Three-dimensional partial zona dissection for preimplantation genetic diagnosis and assisted hatching

Objective: To develop a new approach to partial zona dissection of oocytes and embryos for facilitating preimplantation genetic sampling and assisted hatching. Design: Controlled clinical study. Setting: Preimplantation genetic diagnosis and IVF program, Reproductive Ge netics Institute/IVF Illinois, Chicago, Illinois. Patient(s): Three hundred forty patients undergoing IVF in whom preimplanta tion genetic diagnosis or assisted hatching was required. Intervention(s): Three-dimensional partial zona dissection and conventional partial zona dissection were performed. with the use of a simple microneed le, on embryos before preimplantation genetic sampling or on day 3 of embry o development before ET. Main Outcome Measure(s): pregnancy rate, implantation rate. and ease of pre implantation genetic sampling. Result(s): A pregnancy rate of 42% and an embryo implantation rate of 17.6% were obtained in the group in which three-dimensional partial zona dissect ion was performed, compared with a pregnancy rate of 33% and an implantatio n rate of 14.7% in the control group, which underwent conventional partial zona dissection. Preimplantation genetic sampling can be performed without distortion of the blastomere configuration in the embryo. Conclusion(s): Three-dimensional partial zona dissection is a safe: and sim ple mechanical means of creating an opening sufficient for the atraumatic r emoval of material from oocytes and embryos for preimplantation genetic dia gnosis and assisted hatching. (Fertil Steril(R) 1999;71:308-13. (C) 1999 by American Society for Reproductive Medicine.)