How we decide on which day to transfer your embryos

This is a guest post from Dr Saiprasad Gundeti, Senior Embryologist at Malpani Infertility Clinic.

Embryo transfer represents the final stage of the IVF treatment and is the climax of the IVF treatment cycle. How do we decide on which day to transfer your embryos ? Day 1 ? Day 2 ? 3 ? 5 ? Which is better ? and why ?

Unfortunately, human reproduction is not a very efficient enterprise. This is true in the bedroom as well as the clinic, and most embryos do not become babies. This is because many embryos have a genetic error ( which is often random) and will not implant, because Nature will prevent them from doing so. This is why the implantation rate even for top quality embryos is about 40%.

So how do we select the top quality embryo to maximize your chances of success ? And how do we decide which day to transfer it ? And how may do we transfer ? All complex questions, which IVF clinics need to deal with daily !

While some clinics are very rigid about which day they will do the embryo transfer, we are very flexible; and since we offer the entire range of options in our clinic, we try to select the option which will maximize your chances of success .

While there has been a lot of hype about blastocyst transfers, we now believe that if an embryo is going to become a baby, it will, whether we transfer on Day 3 or Day 5 ! Keeping the embryos in the lab for an additional 2 days will not increase their chances of implanting !

There are 2 type of embryo transfer. These are

* ZIFT (ZYGOTE INTRAFALLOPIAN TUBE TRANSFER)
* UTERINE EMBRYO TRANSFER

ZIFT (ZYGOTE INTRAFALLOPIAN TUBE TRANSFER)

* In this procedure, the Embryos are transferred into the fallopian tubes.
* The procedure is done by performing laparoscopy under General Anaesthesia.
* Maximum 4 embryos can be transferred.
* 2 embryos in each fallopian tube, if both the tubes are patent.
* The advantage of a ZIFT over a regular embryo transfer is that it has a higher success rate, because the fallopian tube provide a better in vivo environment for the early embryo than the IVF lab !

Limitations of ZIFT

* Only Day 1 and Day 2 embryos can be transferred by performing ZIFT. With day 3 or blastocyst stage embryos, the risk of an ectopic pregnancy is high.
* Clinics without a OR in which to do a Laparoscopy , cannot perform ZIFT.
* ZIFT requires the presence of an anesthesiologist, since it is done under general anesthesia.
* We cannot perform ZIFT, if the fallopian tubes are blocked.
* It is more expensive.
* Not all IVF experts have the expertise to perform a ZIFT because it requires a higher level of surgical skills.
* It is especially helpful in poor ovarian responders , with few embryos
* It is very useful in patients with cervical stenosis, where a uterine embryo transfer is technically difficult, because it allows us to transfer the embryos directly into the fallopian tubes, allowing us to bypass the cervix.
* You can learn more about ZIFT at www.drmalpani.com/zift.htm

UTERINE EMBRYO TRANSFER

* This is the standard procedure. In this procedure, the Embryos are directly transferred into the uterine cavity.
* The procedure usually does not need Anaesthesia.
* Number of embryos to transfer is decided considering the day on which the transfer is performed.

ON WHICH DAY POST ICSI/IVF, CAN WE PERFORM EMBRYO TRANSFER ?
Generally embryos are transferred on Day 2, Day 3 and Day 5 post ICSI / IVF. Remember that day of egg collection ( also known as DPO = day post ovulation) is Day 0.

HOW DO WE DECIDE ON WHICH DAY TO TRANSFER YOUR EMBRYOS BACK TO THE UTERUS?
There are multiple variables which we consider while deciding when to transfer your embryos back to your uterus.

PRE – EGG COLLECTION

* Number of Follicles developed during superovulation:

More than 10 Follicles –

* Can perform embryo transfer on Day 5
* Can easily transfer your embryos on Day 2 or Day 3
* Can do a sequential Embryo transfer i.e transfer some embryos on day 2 or day 3 and some on day 5.

