Many patients who have been through an in vitro fertilization (IVF) cycle have blastocysts that have been frozen. These blastocysts are cryopreserved by a process known as vitrification, which is a highly successful method of cryopreservation, with survival rates of about 98%.
Once the embryos have been vitrified, they can stay in that state indefinitely until a patient is ready to try to achieve a pregnancy.
In many cases, patients with cryopreserved blastocysts have had a successful outcome with the fresh cycle. There are also instances where a pregnancy was achieved, however, the pregnancy resulted in a miscarriage. And unfortunately some patients, despite having embryos with a good morphological grade, do not achieve a pregnancy with the fresh cycle.
The question we often get in all of the above scenarios is, “Can we do chromosomal testing on the embryos that we currently have frozen at your clinic in order to improve the likelihood of a successful outcome?”
The answer, in simplest terms, is yes.
As awareness of preimplantation genetic screening (PGS) grows, more patients want to take advantage of the option to genetically test blastocysts that have been previously frozen. Reasons for wanting to test frozen blastocysts include:
The patient has had a successful pregnancy and wishes to electively transfer a single embryo to avoid multiples. By screening the blastocysts prior to transfer, we improve the likelihood that a single embryo will implant.
Patients who have had a successful pregnancy and wish, for purposes of family balancing, to test the frozen embryos for gender before doing the transfer.
Patients who have had an early miscarriage due to genetic abnormalities and wish to test their frozen embryos prior to transfer to decrease the chances of having to go through another pregnancy loss.
Patients who have had multiple embryo transfers without a successful pregnancy. By testing the embryos, it will give us additional information as to why implantation may not be successful and also help to pick the embryo most likely to create a viable pregnancy.
In other cases, patients may have done PGD and results were unable to be obtained from the cells that were sent. In this instance, thawing, biopsying, and refreezing the embryo is a viable alternative to discarding the embryo or just doing the transfer without any genetic results. A recent study suggests that the majority of embryos with no diagnosis after genetic screening are diagnosed as normal when rebiopsy and reanalysis is performed.
Liza has been an embryologist at InVia Fertility Specialists since 2002. She completed her studies, first in animal science at Southern Illinois University, followed by clinical embryology/reproductive genetics at Eastern Virginia Medical School. Her interests include reproductive genetics, fertility preservation, and mitochondrial function in the human oocyte. She loves being a part of helping others achieve and experience the joy of becoming a parent. Seeing the end result .your baby.makes all the hours in the lab worth it!