What Is Comprehensive Chromosome Screening (CCS)?

By (embryologist) and (fertility counselor).
Last Update: 02/11/2015

The spontaneous abortion rate of blastocyst transfer without conducting a preliminary analysis in women between 38 and 41 years of age is 42%, but may decrease until 0% thanks to the transfer of an embryo previously analyzed by chromosomal screening (CCS), which allows all 23 chromosome pairs to be analyzed.

New screening technique

According to the study “RCT study in advanced maternal age patients using array-CGH: interim analysis”, these tests improve the embryos implantation rate because they are able to assess the viability of these embryos prior to their transfer to the womb.

According to Carmen Rubio, as maternal age increases so does the risk of appearance of aneuploidies , that is, changes in the number of chromosomes. Carmen Rubio is the director of the Preimplantation Genetic Diagnosis for Chromosome Abnormalities program in IGENOMIX. During the European Society of Human Reproduction and Embryology (ESHRE) Congress, in Munich, Rubio said it is vital that the embryos are screened before they are transferred. This screening allows normal embryos to be chosen, reducing the risk of abortion and of babies with chromosomal abnormalities.

Chromosomal screening

The study was based on the analysis of a group of women aged between 38 and 41, whose embryo was subjected to a preliminary analysis of possible anomalies, while another control group had no such treatment during blastocyst transfer. The researchers were able to detect a percentage of 81 abnormal embryos in the groups. This result reflects the importance of this pre-transfer analysis, notes Dr. Rubio.

Exams that detect aneuploidies are useful tools that allow the analysis of the embryo viability in cases of women who decide to be mothers later in life and in cases of couples with fertility problems. This chromosomal screening may help to improve the clinical results of assisted reproduction treatments.

The main conclusion is that, thanks to this new technique, aneuploidies can be ruled out before implantation occurs, allowing only healthy embryos to be transferred, something that's not possible with FISH, the usual technique for preimplantation genetic diagnosis.

Some abnormalities such as trisomies are capable of evolving to highly advanced embryo stages, maintains Marta Ariza, a biologist at IVI Madrid. Although there is a clear relationship between the quality of blastocyst and aneuploidy, the embryo should be analyzed using the new technique of CGH arrays (Chromosomal Screening) that allows to avoid the transfer of this kind of embryos.

The development of chromosomal Screening exams is a valuable tool to determine the chromosomal status of the embryos produced by IVF or ICSI techniques, thus preventing miscarriages due to chromosomal causes, and therefore reducing abortion rates .

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 Laura Garrido
Laura Garrido
B.Sc., M.Sc.
Bachelor's Degree in Biotechnology from the Pablo de Olavide University (UPO) of Seville, Spain. Master's Degree in Biotechnology of Human Assisted Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI). Experience at IVF, andrology, and general analysis laboratories. Embryologist specialized in Assisted Reproduction. More information about Laura Garrido
Adapted into english by:
 Sandra Fernández
Sandra Fernández
B.A., M.A.
Fertility Counselor
Bachelor of Arts in Translation and Interpreting (English, Spanish, Catalan, German) from the University of Valencia (UV) and Heriot-Watt University, Riccarton Campus (Edinburgh, UK). Postgraduate Course in Legal Translation from the University of Valencia. Specialist in Medical Translation, with several years of experience in the field of Assisted Reproduction. More information about Sandra Fernández

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