Blastocyst culture (BC)and transfer is a technique developed for in vitro fertilization (IVF). This procedure intends to maximize pregnancy rates while minimizing the risk of multiple pregnancies. Embryos are typically cultured for 3 days (cleavage stage with 8-10 cells) before being transferred into the uterus. By extending the culture to 5 or 6 days (blastocyst culture), some embryos will develop to the blastocyst stage (large embryos of 150 cells with a cavity and a cover called trophectoderm & zona).
This allows the embryologist to select more advanced embryos with better potential for implantation at the time of the transfer. Since the implantation rate per embryo is significantly better with blastocyst transfer, one can afford to transfer only one embryo or at the most two embryos and attain satisfactory clinical pregnancy and live birth rates, at the same time avoiding complications of multiple gestation.Blastocyst stage transfer is more physiological, as the endometrium is synchronized with the developmental stage of the embryo.Blastocyst transfer yields a better clinical pregnancy as well as live birth rate, if one considers pregnancy rate per transfer attempt. Another major advantage of blastocyst transfer is its role in patients with previous multiple failed attempts at IVF.In our unit we offer single blastocyst transfer in the first attempt. It is better to freeze all embryos and transfer the embryo in the next cycle, also called frozen thaw cycle. Just prior to freezing, the blastocyst can be geneticallyanalysed using the technique of PGT A (preimplantation genetictesting for aneuploidy). In this the embryo is biopsied. The 3-4 cells of biopsy are sent for geneticanalysis. We have our own in-house genetictesting using the S5 Ian Torrent Next Generation Sequencing. The blastocysts are frozen after biopsy, in single individual straws, which are numbered. The report of NGS comes in 1 -2 months. After two months we can transfer a single euploid (genetically normal) blastocyst and obtain very high pregnancy rate, with singleton pregnancy and low miscarriage rate.
Patients who require pre-implantation geneticdiagnosis for geneticdisorders like thalassemia, sickle cell anaemia, balanced translocation, spinal muscular dystrophy and fragile x syndrome will also need to undergo trophectoderm biopsy, freezing of Blastocyst, testing the cells using NGS and transferring normal embryo in subsequent embryo Transfer cycles. we already have helped few patients of thalassemia and sickle cell anaemia to have normal babies following PGT M.
