| Pathological grading | Description of pathological changes |
| - | HK-2 cells were uniform in shape and size, and no obvious pathological change was found. |
| + | Individual cell degeneration, karyopyknosis and hyperchromatic were observed, the proportion of cytoplasm and nucleus was abnormal. |
| ++ | Focal or small flakes cell degeneration, karyopyknosis and hyperchromatic were observed, the proportion of cytoplasm and nucleus was abnormal. |
| +++ | Large area diffuse cell degeneration, karyopyknosis and hyperchromatic were observed, the proportion of cytoplasm and nucleus was abnormal, loose arrangement between cells was found. |