Preimplantation Genetic Diagnosis (PGD) and Preimplantation Genetic Screening (PGS) are the two commonly used terms when it comes to fertility treatments, but are equivocally interpreted as the same. The two solve different purposes and are conducted to examine different genetic problems.

What is the difference between PGD and PGS?

First talking about PGD, it is a diagnostic process that involves screening single cell in the embryo and evaluating it for any possibilities of genetic anomalies or chromosomal disorders.
PGS is a screening technology drawn from PGD that mainly examines if the cells present in an embryo have abnormal number of chromosomes, thus reducing the chances of pregnancy failure.

What can medical experts identify through the process of PGD?

• Presence of any chromosomal translocations (chromosomal rearrangements)
• Single-gene disorders, the prime reason for genetic diseases
• Revealing the sex of the embryo before it is placed into the uterus ( gives couples an option of family planning, bringing gender diversity in their children)

Preimplantation Genetic Diagnosis
Preimplantation Genetic Diagnosis

What can medical experts identify through the process of PGS?

• Chromosomal abnormalities such as the condition characterized by having more or less than the desired number of chromosomes, commonly known as aneuploidy. This condition leads to the increased risk of miscarriages, and therefore, PGS can help in mitigating the chances
• To help with the transfer of chromosomally normal embryos, leaving behind the abnormal embryos

How is PGD performed?

• PGD is performed in congruence with In-Vitro fertilization (IVF) before the embryo transfer process takes place, and pregnancy period begins. It includes egg retrieval and fertilization under controlled environment of a laboratory
• The process begins with removal of embryos through a microscopic needle, and after cell collection the embryos are frozen
• DNA of the collected cells is then examined to determine genetic anomalies
• Normal embryos are placed in the uterus and a positive pregnancy test is expected from the patient
• The process takes weeks as it is carried out in intervals during the entire cycle of an embryo formation

How is PGS performed?

• The process begins when the mother starts taking prescribed medications to encourage egg growth
• Eggs are retrieved through a microscopic needle (transvaginal) in a laboratory. The retrieved eggs are then fertilized by male sperm through a process called ICSI
• A biopsy is then taken from each embryo, where the healthy ones are sieved before proceeding for an embryo transfer. If additional chromosomally normal (healthy) embryos are available, they can be cryopreserved (frozen) if a future embryo transfer is necessitated

Patients can avail the customized bundle plans or go for either of the two screening procedures depending upon the medical expert’s discretion. The procedures can help majorly in determining the gender of your child, and mitigate any genetic predisposition of abnormalities the parents might have, that could be passed down to the offspring.