Table 17-2. Classification systems for Papanicolaou smears

Numerical	Dysplasia	CIN	Bethesda System
1	Benign	Benign	Normal
2	Benign with inflammation	Benign with inflammation	Normal, ASC-US
3	Mild dysplasia	CIN I	Low-grade SIL
3	Moderate dysplasia	CIN II	High-grade SIL
3	Severe dysplasia	CIN III
4	Carcinoma in situ
5	Invasive cancer	Invasive cancer	Invasive cancer

Key:
CIN = cervical intraepithelial neoplasia;
ASC-US = atypical squamous cells of undetermined significance;
SIL = squamous intraepithelial lesion.