Number of biopsied trophectoderm cells is likely to affect the implantation potential of blastocysts with poor trophectoderm quality.

OBJECTIVE: To evaluate whether the developmental potential of the blastocyst is affected by the number of trophectoderm (TE) cells biopsied in preimplantation genetic diagnosis (PGD) cycles.
DESIGN: Retrospective study.
SETTING: University-affiliated center. PATIENT(S): Women underwent PGD cycles of blastocyst biopsy and fluorescence in situ hybridization analysis. INTERVENTION(S): Not applicable. MAIN OUTCOME MEASURE(S): Biopsied TE cell number of blastocysts, survival, and implantation rates. RESULT(S): The biopsied TE cell number was affected by the TE quality and experience of different embryologists. The diagnostic efficiency increased when from one to five cells were biopsied (86.7%, 91.7%%, 96.0%, 96.8%, to 98.7%) and was maximized when more than six cells were biopsied. To compare the clinical efficiencies, blastocysts were divided into four groups according to biopsied TE cell number: 1-5, 6-10, 11-15, and 16-41. For the blastocysts with grade A TE score, no significant difference was observed in the survival and implantation rates among the four groups. For the blastocysts with grades B and C TE scores, the survival rates showed no significant differences among the four groups, but a significant decreasing trend in implantation rates was observed with increasing biopsied TE cell number. CONCLUSION(S): The implantation potential is negatively affected by the biopsied TE cell number in blastocysts with poor TE morphological score.