An embryo cleavage pattern based on the relative blastomere size as a function of cell number for predicting...

To analyze whether the cleavage pattern redefined for all cleavage stages according to the relative blastomere size as a function of cell number has an additive value in predicting implantation potential of day-2 and day-3 embryos.

Retrospective analysis of standard embryo morphologic parameters (cleavage rate and degree of fragmentation) supplemented by cleavage pattern findings of 347 implanted embryos compared with those of a matched control group of 307 embryos that failed to implant.

University-based tertiary medical center.

Two hundred and nine women with successful implantation and 181 controls matched for age and demographic parameters with failed implantation.

In vitro fertilization (IVF), embryo assessment, and embryo transfer.

Determination of cleavage patterns in synchronized and unsynchronized cleaving embryos and correlations with implantation outcomes.

Statistically significantly more embryos of the implanted group had good cleavage patterns compared with the failed implantation group (88% vs. 70%). A good cleavage pattern predicted implantation outcome even for nonsynchronized cleaving blastomeres at three, five, six, and seven cells (79% vs. 59%). Regression analysis demonstrated that adding cleavage pattern to the scoring system increased our ability to predict implantation in the training set; the area under the curve was the highest (0.707) as was the proportion of correct classification (>70%) when the cleavage pattern was assessed on both days 2 and 3.

When combined with measurements of the cleavage rate and degree of fragmentation, the cleavage pattern refines our ability to predict the likelihood of implantation, representing a definitive tool in the selection of top-quality embryos.