Introduction to Genetic Screening & Course Plan

The Foundation – Why Genetic Screening Matters

Genetic screening has revolutionized reproductive medicine by moving us from a paradigm of chance to one of informed choice. The primary clinical goal is to identify embryos with the correct chromosomal makeup, thereby increasing the likelihood of a successful, healthy live birth and reducing the risk of miscarriage or genetic disorders. In the context of surrogacy, where intended parents often have a single surrogate cycle, maximizing the efficiency and success potential of each embryo transfer is paramount. This module establishes the core objectives of genetic screening: improving implantation rates, reducing time to pregnancy, and minimizing genetic risk.

Types of Genetic Screening – A Clinical Toolkit

Not all genetic screening is the same. We utilize different tools for distinct clinical questions.

• Preimplantation Genetic Testing for Aneuploidy (PGT-A): This test assesses embryos for chromosomal aneuploidy – an abnormal number of chromosomes. Aneuploid embryos (e.g., Trisomy 21/Down syndrome, or missing a chromosome) are the leading cause of implantation failure and miscarriage. PGT-A allows us to select a euploid (chromosomally normal) embryo for transfer.

• Preimplantation Genetic Testing for Monogenic Disorders (PGT-M): For intended parents known to be carriers of a specific genetic condition (e.g., Cystic Fibrosis, Huntington’s disease, Sickle Cell Anemia), PGT-M screens embryos for that particular disorder. This prevents the transmission of hereditary conditions to the child.

• Carrier Screening: This is a blood test performed on the intended parents before pregnancy. It identifies if they are carriers for recessive genetic conditions. If both partners are carriers for the same condition, there is a 25% chance with each pregnancy of having an affected child. This knowledge allows us to proactively plan for PGT-M.

The PGT-A Process – From Biopsy to Report

The PGT-A pathway is a coordinated effort between the IVF lab and the genetics laboratory.

1. IVF & Blastocyst Culture: Embryos are created via IVF and cultured for 5-7 days until they reach the blastocyst stage.

2. Trophectoderm Biopsy: A highly skilled embryologist safely removes a few cells from the part of the blastocyst that will become the placenta (the trophectoderm). This does not harm the inner cell mass, which becomes the fetus.

3. Cryopreservation: The biopsied embryo is immediately vitrified (flash-frozen).

4. Genetic Analysis: The biopsied cells are sent to a specialized lab for comprehensive chromosomal screening using Next-Generation Sequencing (NGS).

5. The Report & Clinical Decision-Making: The report classifies embryos as Euploid (normal), Aneuploid (abnormal), or Mosaic (a mix of normal and abnormal cells). This result is the single most critical factor we use to decide which embryo to transfer, prioritizing the euploid embryo with the highest morphological grade.

Interpreting Results & Navigating Complex Findings

Understanding the lab report is crucial.

• Euploid Embryos: These are the preferred candidates for transfer, offering the highest chance of a healthy, ongoing pregnancy.

• Aneuploid Embryos: These embryos are not recommended for transfer as they typically result in failure or miscarriage.

• Mosaic Embryos: This is a nuanced finding. Mosaic embryos contain a mix of euploid and aneuploid cells. The decision to transfer a mosaic embryo depends on the specific chromosome involved and the percentage of abnormal cells. This requires extensive genetic counseling with the intended parents to weigh potential risks and outcomes.

Genetic Screening in the Surrogacy Journey

In a surrogacy arrangement, genetic screening is a powerful tool for risk mitigation and success optimization.

• Maximizing Cycle Success: By transferring a single, vetted euploid embryo to the surrogate, we achieve the highest possible chance of a healthy singleton pregnancy, protecting the surrogate’s health and fulfilling the intended parents’ goals in the most efficient manner.

• Providing Certainty: For all parties involved—intended parents, surrogate, and medical team—the knowledge that the embryo has been screened provides significant psychological reassurance and reduces anxiety.

• A Collaborative Standard: At Surrogacy4All, we integrate genetic screening as a standard of care in our curated journeys, ensuring that every medical decision is data-driven and focused on delivering a healthy baby.