Pre-implantation Genetic Diagnosis (PGD) is a procedure used during in vitro fertilization (IVF) to screen embryos for genetic disorders or chromosomal abnormalities before they are implanted into the uterus. PGD ​​allows parents who are carriers of genetic diseases to select embryos that are unaffected by these conditions, thus reducing the risk of passing on genetic disorders to their children. Additionally, PGD can be used for family balancing purposes, where parents choose embryos of a specific sex for non-medical reasons.

Initial Consultation: Couples interested in PGD first consult with a fertility specialist and genetic consultant to discuss their medical history, reasons for considering PGD, and the specific genetic conditions they wish to screen for.

Then the couple undergo the same steps used in IVF (refer to IVF for further details)

1. Controlled Ovarian Stimulation: The woman undergoes ovarian stimulation with fertility medications to produce multiple eggs during her menstrual cycle. Monitoring of the ovarian response is conducted through blood tests and ultrasounds.
2. Egg Retrieval: Once the eggs are deemed mature, a minor surgical procedure called egg retrieval (or oocyte retrieval) is performed under sedation or anesthesia. A needle is guided through the vaginal wall to the ovaries, where the eggs are aspirated.
3. Fertilization: The retrieved eggs are then fertilized with sperm in the laboratory through either conventional IVF or intracytoplasmic sperm injection (ICSI).
4. Embryo Culture: Fertilized eggs are cultured in the laboratory for several days.
5. Embryo Biopsy: One or more cells are removed from each embryo either on Day 3 (cleavage stage) or Day 5 (blastocyst stage) for genetic testing. This biopsy is typically performed using a laser to create a small opening in the embryo’s outer shell (zona pellucida), and cells are then extracted.
6. Genetic Testing: The biopsied cells are analyzed using various genetic testing techniques, such as polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH), to screen for specific genetic disorders or chromosomal abnormalities.
7. Embryo Selection: Based on the results of the genetic testing, embryos free from the targeted genetic conditions or chromosomal abnormalities are selected for transfer.
8. Embryo Transfer: One or two healthy embryos are transferred into the woman’s uterus using a thin catheter. Any remaining viable embryos may be cryopreserved (frozen) for future use.
9. Pregnancy Test and Follow-up: Approximately 12-14 days after embryo transfer, a pregnancy test is performed to determine if implantation has occurred. If successful, the woman continues with prenatal care, leading to the birth of a healthy child.

PGD ​​can offer hope to couples at risk of passing on genetic disorders, as well as those seeking to balance the sex of their children. However, it raises ethical concerns regarding the selection of certain traits in children and the potential for misuse or abuse of the technology. As such, the use of PGD is regulated in many countries to ensure that it is used responsibly and ethically.