Thinning and drilling laser-assisted hatching in thawed embryo transfer: A randomized controlled trial

Area of Science:

• Reproductive Medicine
• Embryology
• Assisted Reproductive Technology

Background:

• Hardening of the zona pellucida (ZP) in frozen-thawed embryos can impede implantation.
• Laser-assisted hatching (LAH) is a technique used to improve pregnancy rates by facilitating embryo hatching.
• Comparing different LAH methods is crucial for optimizing frozen embryo transfer (FET) outcomes.

Purpose of the Study:

• To compare the efficacy of ZP thinning versus ZP drilling for LAH in FET cycles.
• To evaluate the impact of ZP thinning and drilling on key pregnancy indicators.
• To determine if patient age or ZP thickness influences the effectiveness of either LAH method.

Main Methods:

• A randomized controlled trial involving 171 FET cycles after in vitro fertilization/intracytoplasmic sperm injection.
• Patients were assigned to either ZP thinning (removing 25% circumference, 50% thickness) or ZP drilling (creating a 40 µm hole).
• LAH was performed on day 2 after embryo thawing.

Main Results:

• No significant differences were observed between thinning and drilling LAH groups in terms of β-human chorionic gonadotropin-positive rates, implantation, clinical pregnancy, miscarriage, ongoing pregnancy, or multiple pregnancy rates.
• Pregnancy outcomes remained comparable between the two LAH methods across subgroups based on maternal age (<35 or ≥35 years) and ZP thickness (<17 µm or ≥17 µm).

Conclusions:

• Both partial ZP thinning and drilling are equally effective LAH techniques for improving implantation and pregnancy rates in FET.
• The choice between ZP thinning and drilling does not appear to be influenced by patient age or initial ZP thickness.
• LAH, through either thinning or drilling, offers similar benefits for thawed embryo transfer success.