2022년 대한생식의학회 (KSRM) Partial opening of the zona pellucid in vitrified-warmed blastocyst improves clinical outcomes (유리화-해동된 배반포의 투명대를 부분 개방하는것이 임상 결과를 향상시킨다)

Jun-sang Park, Ho Jeong Son, Min Ji Kim, Ga Won Kim, Gyeong Deok Heo, Hye Yoon Kim, Seok Gi Kim, Ji Yun Seong, Hye Kyung Noh, Kyeong Ho Lee
Mamapapa&Baby Ob/Gy clinic, Baby dream research center, Ulsan, Korea- South.

Introduction

Recently, single vitrified-warmed blastocyst transfer is increasingly used as the main strategy for IVF-ET strategy in many IVF laboratories because it has shown results in not only preventing multiple conceptions, but also in improving implantation and pregnancy rates. However, it suggests that this vitrified-warmed method may also cause hardening of the zona pellucida. Even so, this hatching impairment can be overcome by assisted hatching. Escaping through the assisted hatching holes still requires a considerable energy consuming effort from blastocysts and more than 30% blastocysts still failed to hatch from the zona pellucida, resulting in degeneration. Therefore, we investigated whether partial opening of the zona pellcida showed an improvement in clinical outcomes as a method of assisted hatching in vitrified-warmed blastocyst.

Methods

This prospective study was performed Mamapapa&baby Ob/Gyn between January 2018 and august 2022 and included 1,086 vitrified-warmed blastocyst transfers. The partial opening of the ZP was performed in 583 vitrified-warmed blastocyst transfer. As control groups, 503 vitrified-warmed blastocyst was transferred without the partial opening of ZP. The blastocysts were thawed one day before transfer, and the ZP was partially opened immediately after thawing and then cultured.

Results

There were no significant differences in age (35.6±3.8 vs. 35.9±3.9), number of blastocysts transferred (1.0) and other demographics in each group. Total pregnancy rate was 63.1% (685/1086) and ongoing pregnancy rate was 59.6% (618/1086). The pregnancy and ongoing pregnancy rates (70.5 and 64.0%) of partial opening of the ZP group were significantly higher than the rates (54.5 and 48.7%, respectively, P<0.05) of control group. Also, spontaneous abortion rate (9.2%) and monozygotic twin rates (2.2%) in partial opening of the ZP group were lower than those of control group (10.6 and 2.6%, respectively), although a statistical significance was not observed in the difference.

Conclusion

The hatching of blastocysts is important during pregnancy. It is generally known that implantation will fail if the blastocyst does not fully hatch, and hatching through a small hole in the ZP increases the chances of monozygotic twins. In our results, partial opening of the ZP significantly increased the pregnancy rate. In addition, there was no damage to the blastocyst during partial opening in the ZP because the vitrified blastocyst was completely shrinkage. Therefore, partial opening of the ZP would be a more efficient method of assisted hatching to increase pregnancy without worrying about blastocyst damage or monozygotic twins.

한글 요약

유리화-해동된 배반포를 대상으로 한 보조 부화술에서 투명대를 부분 개방하는 것이 임상 결과에 미치는 영향을 조사한 결과, 2018년 1월부터 2022년 8월까지 1,086건의 이식 사례 중 투명대 부분 개방을 시행한 583건이 대조군 503건에 비해 임신율을 유의미하게 증가시켰으며, 이는 배반포의 부화가 임신에 중요하며 투명대 부분 개방이 임신율을 유의하게 높이는 효과적인 보조 부화술 방법임을 입증하여, 착상 실패 및 일란성 쌍둥이 발생 위험을 줄이는 데 기여할 수 있음을 제안한다.