Laser-assisted zona pellucida thinning may negatively effect pregnancy outcome of frozen-thawed embryos Conference Paper uri icon


  • O-259 – Laser-assisted zona pellucida thinning may negatively effect pregnancy outcome of frozen-thawed embryos I. Har-Vardi1, M. Friger2, A. Zeadna1, S. Alboteano1, D. Richter1, T. Priel1, G. Alter1, G. Bar1, I. Bord1, A. Harlev1, L. Man1, E. Lunenfeld1, E. Levitas1 1Soroka University Medical Center, Dept. of Obstetrics & Gynecology, Beer - Sheva, Israel; 2Ben-Gurion University of the Negev, Dept. of Epidemiology, Beer - Sheva, Israel Study question: Can laser-assisted hatching of the zona pellucida (ZP) positively effect pregnancy outcome of frozen-thawed cleavage stage embryos? Summary answer: Performing assisted hatching (AH) on frozen-thawed cleavage stage embryos prior to ET in women above 35 years was shown to reduce clinical pregnancy rate, to increase chemical pregnancy and missed abortion rates. No significant effect of AH was shown regarding those parameters in women below 35 years. What is known already: Hatching of the embryo through the zona pellucida is a necessary step for successful implantation. AH, a laser opening in the ZP has been proposed as a method for improving embryo implantation. Controversy exists regarding the effect of AH on frozen-thawed embryos on clinical pregnancy, implantation and delivery rates. The most relevant conclusion obtained so far is that AH in fresh cycles has a beneficial effect in women with repeated embryo implantation failures. Study design, size, duration: A retrospective study included 334 patients that underwent frozen-thawed embryo transfer between 2012 and 2013. AH was performed on embryos of 170 patients in 2012. We compared IVF outcomes: chemical and clinical pregnancy rates, implantation, abortion and delivery rates according to age groups above/below 35 years. Participants/materials, setting, methods: The data were divided into 4 groups according to women's age and laser-AH performance; group 1 – below 35 years (245) and group 2 over 35 (89). AH performance: group 1a – below 35 (118) and group 2a- over 35 years (52). Statistical analysis was carried out using t-test and Chi-Square Tests. Main results and the role of chance: No differences were found between AH/no AH groups regarding clinical pregnancy rate, chemical pregnancy rate, implantation rate, missed abortion rate and delivery rate in women below age 35 (mean age 28.5±3.41). Surprisingly, performing AH in women above 35 years (mean age 38.6±2.6) was shown to reduce clinical pregnancy rate (9.6% vs 23.3%), P<0.05, to increase chemical pregnancies (11.5% vs 0), P<0.05 and to increase missed abortion rate (0 vs 44%), P<0.05. No differences were found between the groups concerning other confounding variables which could effect implantation and pregnancy rate. There were no differences in implantation and clinical pregnancy rates in the fresh cycles between the years 2012–2013. Limitations, reason for caution: This study was carried out retrospectively. Patients were compared between cases and controls that were recruited in consecutive years (cases 2012 control 2013). To exclude bias, only cycles of frozen-thawed cleavage embryos (48-72 hours) were included. Blastocysts were excluded from the study because of the thinner zona pellucida. Wider implications of the findings: Performance of AH was suggested to improve the outcome of frozen thawed embryo transfer because of ZP hardening during the freezing and thawing process. However, our data shown that in cycle of frozen-thawed cleavage stage embryo transfer, AH in women over 35 years, could decrease IVF outcomes. In frozen-thawed cycles we would recommend to transfer the embryos with no further involvement. The potential value of AH for frozen-thawed embryos has to be weighed carefull

publication date

  • January 1, 2015