Estradiol to Mature Oocyte Ratio can Predict Morphokinetics of Embryos and Cycle Outcome

Introduction: Several studies in the past reported the ideal ratio of peak estradiol level and collected oocytes in agonist down regulation protocols versus antagonist cycles. They all agreed that the E2/oocyte ratio is an important predicting parameter for IVF success rate

Aim: To find the cutoff ratio of E2/M2 and to evaluate the correlation with embryos morphokinetics using EmbryoScope™ with regard to treatment protocol IVF cycle outcome.

Material and Methods: A retrospective cohort study. Records of all fresh cycles that their embryos were cultured in a time-laps incubator were evaluated. Embryos were scored by EmbryoScope™ and correlated with E2/M2 ratio and clinical pregnancy rates.

Results: Two thousand five hundred thirty two oocytes were collected from 179 patients undergoing OPU procedures. The ratio of E2 levels on day of HCG to the number of M2 oocytes (E2/M2) was calculated and correlated to embryo morphokinetic quality and cycles outcomes. A ROC analysis demonstrated a correlation between E2/M2 ratio cut-off of 204.2 and pregnancy rate. E2/M2 below 204.2 can predict clinical pregnancy with a sensitivity of 69.5% while E2/M2 ratio of higher than 204.2 predicts cycles failure with a specificity 62.1% (P<0.001). We used this cut-off to evaluate cycle outcome. We found that E2/M2 ratio < 204.2 was correlated with higher fertilization , higher rate of top quality embryo (KID score 4-5 29% Vs 20%, ESHRE 2-3 28% Vs 17.5%, P < 0.0001).

Conclusions: E2/M2 ratio correlated with embryo morphokinetics and can be used to predict cycles outcomes.