Re-denudation of residual cumulus cells on day 3 increases the accuracy of cell-free DNA detection in spent embryo culture medium

Abstract

Purpose: To evaluate the effect of two-step denudation on maternal contamination, ploidy concordance between spent embryo culture medium (SCM) and trophectoderm, blastocyst formation, and clinical outcome.

Methods: Sibling embryos of the same couple were re-denuded (treatment) and not re-denuded (control) on day 3, and trophectoderm biopsy and SCM collection were performed on day 5/6. Sex chromosomes of 20 pairs of SCM and biopsy samples were analyzed to determine the reduction in maternal contamination. Blastocyst formation, implantation, and ongoing pregnancy rates were analyzed by recruiting 565 cleavage embryos on day 3. A total of 113 SCM samples and their corresponding trophectoderm results were collected for ploidy concordance analysis.

Results: The detection rate of XX between the treatment and control groups was significant (12/20 (60.0%) versus 19/20 (95.0%), p = 0.02). Concordance of sex chromosomes between the two groups was significant (17/20 (85.0%) versus 8/19 (42.1%), p = 0.003). There were no significant differences in blastocyst formation rate, implantation rate, and ongoing pregnancy rate between the two groups. Among the 113 pairs of SCM and its corresponding trophectoderm, 37 cases (33.33%) were completely concordant, 39 cases (35.14%) were partially concordant, and 35 cases (31.53%) were discordant.

Conclusion: Our results suggest that re-denudation on day 3 reduces the influence of maternal contamination and improves the accuracy of cfDNA detection. Moreover, the procedure had no significant effect on blastocyst formation, implantation, and ongoing pregnancy rates. In addition, the ploidy concordance approached 70% compared with biopsy, which is acceptable but still not ideal.

Keywords: Cell-free DNA; Cumulus cells; Denudation; Preimplantation genetic testing; Spent embryo culture medium.