Use of the Endometriosis Fertility Index to Predict Natural Pregnancy after Endometriosis Surgery: A Single-Center Study

Aims: Our objective was to predict natural pregnancy after endometriosis surgery using the endometriosis fertility index (EFI). Methods: A retrospective medical records review was conducted, examining patients surgically treated for endometriosis at a single center in Korea between January 2009 and February 2015. In total, 68 women attempting natural conception were analyzed by assessing age, preoperative serum CA-125, body mass index, revised American Fertility Society (rAFS) stage, EFI, and pregnancy outcome. Kaplan-Meier estimates and log-rank tests were used to generate cumulative natural pregnancy rate curves based on an EFI cut-point. A receiver-operating characteristic (ROC) curve was plotted for EFI. Results: Seventy-seven patients attempted conceptions, resulting in 33 natural and 9 assisted conceptions. Excluding assisted conceptions, the mean EFI scores of 68 women who were not pregnant and pregnant were 5.43 +/- 0.36 and 6.88 +/- 0.28 respectively. The relation between EFI and natural pregnancy was significant (cumulative overall pregnancy rate, p = 0.006), whereas rAFS stage was not (univariate logistics, p = 0.853). The cut-point for maximum natural pregnancy outcomes was 6 (area under ROC curve = 0.710, 95% CI 0.586-0.835). Conclusion: The EFI is a reliable staging system for predicting natural pregnancy after endometriosis surgery. EFI scores can be used to guide postoperative treatment of women with endometriosis.