Less than 10 Follicles –

* Cannot take a decision on transferring your embryos on Day 5
* Can perform your embryo transfer on Day 2 or Day 3
* Cannot take decision on doing a sequential embryo transfer

Less than 5 Follicles –

* Cannot perform your embryo transfer on day 5
* Can perform your embryos transfer on day 3 only if the eggs collected are mature
* Can perform your embryo transfer on day 2

POST – EGG COLLECTION

* Number of eggs retrieved after Vaginal Egg Collection

More than 10 Eggs –

* Can perform your Embryo transfer on Day 5 considering maturity of eggs.
* Can transfer your embryos on Day 2 or Day 3
* Can perform sequential embryo transfer
* Can freeze good quality supernumerary embryos after transferring best embryos on day 2, day 3 or day 5.

Less than 10 Eggs –

* Cannot take decision on transferring your embryos on day 5 before knowing maturity status of eggs.
* Can transfer your embryos on day 2 or day 3
* Cannot perform sequential embryo transfer
* Cannot decide about freezing supernumerary embryos.

Less than 5 Eggs –

* Cannot transfer your embryos on day 5
* Can transfer your embryos on day 2.
* Cannot transfer your embryos on day 3, unless all your eggs are mature
* Cannot freeze supernumerary embryos.

POST – ICSI

* Total number of Mature Eggs (MII) injected

Less than 5 Mature Eggs

* Cannot transfer your embryos on Day 5
* Can transfer your embryos on day 2
* Can perform your transfer on day3, but need to wait to see how many eggs fertilise.
* Cannot freeze supernumerary embryos.

5 – 10 Mature Eggs

* Can transfer your embryos on Day 2 and Day 3.
* Need to wait till Day 2, to take decision on transferring your embryos on Day 5.
* Can freeze good quality supernumerary embryos after transferring the best embryos to your uterus.

More than 10 Mature Eggs

* Can easily transfer your embryos on Day 2 and Day 3
* Can transfer your embryos on Day 5
* Can do a Sequential Embryo transfer.
* Can freeze good quality supernumerary embryos after transferring the best embryos to your uterus.

ON DAY 1 (POST FERTILISATION ASSESMENT)

* Number of Eggs fertilized (i.e. Eggs with 2 pronuclei in them)

1 – 4 2PN –

* Strictly need to transfer your embryos on day 2.
* Cannot transfer your embryos on Day 3 or Day 5.

5 – 10 2PN –

* Can easily transfer on Day 2 and Day 3
* We need to wait till day 2, to take a decision on whether we can transfer your embryos on Day 5. Decision depends upon the quality of the embryos once they start cleaving on Day 2
* Can freeze supernumerary embryos, but need to assess their quality.

More than 10 2PN –

* Can transfer your embryos on Day 2 and Day 3
* Can usually offer the option to transfer your embryos on Day 5
* Can freeze supernumerary embryos.

Embryo Transfer on Day 2 and Day 3


Top quality Day 2 Embryo Top quality Day 3 Embryo

* Day 2 transfer can be considered for all patients.
* Need to have at least 6 embryos on Day 1 to consider transferring embryos on Day 3

Pros

* High number of Supernumerary Embryos can be frozen after transferring the best embryos into your uterus.

Cons

* The chances of success with a Single Embryo Transfer are reduced
* Need to transfer 3 Grade A embryos on Day 2 and at least 2 Grade A Embryos on Day 3, which may lead to multiple pregnancy.

Embryo Transfer on Day 5

Top Quality Day 5 Embryo

* The basic requirement to do a Day 5 Embryo Transfer is that we should get lots of Eggs, as only 40 % of fertilized Eggs make it to Blastocyst stage in vitro
* Embryos which are Top grade on Day 2 have a better chance of forming blastocysts when cultured till Day 5

Pros

* Can consider Single Embryo Transfer effectively.
* Top quality Embryo can be selected to transfer, which will a have high probability of implanting in your uterus.
* Can transfer 1 or maximum 2 Top Quality embryos, thereby reducing the chances of multiple pregnancy.

Cons

* Only 40 % Embryos make it to Day 5. This means patients with few eggs and those with a low fertilization rate cannot be considered for Day 5 Embryo Transfer.
* Low Freezing rate for supernumerary embryos as all Embryos don’t turn out to be top quality on Day 5.