Comparison of the validity of preimplantation genetic diagnosis for embryo chromosomal anomalies by fluorescence in situ hybridization on one or two blastomeres.

Is it necessary to analyze two blastomeres in preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridization (FISH) or is one blastomere enough, as suggested by some teams? We analyzed the sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), false positives (FP), false negatives (FN), and the efficiency (Eff) of FISH performed on one (Group I) or two (Group II) blastomeres. Ninety embryos were analyzed (day 3), 19 blastocysts were replaced (day 5), 64 embryos were reanalyzed (day 5), (Group I = 23; Group II = 41). No differences were observed between the two groups for all of the parameters considered, but one false negative was observed in Group I. Furthermore, two embryos from Group II, which had a discordant diagnosis at PGD (one blastomere being normal and one abnormal), were read as abnormal after reanalysis. The accidental biopsy of the normal blastomere could have lead to the selection of these 2 embryos for transfer, causing a misdiag...