The natural process of embryo development begins with the fertilization of the egg in the outer aspect of the fallopian tube. As the newly formed embryo develops, it moves slowly toward the uterine cavity where it will ultimately implant. This process takes approximately six to seven days.

What is Blastocyst?

5th day embryo is known as Blastocyst, where it is ready to hatch and implant.

What is Blastocyst culture?

Blastocyst culturing is a technique to grow embryos beyond the third day of culture. Previously embryos were transferred into the uterus about three days after the egg retrieval.

Over the years, improved culture environments have allowed us to culture the embryos for two additional days. During this additional culture period, the embryos continue to grow to become blastocysts. When the embryo reaches the blastocyst stage, it is ready to hatch and implant.

Why is Blastocyst culturing done and what are the advantages of it? 

Blastocyst allows optimal selection of good quality embryos for transfer and therefore

  1. Increased implantation rate per embryo transferred.
  2. Reduces the miscarriage rate.
  3. Overall, it may not necessarily increase your chance for pregnancy
  4. Eliminate the possibility of multiple pregnancies, while maintaining a high pregnancy rate.
  5. Reduces the number of abnormal embryos being frozen.
  6. It reduces the number of total embryo transfer cycles and total number of embryos transferred. 

What are the drawbacks of blastocyst freezing?

  1. 10% of patients won't have an opportunity for embryo transfer due to the absence of blastocyst development.
  2. Increased cost for blastocyst culture.

Blastocyst transfer may also increase the chance of having identical twins.

Who are more suitable to have blastocyst transfers?

Generally, women who are younger, who can produce a good number of eggs after ovarian stimulation, have a good number of good quality cleavage stage embryos, and a good chance of getting pregnant, will be recommended a blastocyst transfer.

Generally speaking, this procedure should be limited to patients with excessive numbers of embryos usually more than five, in which case further selection of embryos beyond the day three stage would be advantageous.

What is the normal blastocyst formation rate?

For younger patients, up to 50% of all embryos will continue to grow to the blastocyst stage. However, 10% of patients won't have an opportunity for embryo transfer due to the absence of blastocyst development. As patients get older, fewer and fewer numbers of embryos are capable of developing in culture to the blastocyst stage.