Frozen Embryo Transfer
The “Natural Method” relies on the woman’s ability to produce her own egg which leads to the natural production of the female hormone oestrogen vital for building up the endometrial lining necessary for implantation. For women who do not produce egg naturally, as with Polycystic Ovaries (PCO), a small dose of stimulatory hormones may be required.”Artificial Method” is reserved for women who have a lot of difficulty in producing their own eggs as with severe PCO. Oestrogen tablest are then used to develop the endometrium lining rather than relying on the woman’s natural hormones.
Monitoring for FET is by transvaginal ultrasound scanning and/or using ovulation prediction test. Once the ovulation is detected, the frozen embryos are replaced 2 – 3 days later. On the day of embryo transfer, frozen embryos will be removed from the liquid nitrogen storage tank and thawed to resume its bioactivity. Embryo quality will be assessed after the thawing process and only embryo with good survival rate which indicated with at least 75% intact blastomeres will be chosen for transfer. The embryo transfer procedure for frozen-thawed embryos is as in a conventional embryo transfer. After embryo transfer, patient will be given progesterone hormone pessaries to support the endometrium lining. Success Rate (Pregnancy Rate) with Embryo Cryopreservation.
Embryos can be frozen at various development stages, the 2PN stage, the 4-cell stage, the 8-cell stage or the blastocyst stage. Of all these stages, only 4-cell stage embryo cryopreservation technique is well established and most successful. Only embryo survives the rigorous freeze / thaw process with at least 75% intact blastomeres has great chance to produce pregnancy.