, Volume 29, Issue 11, pp 1159-1166
Date: 05 Oct 2012

A review of, and commentary on, the ongoing second clinical introduction of preimplantation genetic screening (PGS) to routine IVF practice

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Abstract

Purpose

Current re-introduction of “improved” preimplantation genetic screening (PGS#2) raises the question whether PGS#2 is ready for routine clinical application.

Methods

We assessed available evidence via review of published data for years 2005–2012, and review of currently ongoing registered clinical trials, based on searches under appropriate key words in PubMed, MEDLINE, Cochrane Database System Review and Google Scholar and http://www.ClinicalTrials.gov. In absence of prospective clinical trials, and due to limited available data, individual publications/ongoing studies are assessed.

Results

PGS#2 offers significant improvements in accuracy of aneuploidy diagnosis over PGS#1. By moving embryo biopsy from day-3 after fertilization (6–8 cell stage) to trophectoderm biopsy at blastocyst stage (day 5–6), PGS#2, however, adds additional co-variables to the analysis of efficacy of the procedure, which have special relevance for women with diminished ovarian reserve (DOR), who usually produce small egg and embryo numbers. Limited published data, claiming efficacy of PGS#2, as well as ongoing clinical trials, do not consider these additional co-variables, do not analyze outcomes by intent to treat and, therefore, have to be considered biased in patient selection.

Conclusions

Here reached conclusions are based on absence of adequate data rather than affirmative outcome assessments. They, therefore, are subject to change at any future date with generation of significant new data. Premature introduction of PGS#1 caused significant damage to patients. As currently no reliable PGS#2 data are available to suggest improvements in IVF outcomes, to avoid a repeat of the PGS#1 experience, PGS#2 should be considered experimental until data show otherwise.

Norbert Gleicher and David H. Barad contributed equally to the work.

Capsule

Though the current re-introduction of preimplantation genetic screening (PGS) involves greatly improved aneuploidy testing of embryos, currently available data do not demonstrate outcome improvements for in vitro fertilization (IVF). Until such data become available, PGS, therefore, should be considered an experimental procedure.