Fortunately, improvements in Assisted Reproductive Technology for fertility care occur constantly. In this article we update providers and patients on an important development which offers the ability to screen the embryo for genetic diseases carried by the parents and to screen for chromosomal abnormalities in the embryo.
This will ultimately decrease the miscarriage rate and increase the chance to have a healthy baby through IVF or Egg Donation. Additionally, 2 new instruments are presented which allow us to offer improved pregnancy outcomes with IVF and Egg Donor.
Preimplantation Genetic Screening (PGS) and Diagnosis (PGD) – change in biopsy and transfer procedures
1. What is the difference in Preimplantation Genetic Screening and Preimplantation Genetic Diagnosis?
Preimplantation Genetic Screening (PGS) and Diagnosis (PGD) are both used to perform genetic testing on biopsied cells taken from embryos during an IVF cycle. During PGS, embryos are screened for changes in chromosome numbers, whether a translocation/inversion or aneuploidy. All 23 pairs of chromosomes may be screened at one time.
With PGD, embryos may be tested and diagnosed for a specific disease such as Cystic Fibrosis, Tay-Sachs, or Spinal Muscular Atrophy. Most genetic diseases that have been identified by a study of the parents for a gene mutation can be tested for with PGD.
2. How has the procedure changed?
Previously a blastomere was biopsied from a 6 – 8 cell cleavage stage embryo on day 3 of culture and the blastomere was sent to a diagnostic lab. Results were received, and 1 - 2 normal embryo(s) were transferred to the patient’s uterus on day 5 of culture at the blastocyst stage.
Currently, several cells are biopsied from the 100 or more cell embryos at the blastocyst stage on day 5 of culture. The blastocyst is then cryopreserved with vitrification and stored until results are received.
The patient then undergoes a frozen embryo transfer (FET) cycle at her convenience where the normal embryo(s) is warmed and transferred in an attempt at pregnancy.
3. What are the advantages to the new procedure?
Since the blastocyst has many more cells than the cleavage stage embryo, multiple cells are removed and processed as compared to 1, sometimes 2, blastomeres. A larger amount of cells for diagnosis means more accurate results.
Mosaicism is reportedly lower at the blastocyst stage as compared to the cleavage stage embryo, thereby increasing the chance that results are representative of the rest of the blastocyst.
Even though each blastomere of a cleavage stage embryo is totipotent, cells biopsied from the blastocyst are trophectoderm cells, which are extra-embryonic tissue, thus the inner cell mass of the blastocyst is not manipulated – it is this tissue that becomes the baby.
A laser is needed to perform the biopsy on the trophectoderm cells and is used to prepare the embryo on day 3 of culture. The laser is much easier to use than the previous methods using mechanical and chemical means.
Performing the embryo transfer in a non-stimulated FET cycle may be advantageous as compared to the stimulated IVF cycle.
A higher percentage of patients will potentially receive a single embryo transfer leading to fewer high-risk pregnancies.
4. Will PGS or PGD increase a woman’s chances of pregnancy?
The chance for delivery of a healthy baby will be increased with the use of PGD, and will vary with the use of PGS with each unique situation.
5. What does a couple need to know before PGS or PGD is performed?
A couple should make an appointment with their fertility specialist to discuss PGS or PGD. The process for PGD is more involved than PGS.
With PGD, a formal consultation with a genetics counselor is indicated and a customized genetic marker will be designed by the diagnostic lab prior to the IVF/PGD cycle. A marker is not required for PGS testing.
Should you have questions about PGS or PGD, please call the ART Fertility Program of Alabama’s scheduling department at 205-870-9784 to schedule an appointment with a physician.
New incubator systems
1. What is an incubator?
The incubator is one of, if not the, most important piece of equipment in the IVF Lab. The incubator provides a stable environment for the developing embryo during IVF procedures.
In order to optimize embryo growth and clinical outcome, the incubator functions to control temperature, gas concentrations and humidity, as well as reduce environmental stresses.
2. How does the new G185 differ from a typical incubator?
The G185 is smaller and has individual chambers for each patient. Water is not required as the incubator functions without humidity. Gas cylinders are easily connected providing the carbon
dioxide and low oxygen environment desired. Each chamber contains a stainless steel plate heated to 37⁰ centigrade. This creates a compartmentalized system.
1. Does the G185 provide a better environment for embryos?
Maintaining the embryos in a more compartmentalized system provides a better environment by limiting exposure of embryos to the room environment when entering the chamber and quicker recovery of temperature, gas concentration and pH.
2. Will Art Fertility’s patients benefit from this G185?
Due to the better temperature and gas stability, along with the compartmentalized, low oxygen environment of the G185, ART Fertility’s patients will benefit from this new technology.
Thus far we have seen an increase in embryo quality leading to more embryos available for transfer and vitrification and a trend towards an increase in pregnancy rates.
New Laser – Saturn 5 by Research Instruments
1. What is a laser?
The Saturn Laser uses a high-powered ablation laser and a visible pilot laser transmitted through fibre optics. The Saturn has sub-micron accuracy with a computer controlled laser. An Exclusion ZoneTM ensures safety of the cells by establishing an area of lowest laser pulse near critical areas.
2. What is the laser used for in the IVF Laboratory?
The Saturn Laser is used to introduce an opening in the zona pellucida (ZP), the outside covering of the embryo. This procedure is referred to as Laser Assisted Hatching or LAH in lab terms.
LAH may be indicated during an IVF cycle for the following: advanced maternal age, recurrent implantation failure, elevated FSH or P4, poor embryo quality including embryos with thick ZP, and frozen-thawed embryos or oocytes.
Spontaneous hatching of the embryo from the ZP is a necessary event prior to implantation of the embryo in the uterus. Creating an opening in the embryo’s ZP is thought to facilitate implantation for those embryos considered to have trouble implanting due to hardening of the ZP or lack of spontaneous hatching.
Another use of the laser is to collapse the blastocyst, the 5 or 6 day old embryo, prior to cryopreservation by vitrification. The blastocyst is characterized by an inner cell mass, the trophectoderm cells, and the fluid filled blastocoel cavity. By lasering the junction between two trophectoderm cells, the blastocoel cavity will collapse, causing the fluid to leave the cavity.
Vitrification has been found to be more successful after removal of fluid from the blastocyst. Research has indicated an increase in blastocyst implantation following laser collapse of the blastocyst prior to vitrification.
3. What benefits have you seen from this new technology?
Results with the Saturn Laser thus far in our program have shown a trend towards a higher implantation and/or ongoing pregnancy rate when LAH and/or collapsing is utilized.
4. How will ART Fertility’s patients benefit from this new laser?
The improvement in implantation and pregnancy results should allow patients a higher chance to have a baby with IVF.
At ART Fertility of Alabama, we are excited about these new additions to our laboratory. These new developments in Assisted Reproductive Technology for fertility care will increase the chances to have a healthy baby through IVF or Egg Donation, and we are thrilled to offer this to our patients.