Timing embryo biopsy for PGD – before or after cryopreservation?

Abstract

Objective: Pre-implantation genetic diagnosis (PGD) is required in order to screen and diagnose embryos of patients at risk of having a genetically affected offspring. A biopsy to diagnose the genetic profile of the embryo may be performed either before or after cryopreservation. The aim of this study was to determine which biopsy timing yields higher embryo survival rates.

Study design: Retrospective cohort study of all PGD patients in a public IVF unit between 2010 and 2013. Inclusion criteria were patients with good-quality embryos available for cryopreservation by the slow freezing method. Embryos were divided into two groups: biopsy before and biopsy after cryopreservation. The primary outcome was embryo survival rates post thawing.

Results: Sixty-five patients met inclusion criteria. 145 embryos were biopsied before cryopreservation and 228 embryos were cryopreserved and biopsied after thawing. Embryo survival was significantly greater in the latter group (77% vs. 68%, p < 0.0001).

Conclusion: Cryopreservation preceding biopsy results in better embryo survival compared to biopsy before cryopreservation.

Chinese abstract

目的: 植入前遗传学诊断(pre-implantation genetic diagnosis, PGD) 被用于筛查、诊断具有下一代遗传病高风险的患者的胚胎。用于诊断基因图谱的胚胎活检可在冻存前或冻存后进行。本研究的目的在于确定在哪个时间取活检可以获得更高的胚胎存活率。研究设计: 前瞻性队列研究2010至2013年所有就诊于IVF治疗中心的PGD患者, 纳入标准为胚胎质量高, 可进行胚胎的慢速冻存。胚胎分为2组: 冻存前取活检、冻存后取活检。主要观测指标为冻融后的胚胎存活率。结果: 共入组符合纳入标准的患者65名。冻存前活检的胚胎145例, 冻融后活检的胚胎228例。后者的胚胎存活率明前高于前者(77% vs. 68%, p < 0.0001) 。结论: 冻存后进行胚胎活检的胚胎存活率高于冻存前胚胎活检。

Keywords:

• Biopsy
• blastomere
• cryopreservation
• embryo
• freeze
• PGD
• slow

Declaration of interest

All authors report no conflict of interest and this research was non-funded.