New Recommendations for Evaluating Microscopic Hematuria
Patients are sent to me three or four times per week for microscopic hematuria. That means that they have red blood cells (RBCs) found on urinalysis but not seen with the naked eye.
In the past, we have launched a full-on evaluation of microscopic hematuria if we find 3 or greater RBCs seen in a “high power field” (HPF). That means that when the lab technician looks at someone’s urine sample under a powerful microscope, they see three or more RBCs staring back at them.
The “full-on” evaluation includes vitals signs, blood work to check kidney function, a “urine cytology” to look for abnormal cells, a cystoscopy (looking inside the bladder with a camera) and a CT scan of the abdomen and pelvis. The CT scan looks for kidney stones or anything else along the entire urinary tract from the kidneys to the bladder that could be causing the RBCs to appear on the urinalysis. The majority of the time, we never find a reason for the RBCs, and we chalk it up to “familial microscopic hematuria.” That simply means it might just be genetic.
Recommendations hot off the press may change our criteria. The American College of Obstetricians and Gynecologists (the College) and the American Urogynecologic Society (AUGS) state:
• Urinalysis is a commonly performed test, and microscopic hematuria is a common finding.
• Renal cancer and bladder cancer are more common in men than women.
• 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%.
• The College and AUGS 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.
• The College and AUGS 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.
These new recommendations could prevent many women from undergoing unnecessary tests and anxiety.
Committee on Gynecologic Practice, A.U.S., Committee Opinion No.703: Asymptomatic Microscopic Hematuria in Women. Obstet Gynecol, 2017. 129(6): p. e168-e172.