OBJECTIVETo explore the effectiveness of ICSI in overcoming the high incidence of tripronucleates zygotes resulting from insemination in a previous IVF cycle.

METHODSWe retrospectively analyzed the matched-pair cycles in 37 patients with a > 35 % incidence of tripronucleate zygotes in an IVF cycle, with ICSI used in the subsequent cycle, evaluated the incidences of diploid (2PN) and triploid (3PN) zygotesand the number of normal embryos obtained, and compared the rates of clinical pregnancy and embryo implantation between the IVF and ICSI groups.

RESULTSThe mean age of the ICSI group was significantly older than that of the IVF group, while the ampules of gonadotropin and peak E2 showed no remarkable difference between the two. The numbers of follicles at hCG trigger, retrieved oocytes and mature oocytes were markedly lower in the former than in the latter. The percentage of 2PN was significantly higher while that of 3PN significantly lower after ICSI than after IVF (74.24% vs 34.42%; 11.57% vs 51.04%, P < 0.01), and more normal diploid embryos were obtained with ICSI (3.83 +/- 2.08 vs 2.52 +/- 1.71, P < 0.01). Four singletons were achieved in 31 IVF embryo transfer cycles, in comparison with 11 singletons and 3 twins in 36 ICSI embryo transfer cycles. The ICSI group showed significantly higher rates of clinical pregnancy and embryo implantation than the IVF group (38.89% vs 12.90%; 28.33% vs 7.41%, P<0.01).

CONCLUSIONFor women with a high incidence o triploidy in a previous IVF cycle, ICSI can effectively increase the number of normal diploid zygotes.