The effect of laser-assisted thinning and laser-assisted drilling techniques on assisted reproductive outcomes

To compare the effect of two different assisted hatching laser protocols thinning assisted hatching laser (TAH) vs drilling of assisted hatching laser (DAH) and non-assisted hatching control group (NAC) on clinical pregnancy and live birth rates in frozen thawed cleavage stage embryo transfer cycles.

This study included 310 infertile patients who underwent frozen embryo transfer (FET) cycles from 2021 to 2022 at the ART Unit of the Medical Point Hospital of Izmir University of Economics, Izmir. Patients included in the study were those between 20 and 40 years of age, who had undergone frozen-thawed embryo transfer after 'freeze-all' protocols. The exclusion criteria were azoospermia and degenerated embryos. In TAH, laser thinning was performed by making 4-5 shots at a depth of 50% of the thickness of the zona pellucida (ZP). In DAH, the laser opening was made from the outer part of the ZP to the inner part. In the last group in NAC, assisted hatching was not performed. Clinical pregnancy and ongoing pregnancy rates were compared between the TAH, DAH and NAC cycles.

There was no difference in terms of the age of the woman, the BMI and the sperm parameters in the three groups. There were no statistical differences between the groups in terms of the number of oocytes, embryos and the quality of the transferred embryos. Clinical pregnancy in thinning assisted hatching laser (TAH), drilling of assisted hatching laser (DAH), non-assisted hatching control group (NAC) cycles (38% vs 39% vs 45% p = 0.842, respectively.), ongoing pregnancy (34% vs 32% vs 39%; p = 0.670, respectively.) and live birth rates (34% vs 29% vs 35,4%; p = 0.586, respectively) were similar in three groups.

In conclusion, no significant differences were found between the TAH, DAH and NAC groups in terms of ART outcomes.