OBJECTIVE: To evaluate whether a second biopsy, following a first diagnostic failure on blastocysts tested for preimplantation genetic testing for monogenic diseases (PGT-M), allows to obtain genetic diagnosis and to what extent this procedure can influence clinical pregnancy and live birth rates compared to the PGT-M process with a successful genetic diagnosis from the first biopsy.
METHODS: Embryos from women who underwent PGT-M in an infertility centre and who had been transferred after two biopsies for genetic analysis (n = 27) were matched in a 1:1 ratio accordingly to women\'s age (± 1 year) and fertility status (fertile vs infertile), as well as with the study period, with embryos who were transferred after receiving a conclusive PGT result straight after the first biopsy (n = 27). The main evaluated outcome was clinical pregnancy rate following embryo transfers in which healthy embryos were transferred after only one biopsy and those in which an embryo was transferred after being re-biopsied. Live birth rate was the secondary outcome.
RESULTS: Clinical pregnancy rate was 52% (95% CI: 34-69) following the transfer of a single-biopsy blastocyst and 30% (95% CI: 16-48) following the transfer of a re-biopsied blastocyst. The likelihood to have a healthy baby was 33% (95% CI: 19-52) following the transfer of a blastocyst biopsied once and 22% (95% CI: 11-41) following the transfer of a re-biopsied blastocyst.
CONCLUSIONS: The re-biopsy intervention seems to considerably reduce the pregnancy potential of a blastocyst. However, a greater sample size is necessary to clarify this issue definitively.

OBJECTIVE: The objective of this virtual study was to simulate a full cycle and assess the costs and benefits to a couple with a reciprocal translocation, using current techniques for preimplantation genetic testing and comparing reporting every chromosome with only reporting those involved in the rearrangement.
METHODS: A simulation was constructed for women under the age of 35 years, where vitrified-warmed embryos were transferred one at a time in a first full cycle following preimplantation genetic testing using next-generation sequencing and sampling the trophectoderm at the blastocyst stage. The effect on pregnancy outcomes (live birth, clinical miscarriage and biochemical pregnancy) was evaluated for different reporting strategies for embryo transfer to (i) report only the rearranged chromosomes and transfer embryos with a normal or balanced test result for the translocation (targeted), or (ii) report every chromosome and exclude from transfer all embryos with an abnormal test result (exclusion), or (iii) exclude only those consistent with an unbalanced translocation and/or unrelated non-mosaic whole-chromosome aneuploidy and assign those with samples consistent with a normal or balanced translocation complement and unrelated mosaic aneuploidy or segmental imbalance (embryos of uncertain reproductive potential) a lower transfer priority (ranking). The number of individual women whom might benefit by avoiding an adverse pregnancy outcome (biochemical pregnancy, clinical miscarriage) or be disadvantaged by not achieving a live birth was evaluated. The financial cost of the different reporting strategies and the time taken to complete a cycle were also considered.
RESULTS: The simulation showed that compared to only reporting the translocation chromosomes (targeted reporting), testing every chromosome and ranking embryos by test result for transfer was a cost-effective strategy to avoid an adverse pregnancy without compromising the chance of a live birth. Excluding from transfer embryos with a test result consistent with a normal or balanced translocation complement of uncertain reproductive potential was an inferior strategy because it resulted in fewer live births from a full cycle. Reporting only the translocation chromosomes was an inferior strategy because it was less effective than ranked reporting of every chromosome to avoid an adverse pregnancy. Compared to targeted reporting, the ranked and exclusion strategies marginally reduced the overall cost and time taken to complete a full cycle. The ranking strategy avoided 1 adverse pregnancy for 12 cycles started, compared to 1 in 10 for the exclusion strategy which also resulted in 1 in 22 fewer women achieving a live birth. A minority (< 10%) of couples benefited by avoiding at least 1 adverse pregnancy whilst also reducing the time and cost for a complete cycle; most (> 70% ) couples received no benefit additional to targeted reporting and had the same outcome for pregnancy, time and cost.
CONCLUSIONS: The primary objective of PGT-SR for couples with a reciprocal translocation is to avoid a pregnancy with a chromosomally unbalanced product of the translocation and to reduce the risk of miscarriage, at least to that expected for couples with normal karyotypes. Trophectoderm sampling at the blastocyst stage with testing using NGS is an effective approach; however, ranking and excluding from transfer embryos with abnormal test results for unrelated chromosomes is problematical and is likely to be detrimental to achieving a live birth. Targeted reporting, where only the results of the chromosomes involved in the translocation are known, should be preferred to achieve a live birth. A best effort should be made to follow up and investigate all pregnancies following PGT-SR. Once the reproductive outcome is known (biochemical pregnancy, clinical pregnancy, live birth), the chromosomes unrelated to the rearrangement can be analysed as an experimental study. The risk/benefit of avoiding an adverse pregnancy vs reducing the chance of a healthy delivery should be a decision for each individual couple and informed by appropriate genetic counselling for their specific translocation and history.