P-563 The effect of embryo culture time on concordance rates between invasive and non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) in spent culture media (SCM) analysis

Study question

To evaluate different embryo culture times (day5 versus day6) to understand the ideal time-frame for the performance of concordance analysis between invasive and non-invasive PGT-A(niPGT-A)

Summary answer

Different levels of ploidy concordance rates were observed between day5 and day6 groups: 72,6% versus 84,8%, respectively

What is known already

The recent data supports that a non-invasive approach for evaluating embryo ploidy status may be an alternative to standard invasive methods. Embryo cell-free DNA(cfDNA) released into culture media during in-vitro embryo development represents the potential source for this analysis. The release of cfDNA from embryos is expected to be directly proportional to embryo culture time and late-stage released cfDNA may be more representative of the embryo. Therefore, it is important to estimate the most effective time frame of the culture that will provide the most conclusive data from spent-culture-media(SCM) without adversely affecting the development of the embryo

Study design, size, duration

A total of 334 SCM from blastocyst stage embryos have been included in this study. The SCM samples were divided in 2 subgroups according to the embryo culture time as day5 (n = 154) and day6 (n = 180). The cfDNA of SCM samples were amplified by whole genome amplification(WGA) and analyzed by next generation sequencing(NGS) in parallel to day5 or day6 trophectodermal(TE) biopsied samples of their corresponding embryos. Ploidy status and concordance were compared between two groups

Participants/materials, setting, methods

Day3 embryos were washed and transferred in 20µl fresh culture media until the biopsy. SCM samples were collected in PCR tubes and stored at -20 °C while embryos were biopsied for standard PGT-A analysis. Both SCM and corresponding TE biopsy samples were amplified by Sureplex(Vitrolife). Then TE and SCM samples were analyzed by next-generation sequencing(NGS) using MiSeq® System (Illumina). Data analysis has been done by Bluefuse Multi Software 4.5(Illumina) for all SCM and TE samples

Main results and the role of chance

A successful DNA amplification rate (>30ng/µl) was obtained in both day5 and day6 groups with 95,5% (147/154) and 99,4% (179/180) respectively. The DNA concentration after WGA was ranging between 30.1-122.5ng/µl and 38.5-123.2ng/µl in day5 and day6 groups respectively. Not conclusive (NC) results including a noisy NGS profile and chaotic chromosome aneuploidies (>5 chromosomes) were excluded in both groups. Therefore, 64,6% (95/147) of SCM samples in day5 group and 81,0% (145/179) of SCM samples in day6 group were conclusive for NGS analysis. The ploidy concordance rate between SCM and TE samples (euploid vs euploid, aneuploid vs aneuploid) was 72,6% (69/95) in day5 and 84,8% (123/145) in day6 group. In day5 group, the false-negative rate was 10.5% (10/95), and false-positive rate was 16.8% (16/95) while in day6 group the false-negative rate was 6,8% (10/145), and false-positive rate was 8,2% (12/145). Sensitivity and specificity were calculated as 83,6% and 52,9% in day5 group, and 90,9% and 65,7 in day6 group respectively

Limitations, reasons for caution

We have high number of samples in our study, but larger prospective studies may change the significance of ploidy concordance. One of the important issues in SCM analysis is the maternal DNA contamination risk which cannot be revealed always. Therefore the use of molecular markers would increase the reliability

Wider implications of the findings

A non-invasive approach for aneuploidy screening may be an alternative to standard PGT-A procedure with invasive embryo biopsy but the evaluation of ideal culture time is crucial for the performance of niPGT-A method. Our study demonstrates that the late collection time of SCM provides significantly better ploidy concordance rates

Trial registration number

Not applicable

P–582 High level of concordance between invasive and non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) at day5 and day6–7

Study question

To explore ploidy concordance between invasive and non-invasive PGTA (niPGT-A) at different embryo culture time.

Summary answer

High level (>84%) of concordance rate for ploidy and sex, sensitivity (>88%), and specificity (76%) were obtained for both day6/7 samples and day5 samples.

What is known already

The analysis of embryo cell free DNA (cfDNA) that are released into culture media during in vitro embryo development has the potential to evaluate embryo ploidy status. However, obtaining sufficient quality and quantity of cfDNA is essential to achieve interpretable results for niPGT-A. More culture time is expected to be directly proportional to the release of more cfDNA. But embryo culture time is limited due to in-vitro embryo survival potential. Therefore, it is important to estimate the duration of the culture that will provide the maximum cfDNA that can be obtained without adversely affecting the development of the embryo.

Study design, size, duration

A total of 105 spent culture media (SCM) from day5-day7 blastocyst stage embryos have been included in this cohort study. The cfDNA of SCM samples were amplified and analyzed for niPGT-A by NGS analysis. The SCM samples were divided into 2 subgroups according the embryo culture hours (Day5 and Day6/7 group). The DNA concentration, informativity and euploidy results have then been compared with their corresponding embryos after trophectoderm biopsy (TE) and PGT-A analysis by NGS

Participants/materials, setting, methods

Embryos cultured until Day3 washed and cultured again in 20µl fresh culture media until embryo biopsy on Day5, 6, or 7. After biopsy SCM samples were immediately collected in PCR tubes and conserved at –20 °C until whole genome amplification by MALBAC® (Yicon Genomics). The TE and SCM samples were analyzed by next-generation sequencing (NGS) using Illumina MiSeq® System. NGS data analysis has been done by Bluefuse Multi Software 4.5 (Illumina) for SCM and TE samples

Main results and the role of chance

Only the SCM samples which have an embryo with a conclusive result were included in this cohort (n = 105). Overall 97.1% (102/105) of SCM samples gave a successful DNA amplification with a concentration ranging 32.4–128.5ng/µl. Non-informative (NI) results including a chaotic profile (>5 chromosome aneuploidies) were observed in 17 samples, so 83.3%(85/102) of SCM samples were informative for NGS data analysis. Ploidy concordance rate with the corresponding TE biopsies (euploid vs euploid, aneuploid vs aneuploid) was 84.7% (72/85). Sensitivity and specificity were 92,8% and 76,7%, respectively with no significant difference for all parameters for day 6/7 samples compared with day 5 samples. The false-negative rate was 3.5% (3/85), and false-positive rate was 11.7% (10/85).

Limitations, reasons for caution

The sample size is relatively small. Larger prospective studies are needed. As this is a single-center study, the impact of the variations in embryo culture conditions can be underestimated. Maternal DNA contamination risk cannot be revealed in SCM, therefore the use of molecular markers would increase the reliability.

Wider implications of the findings: Non-invasive analysis of embryo cfDNA analyzed in spent culture media demonstrates high concordance with TE biopsy results in both early and late culture time. A non-invasive approach for aneuploidy screening offers important advantages such as avoiding invasive embryo biopsy and decreased cost, potentially increasing accessibility for a wider patient population.

Trial registration number

Not applicable