Abstract: Objective：To assess the value of endometriosis fertility index（EFI） in predicting the none-ART pregnancy outcome after conservative surgery for stage Ⅲ-Ⅳ endometriosis（EMs）-associated infertility. Methods：Medical documents of 48 infertile patients who were confirmed of stage Ⅲ-Ⅳ EMs by laparoscopy were retrospectively studied from January 2011 to December 2012 in Peking University of Shenzhen Hospital, The EFI score was calculated on history and detailed surgical findings. All patients were followed up to assess fertility outcome. Results：The overall postoperative none-ART pregnancy rate within 24 months was 52.1%. The postoperative none-ART pregnancy rate was 41.7%，8.3% and 2.1% in the first six month, the 7 to 12 months and the 13 to 24 months, there were statistically difference at the diffierent periods of follow-up （χ2=30.301，P=0.000）. The postoperative none-ART pregnancy rate was correlated with EFI scoring and ovarian simulation （P＜0.05）. However, the postoperative pregnancy rate had no correlation with r-AFS staging（P＞0.05）. ROC curve analysis of EFI showed that the area under curve was 0.681（95% CI：0. 527-0. 834，P=0.033）. The critical value of pregnancy predicted by EFI within two years after the operation was 5.5, with sensitivity of 85.2% and specificity of 42.9%. Conclusions：EFI scores could well predict none-ART pregnancy rate in patients with stage Ⅲ- Ⅳ EMs -associated infertility. EFI scores may be used to guide postoperative treatment.

Key words: Endometriosis, Fertility index, Pregnancy rate, Infertility, female, Laparoscopes