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Updated: Jun 12, 2026
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FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
Improving FISH diagnosis for preimplantation genetic aneuploidy screening
1PGD Unit, Institut Universitari IVI-Valencia, Plaza Policía Local, 3, 46015 Valencia, Spain. pmir@ivi.es
Human Reproduction (Oxford, England)
|May 22, 2010
Summary
Additional hybridization rounds in preimplantation genetic screening (PGS) significantly improve diagnostic accuracy. This method increases the identification of chromosomally normal embryos, enhancing the effectiveness of fertility treatments.
Area of Science:
- Reproductive Medicine
- Genetics
- Embryology
Background:
- Preimplantation genetic screening (PGS) routinely analyzes nine chromosomes using fluorescence in situ hybridization (FISH).
- Additional hybridization rounds are employed for non-conclusive results and to confirm aneuploidies.
- The study aimed to assess the impact of these extra rounds on FISH accuracy.
Purpose of the Study:
- To evaluate the effect of additional hybridization rounds on the accuracy of preimplantation genetic aneuploidy screening (PGS).
- To determine if re-hybridization improves the diagnostic yield of chromosomally normal embryos for transfer.
Main Methods:
- Retrospective analysis of FISH data from 1000 PGS cycles.
- Embryos with non-conclusive results or observed aneuploidies underwent additional hybridization rounds.
- A subset of chromosomally abnormal embryos were re-analyzed on Day 5.
Main Results:
- Re-hybridization of 2477 embryos led to 59% being diagnosed as normal, 40.1% as abnormal, and 0.9% remaining non-informative.
- Confirmation rates for monosomies improved significantly after re-hybridization (80.5% confirmed).
- Day-3 and Day-5 diagnosis concordance increased when re-hybridizations were included, particularly for monosomies (95% vs 82.7%).
Conclusions:
- Additional hybridization rounds enhance the accuracy of PGS diagnostic results.
- This improved accuracy increases the availability of chromosomally normal embryos for transfer.
- Implementing re-hybridization with additional probes as a standard PGS approach can maximize the technique's benefits.
