VIDEO: Comparative Genome Hybridization (CGH) Changes the IVF Playing Field

7 years ago

IVF is still mostly a game of chance. Sperm are released near the egg in a dish to compensate for the long passage into the uterus. You can go a step further in taking some control by utilizing procedures such as ICSI, where a single sperm is injected into the egg. And even deeper than that, PGD can be used to screen embryos for certain genetic disorders, ensuring that only embryos that are not affected will be transferred back to the uterus.

But that's where our human limits end because it's up to the body to either accept or reject the embryo since implantation cannot be manipulated. Until recently.

Human chromosomes coloured light micrograph. Each chro- mosome comprises two identical chromatids linked at a region called the centromere. Centromere also divides each chromatid into long and short arms. Chromosomes are found in the nuclei of cells. They only appear like this during cell division. Chromosomes contain the DNA deoxy-ribonucleic acid that provides instructions for growth development & functions of the organism. Most cell nuclei have 46 chromosomes 23 from each parent.

Fine, so implantation still can't be manipulated, but not since the advent of PGD has there been an advancement on the IVF front that has made such an enormous difference. A somewhat new test, called comparative genomic hybridisation (CGH), can screen for abnormalities that sometimes occur as embryos divide, which allows a doctor to know the viability to an embryo prior to transfer. In other words, doctors have a new tool in addition to the current embryo grading system used during IVF with a concrete reason for the embryo they're transferring back to the uterus. They will transfer back the embryos which have the greatest chance of developing into a fetus rather than embryos with genetic abnormalities that are likely to be lost in the first trimester.

Before you get your knickers in a twist over this, please understand what I mean by genetic abnormalities. I am speaking about errors that occur in the cell division that are not compatible with life. The majority of pregnancy loss occurs within the first trimester and the majority of these losses are due to abnormalities in the embryo. If the cell is missing chromosomes during the division, the embryo will fail to grow. The film below best explains the process of cell division.

News of the test's success rates from an on-going study were released in the United Kingdom, on the same day that the research was being presented as ASRM's conference in San Francisco. In the United Kingdom, single embryo transfers (SET) are commonplace and government regulated. "The researcher who has developed the new technique is planning to offer it in the UK for about £2,000, on top of the fee for IVF, and around the same as standard screening techniques."

The same system of SETs has been suggested in America, though the reason many Americans do not opt for a SET is the high costs associated with IVF in America. It is easier to take a chance and transfer one embryo when the government is subsidizing the cost. It is much harder to place all of your hope on a single embryo when you are paying over $10,000 for each cycle. Unless there was a way to ensure that the embryo chosen had a high chance of implanting and being carried to term, barring other female factor issues such as a clotting disorder.

The benefits of moving to a SET system is clear--fewer transferred embryos equals fewer multiple births. Singletons are the ideal outcome in an IVF cycle and this test helps raise the chance of success from a SET--up to "78% of the 23 women who underwent the treatment."

Bloggers Who Know About CGH

Way Too Much Information used CGH on the frozen embryos from their 8th IVF cycle and discovered they had only one viable embryo. They did another cycle and got another embryo out of it and soon, she will have her frozen transfer.

Empty Vessel got a positive after a cycle where she used CGH. She had a son last fall.

A Journey to Conception has a post about CGH and the benefits of it.

Have you ever used CGH on an IVF cycle? What are your thoughts on the test?

Melissa writes Stirrup Queens and Lost and Found. Her book is Navigating the Land of If.

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