Cytological and Histological Diagnosis
The sections examined and reviewed by two pathologists had no disagreement finally. In histological diagnosis, there were 60 positive cases containing 4 atypical hyperplasia and 56 endometrial cancers. The negative cases contained proliferative endometrium (1 case), secretory endometria (10 cases), atrophic endometria (7 cases), mixed endometria (26 cases), simple hyperplasia (69 cases), complex hyperplasia (5 cases), and endometrial polyps (2 cases).
The cytological diagnosis included proliferative endometrial cells (49 cases by H-E stain, 57 cases by Papanicolaou stain), secretory endometrial cells (17 cases by H-E stain, 9 cases by Papanicolaou stain), atrophic endometrial cells (3 cases by H-E stain, 4 cases by Papanicolaou stain), simple hyperplasia endometrial cells (41 cases by H-E stain, 44 cases by Papanicolaou stain), complex hyperplasia endometrial cells (2 cases by H-E stain, 2 cases by Papanicolaou stain), atypical hyperplasia endometrial cells (30 cases by H-E stain, 23 cases by Papanicolaou stain), endometrial cancer endometrial cells (28 cases by H-E stain, 30 cases by Papanicolaou stain), and no endometrial cells (10cases by H-E stain, 11 cases by Papanicolaou stain). Endometrial atypical hyperplasia and carcinoma were considered as positive results. The positive results of H-E stain were 58, and those of Papanicolaou stain were 53.
The characteristics of the endometrial cytological diagnosis by H-E and Papanicolaou stain were showed in Table S2 . There were 135 cases with completely consistent results (distinguished by benign and malignant endometrial lesions). The simple hyperplasia diagnosed by both methods were in the majority (33 cases), followed by proliferative endometria (32 cases). Total 7.32% (12/164) of the samples were positive in H-E stain and negative in Papanicolaou stain. And 4.27% (7/164) of them were positive in Papanicolaou stain and negative in H-E stain.
All participants were stratified based on histological and cytological results by H-E and Papanicolaou stain (Figure 1 ). Taking the histological results as gold standard, we compared the cytological diagnoses of H-E and Papanicolaou stain respectively (Table S3 ). The Cohen’s kappa value was 0.78, which indicated a high consistency between them.
The Se, LR+, r, PPV and NPV of H-E stain were higher than those of Papanicolaou stain, while the FNR, LR- of H-E stain were lower than those of Papanicolaou stain. The Sp and FPR of them were same (Table 2 ). The difference of Se between them was statistically significant(χ2 = 9.068, P = 0.003). Therefore, H-E stain is considered more accurately than Papanicolaou stain.