Why my embryos may have chromosomal pathology?
About 70% of embryos (both in natural pregnancy and after ART treatment) cannot be realized in a birth of a baby due to miscarriage of pregnancy or disruption of implantation process. The main reason is chromosomal abnormalities (called “aneuploidy”), caused by loss or presence of an extra chromosome or its part.
What are the methods of preimplantation diagnosis?
Today the following methods are used for aneuploidy screening in preimplantation diagnosis:
- FISH-analysis (aneuploidy screening of embryos for 9-12 chromosomes in patients who are the carriers of chromosomal rearrangements);
- Comparative genomic hybridization(aneuploidy screening of embryos for all chromosomes in patients – carriers of chromosomal rearrangements in cases of multiple failed IVF attempts and habitual miscarriage with normal karyotype of embryos).
What is comparative genomic hybridization?
Comparative genomic hybridization (CGH) – is a modern method of molecular genetics that can diagnose aneuploidy and microstructural chromosomal rearrangements simultaneously in all chromosomes.
- is a thousand times more sensitive than standard cytogenetic methods;
- reveals violations that are invisible on routine karyotyping;
- allows to do assessment of all chromosomes simultaneously;
- provides clear identification and quantitative characterization of the anomaly.
How can my embryos be investigated?
“Nadiya” performs research of elastomers and cells of trophectoderm:
- Research of blastomeres- the cells of the embryo on day 3 of development. The study characterizes the embryo, but does not exclude the possibility of mosaicism (when the embryo cells may have different chromosomal set).
- Research of trophectoderm cells – cells that form the outer shell of the embryo. The study describes the embryo including the possibility of mosaicism. However, the analysis is performed on day 5 of embryo development, requiring its freezing at the study period (1-3 days) and further use in the Frozen cycles of ART. The choice of tactics of diagnosis is determined individually in every case based on the history of infertility, state of the mother’s health, embryos and their number.
ART – assisted reproductive technology.
FISH – fluorescent in situ hybridization.
CGH –comparative genomic hybridization.
The purpose of CGH – «One embryo-one child” The use of preimplantation diagnosis in CGH aims to:
- increase the number of successful IVF cycles;
- reduce the number of multiple pregnancies (by transferring fewer but qualitative embryos);
- reduce the incidence of spontaneous, miscarriage of pregnancy.
And what if there is no “normal” embryo…?
There is some possibility that no embryo is good enough for transfer. There are multiple reason for this; all of them can be defined for each individual case only by a doctor. Then the doctor will decide on the further scheme of the treatment. Please, note that “Nadiya” under no circumstances will perform the transfer of aneuploidy embryos.
It is established that the risk of false results after CGH diagnostics is less than 1%. However, we recommend conducting further prenatal diagnosis at the early term of pregnancy for accurate results.
Features of pregnancy after preimplantation diagnosis
Preimplantation genetic diagnosis does not give absolute guarantees for successful pregnancy even after screening of all chromosomes, as the reasons for not bearing can be compromised immune status or undiagnosed pathology. In general, pregnancy after preimplantation diagnosis is can have the same risk factors as the natural pregnancy. Meanwhile, thousands of children around the world were born with the use of preimplantation diagnosis.