3dt vs 5dt?

I was wondering what you guys know about a 3dt vs 5dt?
Is one better than the other?

Re: 3dt vs 5dt?

This is very interesting

Blastocyst - an embryo that has developed to the stage where it has two different cell types and a central fluid-filled cavity. The surface cells, called the trophectoderm, will become the placenta, and the inner cells, called the inner cell mass, will become the fetus itself. Blastocyst formation in the human usually occurs on the 5th day after fertilization.

A healthy blastocyst should hatch from its outer shell, called the zona pellucida by the end of the sixth day. Within about 24 hours after hatching, it should begin to implant into the lining of the mother's uterus.

Implantation rate - the percentage of embryos transferred to the woman that end up implanting and continuing development. If we transfer 4 embryos that results in a singleton pregnancy then the implantation rate was 25%.

The ultimate goal of in vitro fertilization (IVF) and embryo culture is to provide high quality embryos which are capable of continued normal development and result in live births. However, under standard IVF culture conditions, only about 20-40% of human embryos will progress to the blastocyst stage after 5 days of culture. This low rate of embryo development is the result of a less than optimal culture environment for the embryos. For this reason, embryos are usually transferred into the uterus after only 2-3 days of culture.

One problem with this is that 2 to 3-day-old embryos are normally found in the fallopian tubes, not in the uterus. The embryo first moves into the uterus at about 80 hours after ovulation. The implantation process begins about 3 days later - after blastocyst formation and hatching have occurred. Therefore, if in vitro culture conditions could be improved so that blastocysts formed at a higher rate, then embryos could be placed into the uterus at the blastocyst stage - at a more "natural" time, and shortly before implantation should occur.

Transferring blastocysts following IVF also provides another benefit - reduction of the possibility of multiple pregnancy. Some 2 or 3-day-old embryos do not have the capacity to become high quality blastocysts and a viable pregnancy. However, on day two or three of culture we do not have reliable methods to determine which embryos will be viable long-term. By culturing embryos to the blastocyst stage we have more opportunity to choose the most competent ones for transfer. We may then be able to transfer fewer embryos and obtain an equivalent pregnancy rate with less risk for multiple pregnancy.

It is generally very difficult to get good numbers of high quality blastocysts with current culture conditions. New culture media are currently being developed and tested that might allow higher blastocyst formation rates. This could make blastocyst transfer a viable option for all IVF programs in the future.

One option to improve blastocyst formation rates that is currently available is coculture. The basic concept involves growing embryos on top of a layer of cells rather than directly on the bottom of a plastic culture dish. Various types of cells have been used, such as fallopian tube cells or cells from the lining of the uterus (endometrial cells). IVF with coculture has been utilized in animal in vitro embryo culture systems for over 30 years. More recently it has also been used in some human IVF laboratories. The concept behind coculture is that these cells, which are sometimes referred to as "feeder" cells or "helper" cells, help to stimulate the development of the embryos.

Coculture is labor-intensive and, unless the cells are obtained from the woman having IVF, there is at least a theoretical concern regarding transmission of infectious disease (viruses, etc.) from the cells to the embryos or to the patient. New culture media are now available that allow high blastocyst formation rates without the use of coculture.

Results

Day 3 transfers had a 30% implantation rate and a 66% "clinical pregnancy rate".

Day 5 transfers had a 51% implantation rate and a 71% "clinical pregnancy rate". This was the case even though 2 patients in this group had their embryos arrest at the 8-cell stage and therefore had no embryo transfer at all, and 2 more patients had no blastocysts, but had morulas transferred and became pregnant.

Message edited 3/16/2007 10:10:42 AM.

Re: 3dt vs 5dt?

It's one of the great running debates of IVF.

Some doctors swear you get better results waiting until 5 days because they can tell which ones are the healthiest.

Some doctors believe that the 3 day is best because the uterus is the best possible place for them to thrive so they are more likely to make it to 5 days.

So there is very little consistancy in what is done and why.

I personally had a 5 day transfer. But that's also because I had 11 eggs.

They seem to be more likely to wait until the 5 day when you have more eggs to choose from.

Re: 3dt vs 5dt?

I also think it depends on your age. My RE told me He would really only consider 3dt because I am over 35

Re: 3dt vs 5dt?

Re: 3dt vs 5dt?

Thanks so much!!!
This makes sense. I am waiting for my call back to see if I do 3 or 5dt right now!!

Re: 3dt vs 5dt?

My RE told me not to concern myself too much with a 3d or 5d transfer. He said that the reason a 5dt is preferred is because they put back fewer embryos than they would in a 3dt therefore resulting in a lower rate of multiples. He also said that yes it's good to get a blastocyst (5dt) but that doesn't mean that a 3dt that wouldn't grow in the lab would have died before 5 days in the womb. Some embroys do better in their natural environment.

Also I had a 5dt but I had 28 eggs retrieved. Out of the 28 eggs 18 fertilized, we transferred 2 blasts and we had 0 to freeze. Good Luck!

Re: 3dt vs 5dt?

i did 5dt because i did pgd (genetic testing on the embryos). the first time it didn't work and the 2 blasts they put in, didn't stick. then for the fet, the 2 blasts did stick, so who knows!!