Most methods of determining which embryo to transfer to the uterus during In Vitro Fertilization rely on a visual assessment under the microscope. The prettiest embryo wins. Unfortunately, this approach ignores the most common cause of IVF failure – chromosomal abnormalities. Doctors can’t tell by simply looking at an embryo whether it is chromosomally “competent.” If an embryo has too many or too few chromosomes, it will either fail to develop, result in a miscarriage, or be manifest as a birth defect.
Until recently, the only method available for analyzing the number of chromosomes in an embryo was a process called FISH (Fluorescence In Situ Hybridization). The problem with FISH is that it only analyzes 8-12 of the 23 chromosome pairs in an embryo. This leaves more than half of the chromosomes unaccounted for and therefore falls short as a reliable method of embryo selection.
The recent introduction at Sher Institutes for Reproductive Medicine (SIRM) of a remarkable new technology called CGH (Comparative Genomic Hybridization) now allows analysis of every pair of chromosomes in the embryo for numerical abnormalities. Starting in 2007, we performed several studies applying this technology to the IVF process to select “competent” embryos, and the results were remarkable. To date, several hundred of our patients have undergone IVF using this method and more than 60% have achieved pregnancies! This is about twice the national average per embryo. For the past 5 years, we’ve been researching the most efficient and reliable methods for performing this highly complex test, and have put a network of resources in place to achieve what we believe to be the most accurate CGH testing available in the world.