P-553 Develop an Algorithm to Assess Maternal Contamination in the Embryo Spent Culture Medium

Abstract Study question Can algorithms be developed and validated to assess maternal contamination in embryo spent culture medium (SCM) and correct copy number variations (CNVs)? Summary answer An algorithm that leverages the ratio of X and Y chromosomes, coupled with the quantitative parental contamination test, was developed to accurately determine maternal contamination. What is known already Maternal contamination is a frequent challenge in non-invasive Preimplantation Genetic Testing (niPGT) using SCM, potentially affecting the accuracy of genetic analysis. Study design, size, duration We developed two algorithms to confirm the proportion of maternal contamination based on the mosaic ratios of X and Y chromosomes and quantitative parental contamination test. Following the initial assessment, we applied the CNV correction algorithm to correct CNVs in embryos that were found to have maternal contamination. The performance of the algorithms was comprehensively evaluated using 317 SCM samples, ensuring their reliability and accuracy. Participants/materials, setting, methods 317 culture medium samples were analyzed in the study. Maternal contamination was determined using X and Y chromosome mosaic ratios and quantitative parental contamination test. CNV correction algorithms were applied to adjust the ploidy status of embryos that were identified as having maternal contamination in the culture medium. Main results and the role of chance Out of 317 analyzed embryo culture medium samples, maternal contamination was detected in 88 embryos, accounting for 27.8%. Of the 88 embryos, 19 were euploid, 36 were mosaic and 33 were aneuploidy. Subsequent re-evaluation with the CNVs correction algorithm led to the reclassification of the initial ploidy status: 2 out of 19 euploid embryos were redefined as mosaic, and 5 as aneuploidy; 23 out of 36 mosaic embryos were redefined as aneuploid, and 3 as euploid. The aneuploid status of the initial 33 embryos remained unchanged after re-assessment. Limitations, reasons for caution The current sample size of embryos included in the analysis is small, and more samples are still needed to verify the accuracy of the algorithms. Wider implications of the findings The algorithms improve the accuracy of embryo genetic testing by addressing maternal contamination, offering a robust method for refining niPGT assessments. Trial registration number No