Preimplantation genetic testing: polar bodies, blastomeres, trophectoderm cells, or blastocoelic fluid?

OBJECTIVE: To investigate the blastocoelic fluid (BF) for the presence of DNA that could be amplified and analyzed; the extent to which its chromosomal status corresponds to that found in trophectoderm (TE) cells, polar bodies (PBs), or blastomeres; and the identification of segmental abnormalities. DESIGN: Longitudinal cohort study. SETTING: In vitro fertilization unit. PATIENT(S): Fifty-one couples undergoing preimplantation genetic screening or preimplantation genetic diagnosis for translocations by array-comparative genomic hybridization on PBs (n = 21) or blastomeres (n = 30). INTERVENTION(S): BFs and TE cells were retrieved from 116 blastocysts, whose chromosome status had already been established by PB or blastomere assessment. Separate chromosome analysis was performed in 70 BFs. MAIN OUTCOME MEASURE(S): Presence of DNA in BFs, evaluation of the chromosome condition, and comparison with the diagnosis made in TE cells and at earlier stage biopsies. RESULT(S): DNA detection was 82%, with a net improvement after refinement of the procedure. In 97.1% of BFs, the ploidy condition corresponded to that found in TE cells, with one false positive and one false negative. The rate of concordance per single chromosome was 98.4%. Ploidy and chromosome concordance with PBs were 94% and 97.9%, respectively; with blastomeres, the concordances were 95% and 97.7%, respectively. Segmental abnormalities, which were detected in PBs or blastomeres of 16 blastocysts, were also identified in the corresponding BFs. CONCLUSION(S): BF represents to a good extent the blastocyst ploidy condition and chromosome status when compared with TE cells. If the proportion of clinically useful BFs is improved, blastocentesis could become the preferred source of DNA for chromosomal testing.

Blastocentesis: a source of DNA for preimplantation genetic testing. Results from a pilot study.

OBJECTIVE: To investigate the presence of DNA in blastocyst fluids (BFs) and to estimate whether the chromosomal status predicted by its analysis corresponds with the ploidy condition in trophectoderm (TE) cells, the whole embryo, and that predicted by polar bodies (PBs) or blastomeres. DESIGN: Prospective study. SETTING: In vitro fertilization unit. PATIENT(S): Seventeen couples undergoing preimplantation genetic screening with the use of array comparative genomic hybridization on PBs (n = 12) or blastomeres (n = 5). INTERVENTION(S): BFs and TE cells were retrieved from 51 blastocysts for separate chromosomal analysis. MAIN OUTCOME MEASURE(S): Presence of DNA in BFs and assessment of the corresponding chromosome condition; correlation with the results in TE cells and those predicted by the analysis done at earlier stages. RESULT(S): DNA was detected in 39 BFs (76.5%). In 38 of 39 cases (97.4%) the ploidy condition of BFs was confirmed in TE cells, and the rate of concordance per single chromosome was 96.6% (904/936). In relation to the whole embryo, the ploidy condition corresponded in all cases with a per-chromosome concordance of 98.1%. The testing of PBs and blastomeres had 93.3% and 100% prediction of BF ploidy condition with a concordance per chromosome of 93.5% and 94%, respectively. CONCLUSION(S): Blastocentesis could represent an alternative source of material for chromosomal testing, because the BF is highly predictive of the embryo ploidy condition and chromosome content. Our data confirm the relevance of the oocyte and of the early-cleavage embryo in determining the ploidy condition of the resulting blastocyst.