Early Cleavage Embryos and Their Infl uence on theConventional IVF Outcome

Overview

Objective:
To assess if early cleavage embryo is an additional indicator of embryo quality thatcould be used to increase the effi ciency of IVF and ET.Design: A prospective study.Setting: Centre for Assisted Reproduction, Department of Gynecology and Obstetrics, MedicalFaculty, Palacký University, University Hospital, Olomouc.Methods: The study evaluates 62 cycles of conventional IVF in our Centre during 2001 to 2002. All embryoswere observed for the presence or absence of ”early cleavage” (EC), i. e. with completed fi rst mitoticdivision 25 to 26 hours after insemination. The EC embryos were cultivated separately from the so called”late cleavage” or no early cleavage (NEC) embryos. After the three-day cultivation a maximum of threeembryos were transferred in 6-8 cells stage. EC embryos were transferred in 28 cycles, NEC embryos in18 cycles. The remaining 16 patients with ”combined” transfer of EC + NEC embryos were excluded fromthe evaluation. The following parameters have been compared: age, number of fertilized oocytes, fertilizationrate (FR), number of cryopreserved embryos, number of embryos assessed for EC, number of ECembryos found, number of transferred embryos, pregnancy rate (PR), implantation rate (IR), spontaneousabortions (AB). Statistical analysis was performed by Student’s t-test, χ2 test and Sheffe analysis.Results: EC embryos were found in 71% of conventional IVF (n=44). There were no signifi cantdifferences in the entry parameters (age, number of fertilized and fertilizing oocytes, number ofcryopreserved, assessed and transferred embryos) between the group with EC embryos versusthe group with NEC embryos. When EC embryos were transferred, the following parameters werehigher: PR (61% vs. 56%), IR (38% vs. 33%), compared to NEC group, while pregnancy loss waslower after EC (4% vs. 11%) compared to NEC. Due to small numbers in the subgroups the results,though suggestive, are not statistically signifi cant (p>0.05).Conclusions: The assessment of early cleavage embryo is one of the criteria for evaluation andselection of suitable embryos prior to transfer which could help in the process of selection tochoose the best embryos between embryos of the same morphology on the day of transfer.

Key words:
”early cleavage” embryos, selection of embryos, quality of embryos, viability of embryos,IVF