I am excited to announce the birth of the first baby in Southern California early this week as a result of In Vitro Fertilization (IVF) using a genetically tested and frozen egg by comparative genomic hybridization (CGH) (See the announcement at www.prnewswire.com)
After treating the first CGH cases in Southern California with IVF for infertility, I am excited by the fact that we now have the option of screening all mature eggs for chromosomal abnormalities. This will allow women to freeze their eggs for whatever reason it may be and give them the confidence and reassurance that they have chromosomally normal eggs to use in the future.
The success rate depends on whether the eggs are chromosomally normal at the time of egg freezing. It is impossible to determine the genetic abnormalities of the eggs without testing and CGH test appears to be the most promising technology so far with the most number of cases done in the world. If the eggs are genetically abnormal at the time of freezing, the outcome is expected to be negative when they are thawed and fertilized in the future.
How Do We Freeze Eggs and Test Them Genetically?
The ovaries are stimulated with hormones (FSH and LH), eggs are matured and aspirated similar to the first part of IVF treatment. Once the eggs are determined to be mature eggs (M2) under the microscope, the chromosome bundle called the polar body is removed and analyzed for chromosomal abnormalities using the CGH test. At that time, eggs are frozen using the advanced technique called vitrification or ultra-rapid freezing.
The polar body is the excessive genetic material that the egg releases at the time of ovulation and the mirror image of the egg chromosomally. Using this technique, we are able to determine if the egg is chromosomally normal without destroying the egg for genetic analysis. When pregnancy is desired, chromosomally normal egg(s) are thawed, fertilized and embryo(s) are transferred into the uterus.
CGH testing is also helpful for couples with infertility undergoing IVF treatment who desire to screen their embryos for chromosomal abnormalities. It can be utilized to differentiate and diagnose whether the egg or the sperm is the contributing factor to infertility. Eggs can be screened and only chromosomally normal eggs can be used to create embryos. By controlling for the most important variable, which is the genetic makeup of the egg, the problems attributed to other variables can be treated appropriately.
The risk of multiple pregnancy can also be significantly reduced using this technology because a single CGH tested chromosomally normal embryo can be transferred into the uterus with high success rates. Twin pregnancy (identical twins) may result from splitting of the embryo, but this is rather an uncommon occurence. The risk of triplet pregnancy and other high order multiples are non-existent.