The effect of zona thinning size on implantation and pregnancy rates of ICSI-ET patients with advanced woman age

Objective: To find if the zona thinning size (in length) of the embryos transferred had any effects on the implantation and clinical pregnancy rates.
Design: A prospective randomized study
Setting: Infertility and Assisted Reproductive Techniques Centres.
Material methods: Sixty infertile women (≥38 years old) who underwent ICSI-ET procedures and accepted to join this study were enrolled. Women were assigned as one in 25 µm and the following in 50 µm zona thinning size groups consecutively, according to the order of the transfers. Thirty patients were assigned in each of the groups. Zona thinning procedure without perforating the zona was performed on the embryos before transfers, using a novel zona laser treatment system.
Main outcome measures: Implantation and clinical pregnancy rates.
Results: Implantation rates were 0.087±SD 0.160 and 0.099±SD 0.156 (p>0.05), and clinical pregnancy rates were 7/30 (23.3%) and 8/30 (26.7%) (p>0.05), in 25 and 50 μm zona thinning size groups, respectively.
Conclusion: Increasing the zona thinning length up to twice the commonly used size did not have any significant effects on the implantation and clinical pregnancy rates in women with advanced age who underwent ICSI-ET treatment.

Keywords
Clinical pregnancy rate, implantation rate, hatching, zona thinning size, ICSI.