To compare the 2012 American Urological Association (AUA) and 2020 AUA/Society of Urodynamics, Female Pelvic Medicine & Urogenital Reconstruction (SUFU) microscopic hematuria (MH) guidelines as applied in 1,018 patients with MH, to confirm of risk groups and to investigate the natural history of patients with MH.

Patients who had undergone a complete urological evaluation for MH according to the 2012 AUA MH guidelines were identified retrospectively. All the patients were then classified into low-, intermediate-, or high-risk for urinary tract malignancy according to the updated 2020 AUA/SUFU MH guidelines, for a second evaluation. The results of the first and second evaluations using the previous 2012 AUA and updated 2020 AUA/SUFU MH guidelines, respectively, were then compared.

A total of 1018 patients with MH were identified. The urinary tract malignancy rate was 3.3% (34 of the 1,018 patients). According to the 2020 AUA/SUFU MH guidelines, there were 218 patients (21.4%) in the low-risk group, 447 patients (43.9%) in the intermediate-risk group, and 353 patients (34.6%) in the high-risk group. All the 34 patients with malignancy were from the intermediate- or high-risk group who require further urological evaluation. There was no patient with newly developed urinary tract malignancy at the median follow-up time of 28 months (12-58).

The use of the updated 2020 AUA/SUFU MH guidelines may reduce the number of diagnostic procedures without compromising the diagnosis of life-threatening malignant lesions.