What is the probability that there will be no embryos left after the PGT?

The probability of having no embryos suitable for transfer depends on several factors such as age, ovarian reserve, DNA fragmentation:

• Decreased Ovarian Reserve: in these patientes fewer oocytes are retrieved. Ovarian reserve and ovarian response are inversely related to maternal age; as maternal age increases, both ovarian reserve and response decrease. Consequently, advanced maternal age affects the number of oocytes retrieved, their quality, and the number of embryos available for biopsy.
• Reduced Embryo Yield: a lower starting number of oocytes translates to fewer embryos reaching the blastocyst stage suitable for biopsy. Is important to understand that biopsy for PGT can only be performed on blastocysts; if embryos arrest earlier, they cannot be analyzed.
• Increased Aneuploidy: oocytes from patients with advanced maternal age have a higher risk of chromosomal abnormalities (aneuploidy), further reducing the percentage of "healthy" embryos available for transfer.

Another factor to consider is the quality of the sperm:

• Male factor: high sperm DNA fragmentation can negatively affect the genetic quality of embryos.

If you (or your partner) are a carrier of a structural rearrangement or a monogenic disease, the risk of not having embryos available after PGT will also depend on the probability, in each individual case, of having embryos free of the mutation, and on whether you choose to have them analysed for aneuploidies as well.

In summary, the greater the number of embryos available for PGT, the higher the chances of obtaining healthy embryos suitable for transfer to the uterus.