To develop a new tool for gross hematuria, the Hematuria Grading Scale (HGS), and evaluate its consistency in assessing hematuria samples.

The HGS was developed on the basis of an evaluation of sample brightness and saturation using a cyan, magenta, yellow, key (black) color model. Thirty hematuria samples were prepared from human blood by diluting with saline using a standard method. Twenty examiners (5 in each group, including laypeople, nurses, general practitioners, and urologists) participated. Each scored 30 hematuria samples using the HGS under the same conditions without communicating with one another. The intraclass correlation coefficient (ICC) was calculated to assess the reliability of the datasets. Questionnaires for usefulness (Q1) and simplicity (Q2) were obtained from all examiners using a 5-point Likert scale.

The ICC for pooled examiner scores showed a high agreement rate (99.7%, 95% confidence interval [CI] 0.996-0.999). ICC values by group were 99.3% (95% CI 0.989-0.997) for laypeople, 98.8% (95% CI 0.980-0.994) for nurses, 99.1% (95% CI 0.984-0.995) for general practitioners, and 99.2% (95% CI 0.987-0.996) for urologists. Mean Q1 and Q2 scores were 4.70 ± 0.66 and 4.30 ± 1.03, respectively, indicating general satisfaction with the HGS among all examiners.

Evaluations of gross hematuria using the HGS were in high agreement among examiners of all types, and all examiners found the HGS simple and easy to use. The HGS should be a helpful tool for assessment and communication of gross hematuria.