Whenever IVF or ICSI is performed, embryos may be cultured for either one day, two days, or even five days, before transferring them back into the woman. In order to culture the embryos for five days, i.e. to what we call the "blastocyst" stage, you need to use "sequential" culture media systems. We have used such a system since the summer of 1997 because it gives us the option of culturing the embryos for as long as is clinically appropriate for each particular patient's situation.

However, there is a great deal of debate, and some considerable commercial hype, centering around whether to culture for two days, three days, or five or six days. The media we use, and which many other of the best programs use, allows us to culture the embryos to whatever number of days is appropriate for the particular patient. Since this media is commonly available, it should not be used to hype any particular program.

For some patients with poor quality embryo development (a condition which is programmed into the genome of many infertile women), even with the best culture media, the embryos may be better off going directly into the fallopian tube immediately. For the average patient, day two or day three transfer either to the fallopian tube or to the uterus may be best. For some patients, day 5 transfer to the uterus may be a good option. The problem with extended culture to day 5 is that there may be a loss of some embryos that might have "made it" if they had been transferred earlier.

A well-developed 5-day blastocyst.

The major advantage (despite the already mentioned disadvantage) of day 5 transfer is embryo selection. The implantation rate per day 5 blastocyst transfer is greater than for transfer of day 2 or 3 embryos. But only 20 percent to 50 percent of day 2 embryos can develop in vitro to day five no matter how perfect the in vitro culture system. There is a potential loss therefore of what could have been viable embryos. So selection is the only advantage of blastocyst culture, and this selection has nothing to do with the "quality" of the baby, but rather just whether the embryo "makes it" or not to becoming a baby.

Either way, because our system of embryo freezing is so good, we do not lose anything if we transfer less embryos to reduce your risk of triplets or quadruplets, and just save the extra embryos for a later pregnancy. We can even transfer just one embryo at a time (if that is your wish) without at all reducing your chance of pregnancy.

Therefore, hype should be removed from this issue, and decisions should be made that are in the best interest of the particular patient's situation.

Nonetheless we believe that use of sequential culture media, as we routinely do, is an advantage, in that patients can have the option of prolonged embryo culture if that is in their best interest.