A policy of sequential or consecutive transfer on Day 3 and Day 5 embryos in patients with adequate number of retrieved oocytes, yields the advantages of a good embryo implantation rate, satisfactory pregnancy rate and an acceptable multiple pregnancy rate at the same time avoiding complications of blastocyst transfer like cancellation of the transfer cycle and higher multiple order births. However, the results of this approach depend on the number of fertilized oocytes and the quality of the fertilized embryos. Thus, sequential transfer approach has the advantage of blastocyst transfer without exposing the whole cycle to the risk of cancellation.
Under the assumption that embryos that cease to develop in utero, result in implantation failure, growing them to the blastocyst stage will serve two goals. First, it will enable better selection of embryos for transfer and second it will promote more physiologic synchronization with the endometrium and capability of achieving the “implantation window”.
However, it is possible that no blastocyst forms during culture with the risk of cycle cancellation. So this is an approach that is only suitable for patients who produce many embryos. The rationale behind sequential embryo transfer is that, during the first day-3 transfer, the embryos (1 or 2 embryos) may induce an increase in endometrial receptivity, thereby creating a better endometrial environment for the second transfer (1 blastocyst) on day 5. Our unit is specialised in this technique. We get many patients from all over India and world, who have failed multiple times outside with other doctors . We use this technique and achieve pregnancies in most of them.
Sequential embryo transfer involves transfer of cleavage(day 3) and blastocyst (day 5) The preparation for transfer in frozen cycles will start from day 2 or day 3 of period. Your lining and ovaries will be evaluated using a transvaginal ultrasound
Cleavage stage transfers were popular in the past but it has now shifted to a blastocyst transfer. There is an increased success with blastocyst transfer as it a natural selection from the cohort that grows further. This also comes with the worry of no embryos that have reached the blastocyst stage and hence there is nothing to transfer, hence to overcome this the concept of sequential transfer has been made.
The cleavage embryo also increases the receptivity of the endometrium.