Embryo transfer is a part of In vitro fertilization and is the final step in this process. It is a process that involves transfer of the fertilized eggs (embryo) in to the woman’s uterus.

Embryo transfer is a simple procedure and usually does not require anaesthesia. Before the embryo transfer takes place the uterus is prepared by giving oestrogen and progesterone medications. When the endometrial thickness is ready and your progesterone hormones are within range, the embryo transfer date is decided. The embryo transfer is done by the guidance of pelvic ultrasound. A fine embryo transfer catheter is used to place the embryos beyond the cervix and in to the uterus. Once the transfer is done you will be advised to rest for 15 min and there will be a wait period of 14 days before the pregnancy test is done.

Embryo transfer can be fresh or frozen embryo transfer and Day 3 or Day 5 embryo transfer. The number of embryos transferred is debatable. It can be single embryo or multiple embryos.

Fresh embryo transfer: After the retrieval of eggs and its fertilization with the sperms the embryo transfer is performed immediately within the next 3-5 days without freezing them. With fresh embryo transfer there is no wait period and the pregnancy results will be known within a month of start of an IVF cycle. However, fresh embryo transfer cannot be performed if the serum progesterone levels are elevated or if there is risk of ovarian hyperstimulation syndrome. It is also observed that the hormonal injections which are given during ovulation stimulation affects the implantation of the embryo.

Frozen embryo transfer: Frozen transfers are the most commonly employed transfers these days. In this type, once the eggs are retrieved and embryos are formed, they can be cryopreserved in liquid nitrogen for a period of at least 10 years. When the uterus is ready the embryo/s are thawed and transferred inside the uterus.

Frozen embryo transfer allows the added advantage of having a more suitable hormonal environment, doing a pre-implantation genetic testing of embryos and if more embryos are formed it can be used for future embryo transfers/pregnancies. It also helps with fertility preserving as the embryo transfer can be performed at a later time when you are ready for the pregnancy.

Day 3 embryo transfer: This is also known as cleavage embryos. Day 3 embryos are opted for transfer when the number of embryos formed are less or they are not developing well in the lab as the embryos have a better chance of survival in the woman’s womb.

Day 5 embryo transfer: Also known as blastocysts. They have around 60-120 cells within. Day 5 embryos are preferred as they are more genetically healthy and have better success with pregnancy.