[Effects of cleavage-stage biopsy on in vitro development of human embryos]

To evaluate the effects of biopsy methods, biopsy timing and the number of cell removed on in vitro development of embryos.

One hundred and fifty four embryos of good morphology from in vitro fertilization patients were studied. Sixty-six embryos were allocated to the following three groups: chemical drilling biopsy group (26), mechanical drilling biopsy group (26) and control group (20). One cell was removed from the embryos of the two biopsy groups. The remaining 88 embryos were allocated to two groups: biopsy group (44) and control group (44). Two cells were removed from biopsy group by chemical drilling method. The stage of the embryo before biopsy, biopsy time, lysed blastomere, growth potential and hatching capacity of the biopsied embryos, total cell number at the blastocyst stage were recorded and evaluated.

The mean time of biopsy in the chemical drilling group (231 +/- 20) seconds was significantly shorter than that in the mechanical drilling group (262 +/- 23) seconds (P < 0.01). The proportion of embryo developing to blastocyst stage was higher in chemical drilling group as compared with the mechanical group (65% versus 35%, P < 0.05). The total cell number at the blastocyst stage was fewer than those in the 7 to 8-cell embryo and >/= 9-cell embryo groups in the 6-cell embryo group (44 +/- 4 versus 49 +/- 5, 50 +/- 6; P < 0.05). At 9- to 10-cell stage, the proportion developing to the blastocyst stage was reduced in compacted embryos (20%) compared with control group (67%, P < 0.05) also more lysed blastomeres after biopsy were found in compacted embryos (50%) compared with uncompacted embryos (17%). The growth capacity to the blastocyst stage and the total cell number of the blastocyst were not different between one cell removal group and two cells removal group (P > 0.05). However, the proportion developing to the blastocyst stage was reduced after the removal of two cells from the 6-cell stage in comparison to the control (1/8 versus 5/8, P < 0.05).

Compared with mechanical drilling biopsy, chemical drilling technique takes shorter timer and is safer. The suitable biopsy timing was >/= 7-cell stage before embryo compacting. The removal of two cells from >/= 7-cell would not impair in vitro development of embryos.