuria, no further urinalyses are needed after two consecutive yearly tests with negative results. Those with a negative urologic workup should have urinalyses performed annually. If a patient has persistent or recurrent asymptomatic microhematuria with an initially negative urologic workup, then patients should be considered for reevaluation by urology every 3 to 5 years. ¹