Laboratory Reporting Parameters of Microhematuria within Academic Medical Centers and Commercial Laboratories: Implications for Interpreting the 2020 AUA Guidelin
Mohannad Awad, MD1, Mackenzie Goldsmith, MD2, Luke Hallgarth, MD1, Jay Raman, MD2, Kevan Sternberg, MD1.
1University of Vermont Medical Center, BURLINGTON, VT, USA, 2Penn State Health Milton S. Hershey Medical Center, Hershey, PA, USA.
BACKGROUND: To explore how laboratories in the United States report red blood cell per high powered field (RBC/HPF) counts on urinalysis and to evaluate whether their methods can effectively risk stratify patients in accordance with the 2020 American Urological Association/Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (AUA/SUFU) microhematuria (MH) guidelines.
METHODS: Reporting methods for RBC/HPF counts (ranges or actual counts) were collected by querying urologists in United States academic medical institutions or contacting labs directly. Study outcomes were (1) to explore whether the reporting schemes were concordant with the risk stratification groups in the new MH guideline (3-10 [low risk], 11-25 [intermediate risk], and more than 25 [high risk]) and (2) to evaluate the potential for misclassification of these risk groups based on reporting methodology.
RESULTS: Methods of reporting RBC/HPF count were collected from 141 laboratories. Seventy-two (51%) use ranges, while the remainder use actual counts or actual counts to a certain threshold number. Sixty (43%) report ranges that do not include cutoffs concordant with the MH guidelines risk stratification groups. Fifty-six (40%) do not include the cutoff of 25 RBC/HPF which impacts segregation of intermediate and high risk groups. Sixteen (11%) do not include the cut-off of 3 RBC/HPF that defines the presence of MH. Of labs that report ranges, only 12/72 (17%) include all the same cutoffs of the MH guidelines risk stratification groups. Figure 1 illustrates the distribution of labs reporting RBC/HPF counts that are concordant with MH risk stratification cutoffs vs those that are not and the breakdown of possible misclassifications that could arise from not including these cutoffs in the reported ranges.
CONCLUSIONS: Asignificant number of laboratories report RBC/HPF counts in ranges that differ from thresholds in the 2020 AUA/SUFU guideline. The implication is potential misclassification of microhematuria both at minimum threshold diagnosis (3 RBC/HPF), but additionally between intermediate and high risk groups. Standardization of reporting schemes to actual RBC/HPF counts may allow improved adherence to guidelines while providing data for future guideline development. 
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