Ratio between inner cell mass diameter and blastocyst diameter is correlated with successful pregnancy outcomes of single blastocyst transfers

Abstract

Objective: To evaluate the ability to predict pregnancy outcomes of single-blastocyst transfers by measuring the ratio of inner cell mass (ICM) diameter to blastocyst diameter using time-lapse images.

Design: Retrospective cohort study.

Setting: University-affiliated medical center.

Patient(s): One hundred twenty-seven women undergoing a total of 129 blastocyst transfers with intracytoplasmic sperm injection.

Intervention(s): Embryo monitoring by time-lapse microscopy.

Main outcome measure(s): The ratio of ICM diameter to blastocyst diameter in single-blastocyst transfers and clinical pregnancy rates.

Result(s): In phase I of the study, 63 women underwent 65 single blastocyst transfers that resulted in 25 pregnancies (40% of the women). The successfully implanted blastocysts had an average ICM/blastocyst diameter ratio of 0.487 ± 0.086, whereas the average ICM/blastocyst ratio of nonimplanted blastocysts was significantly lower (0.337 ± 0.086). The live-birth rate was 29% (18/63). In phase II, 64 single-blastocyst transfers were performed in 64 women. The ICM/blastocyst diameter ratio was measured, and blastocysts with the highest ratios were chosen for transfer. Forty-three women (67%) with an average ICM/blastocyst diameter ratio of 0.46 achieved pregnancy, and 36 of the 43 pregnancies (84%) resulted in the delivery of a healthy baby. In the 21 women (33%) who failed to achieve pregnancy, the average ICM/blastocyst ratio was 0.45. The resultant positive predictive value was 74%, and the negative predictive value was 70%.

Conclusion(s): The ICM-to-blastocyst diameter ratio is a predictor of implantation and live birth in single-blastocyst transfers, offering a simple, noninterfering method to select blastocysts with high developmental capacity.

Keywords: Blastocyst grading; inner cell mass; pregnancy; time-lapse.