Cervical erosion is generally divided into three grades: Grade 1 cervical erosion refers to erosion covering less than one-third of the total cervical area, which is also called mild erosion. Grade 2 erosion, also known as moderate-to-severe erosion, refers to the erosion covering about two-thirds of the total area, which is considered moderate, being the middle grade of erosion. Grade 3 cervical erosion is the last and most severe grade, also known as severe erosion. In this case, the erosive area exceeds two-thirds of the entire cervical area, and may even involve the entire cervix. This condition is generally more serious and typically requires examination including a TCT (ThinPrep Cytologic Test) and HPV (Human Papillomavirus) co-screening to investigate the possibility of cervical lesions. Further assessments might include a colposcopy or localized treatment, as severe erosion could lead to symptoms like contact bleeding and increased discharge that need to be addressed.