Embryo Quality and Grading
The majority of embryos produced in our laboratory are cultured for 5 days after egg harvest. As embryos develop, they are closely watched by our embryologists and each is assigned a grade. We use the Gardner system to grade 5-day old blastocysts which uses the ranking AA-quality (considered the best and rarely seen in the laboratory) to DD-quality (those felt unsuitable for transfer). Day-3 embryos are ranked by the number of cells that are present along with a score from 1 to 4 (1-best, 4-worst). When you arrive for your embryo transfer, our physician will go over the number of embryos you have, the grade of each and make a recommendation, based on input from our embryologists, as to which embryos should be transferred and how many. We try to adhere strictly to the American Society of Reproductive Medicine's guidelines regarding the number of embryos transferred.
Please note that there is no standard classification system used by all fertility centers. Although most centers use the Gardner grading system for blastocysts, each center created their own system for grading day-2 and 3 embryos as the technology developed and, at this point, it would be too difficult for all centers to try and use a standard grading method.
Fragmentation
During cell division, little pieces may break off and result in a fragmented embryo. A small amount of fragmentation is normal, but as the degree of fragmentation increases the odds of successful implantation are diminished. In fact, significant fragmentation has been associated with chromosomally abnormal embryos. All embryos evaluated in our lab are assigned a fragmentation score by estimating the percentage of the embryo volume that is replaced by fragments. Up to 10% fragmentation is considered good quality, 10-20% is okay and embryos with more than 20% fragmentation are considered suboptimal. While a successful pregnancy can be achieved with a fragmented embryo, the odds decrease as fragmentation increases.
