Comprehensive Chromosomal Screening (CCS)
Definition - What does Comprehensive Chromosomal Screening (CCS) mean?
Comprehensive chromosome screening (CCS) is a type of preimplantation genetic screening, which uses in-depth analysis to select the most promising embryos for transfer during an in vitro fertilization (IVF) procedure.
CCS uses a technique that measures the number of chromosomes present in an embryo, identifying the normal, healthy specimens ideal for conception. This process significantly lowers the risk of implantation failure or miscarriage, 70% of which is caused by the chromosomal makeup of an embryo.
FertilitySmarts explains Comprehensive Chromosomal Screening (CCS)
IVF begins with a series of ovarian stimulation medications, used in assisted reproductive treatments (ART) to induce the production of multiple eggs during one ovulation cycle. Access to multiple eggs increases the odds of producing a healthy specimen, ideal for transfer to the uterus. Once the eggs are fertilized by a sperm sample, the embryo remains in the lab for around 5 days. During this time, the embryo is both developing and under observation.
The CCS is conducted by removing several cells from each of the embryos, and conducing in-depth analysis on their chromosomal composition. An embryo that develops with too many or too few chromosomes is called an aneuploidy. An aneuploidy is a significant cause of failed IVF due to implantation failure or miscarriage. If a pregnancy does survive, children born with an abnormal number of chromosomes can have genetic conditions that in some cases are serious and life threatening, including:
- Trisomy 21 or Down syndrome
- Turner syndrome
- Williams syndrome
- Klinefelter syndrome
Once the analysis has been completed, the scientists can recommend which embryos are ideal for transfer.
Aside from lowering the risk of genetic disorders, CCS also reduces the risk of a multiple pregnancy. Typically, multiple embryos are transferred as a contingency against one or more failing. However, the confidence provided by the CCS results may increase the appeal of a single transfer.
CCS may not be a standard component of every IVF procedure. However, it is often recommended for women or couples with the following considerations:
- Advanced maternal age of 35 or older
- History of repeated pregnancy loss
- Previous pregnancy with a chromosomal abnormality
- History of multiple failed IVF cycles