P-494: A second check for excluding tripronuclear zygotes

Abstract

Multipronuclear zygotes in human in-vitro fertilization (IVF) programmes can be seen in all fertilized oocytes. The most of multipronuclear zygotes are triploid. The aim of the study is describing the fertilized zygotes as two pronuclei (2 PN) in the first pronuclei check ∼ 16-18 hours after sperm injection and discarding zygotes defined by the formed from 2 PN to three pronuclei (3 PN) ∼ 4-5 hours after the first check. Retrospective clinical study. One hundred ninety-nine intracytoplasmic sperm injection (ICSI) patients between 20-44 ages participated in this study. Sixteen to 18 hours after ICSI, oocytes were checked for the precense of pronuclei under the inverted microscope (X 200).The presence of two clearly visible pronuclei was considered as normal fertilization. 2 PN zygotes were checked again ∼ 4-5 hours after the first check by the same embryologist. Some of the zygotes that were seen 2 PN in the first check were defined as 3 PN in the second check. Intracytoplasmic sperm injection was performed to 2037 oocytes. The overall fertilization rate was 74 % and the rate of polyploidy was 1 %. The 27 of the 1380 (2 %) 2 PN zygotes were developed as 3 PN zygotes. Also embryo transfer was cancelled in one patient who had only one zygote because the zygote defined by the development of 3 PN in second check. If control was not done twice, the embryo developed from 3 PN zygote would be transferred. The differences between triploid and diploid embryos may not remaind apparent and normal cleavage stages might be observed. Therefore, tripronuclear zygotes are excluded from replacement in IVF programmes, so in this study 3 PN zygotes that were developed later were discarded as the second assessment of 2 PN zygotes. Hence, the second check is recommended not to overlook late onset 3 PN zygotes .