Clinical Management of In Vitro Fertilization With Preimplantation Genetic Diagnosis

Ilan Tur-Kaspa, M.D.

Disclosures

Semin Reprod Med. 2012;30(4):309-322. 

In This Article

Elective Single Embryo Transfer and PGD

Multiple pregnancies are a major iatrogenic complication of ART, and elective single embryo transfer (eSET) has been suggested and implemented as the best strategy to prevent it. In some countries it is imposed by legislation and in others by guidelines and regulations of professional societies. Compared with double embryo transfer (DET), eSET is effective in significantly lowering twin pregnancy rates by 94%. However, it also significantly reduces the likelihood of live birth by 38%.[110,111] Nevertheless, evidence from RCTs suggests that increasing the number of eSET attempts (fresh or frozen) results in a cumulative LBR similar to that of DET.[110]

When postthaw survival and implantation rates of cryopreserved surplus blastocysts biopsied for PGD are comparable with the postthaw survival and implantation rates of nonbiopsied embryos, eSET with potential future frozen ETs should be recommended to young women undergoing PGD. These results were demonstrated for embryos that were biopsied either on day 3 or day 5 regardless of whether they were cryopreserved by slow freezing methods or by vitrification.[112–117] We at IHR/RGI[112] have been offering eSET to all patients <36 years since 2004, and when top-quality embryos are available for transfer, pregnancy rates were not compromised.

The group of de Boer et al,[118] from Sydney IVF, was the first to suggest moving to blastocyst biopsy for PGD/PGS with SET to reduce the rate of multiple pregnancies. They have shown that blastocyst biopsy on day 5 or 6 with cryopreservation allowed embryos to be electively thawed and transferred one at a time later on.

Donoso et al[48] demonstrated in a retrospective study that SET after PGD does not significantly reduce the deliver rate for women <36 years of age. They compared the outcome of SET PGD cycles from 2003 to 2005 versus DET PGD cycles from 2001 to 2003. Although only 37% of patients undergoing SET had more than one embryo available for transfer (eSET), the delivery rates were 27.4% in the SET group and 34% for the DET group (p = NS). Although the SET pregnancy rates were from a later period and may have been affected by improved ART outcome generally observed during these years, this study still demonstrated that implementing SET for PGD significantly reduced the multiple pregnancies without affecting the delivery rate. El-Toukhy et al[115] described similar findings, experiencing a significant decrease in multiple pregnancies in the fresh PGD cycles (from 36% to 10%) with no reduction in pregnancy rates after implementing an eSET policy and cryopreservation of the extra embryos.

In summary, vitrified cryo-thawed biopsied embryos after PGD may reach a survival rate and implantation rate comparable with embryos with no biopsy. eSET should be offered to young women undergoing PGD or PGS, especially when top-quality embryos are available.

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