Comprehensive chromosomal screening (CCS) is a type of genetic testing used in IVF cycles that helps determine if embryos are aneuploid – have an incorrect number of chromosomes, or euploid – are chromosomally normal. With CCS, a few cells are removed from the trophectoderm of a day 5 embryo, known as a blastocyst, and biopsied. The trophectoderm contains cells that will develop into the placenta, rather than cells that will develop into the fetus. The chromosomally normal embryos are frozen and later transferred in a frozen embryo transfer.
In a retrospective cohort study, Colorado Center for Reproductive Medicine compared perinatal outcomes of singleton infants conceived with and without CCS to understand the impact of trophectoderm biopsy on the developmental future of resultant pregnancies. The study found that, “The majority of deliveries occurred at term and there was no difference in infant gender between groups. Mean gestational age and birth weight were comparable between the groups. In fact, the incidence of very preterm birth and large for gestational age was reduced in the CCS group.” The study concluded, “Babies born after CCS present with excellent perinatal growth and health outcomes.”
“I think it’s an important study to look at live birth and obstetrical outcome of the babies because people early on questioned that while the biopsy screens for chromosomal errors, would it actually lead to other birth defects, and it appears that’s not the case,” says Dr. William Schoolcraft, Founder and Medical Director of the Colorado Center for Reproductive Medicine.
According to Schoolcraft, CCS is often recommended in the following cases:
- Women who have had recurrent miscarriage
- Women with a prior pregnancy involving a chromosomal abnormality
- Women who have multiple failed IVF cycles