- By: Jananam
- March 17, 2025
Frozen Embryo Transfer Steps
Frozen embryo transfer steps begin with preparing the uterine lining, most often by the hormone replacement method. You attend on day 2 of your period for a scan confirming a thin lining and no ovarian cysts, then start estrogen tablets every eight hours. A repeat scan about ten days later checks lining thickness before transfer.
Embryo transfer is an important step in the IVF process. There are two methods which we use to prepare the lining (endometrium) for embryo transfer. We commonly use the hormone replacement method. The other is letrozole – ovulation method.
Hormone Replacement Method Steps:
1. Here, we advise you to see us on day 2 of your period.
2. If your day 2 falls on a Sunday, we will see you on day 3
3. You will have a scan to ensure that the uterine lining is thin and that there are abnormal cysts in the ovaries
4. You will be advised to start estrogen tablets two to three times a day (every 8 hourly)
5. This prevents natural ovulation from occurring in that month.
6. We will review you for a scan 10 days later to see if the endometrium is thick (usually more than 8 mm)
7. We will then advise you to have a progesterone blood test to ensure that your progesterone test is normal.(<1ng/ml)
8. Occasionally, women may ovulate despite measures taken in which case they have a raised progesterone level and may need cancellation of the cycle.
9. We then start progesterone (injections or vaginal gel)
10. If you have day 3 embryos, transfer will be done on the 4th day of progesterone and if you have a blastocyst, transfer will be done on the 6th day of progesterone.
Letrozole – Ovulation Induction Steps:
1. On day 2 of your period (day 3 if it falls on a Sunday), you will have a transvaginal scan
2. This is to rule out the presence of any cysts in the ovaries and to ensure that the uterine lining is thin
3. We will start letrozole tablet – usually 5mg / day for 5-7 days and then scan you
4. The aim is to encourage the growth of one follicle and thicken the endometrium simultaneously
5. Once we are satisfied with the follicle growth and endometrial thickness, we will advise you to check your progesterone levels
6. If the progesterone level must be less than 1ng, we will trigger ovulation with an HCG injection
7. We will confirm ovulation after 36+ hours and then start progesterone support
8. Once again, a day 3 embryo will be transferred on post ovulatory day 4 and a day 5 embryo will be transferred on post ovulatory day 6.
Embryo Transfer Steps:
1. On the day of the transfer, you will be asked to come in the morning
2. Most transfers are done without anesthesia, but the consultant may on occasion advise you to have anesthesia
3. You will be requested to fill your bladder before the procedure
4. This helps to straighten the uterus, making transfer easier
5. A full bladder also helps us to scan your uterus
6. The transfer procedure involves placing the embryo/embryos within the uterus under ultrasound guidance (simultaneous scan)
7. The embryos are microscopic and not visible to the naked eye. Therefore, we place air bubbles (which are seen as bright spots) on either side of the embryos to ensure correct placement
8. After the transfer, we advise you to lie down for 15 to 20 minutes before you empty your bladder
9. You can walk, climb stairs, and carry out your activities as normal. Movement does not reduce your chance of getting pregnant
10. 80% of a pregnancy is due to the potential of the embryo and 20% is due to the endometrial receptivity.
11. The pregnancy blood test will be done here at Jananam on day 14 after a day 3 embryo transfer and on day 12 after a blastocyst transfer.
12. You will be informed about your results around 4 pm on the pregnancy test day.
What are the steps in a frozen embryo transfer?
How is the uterine lining prepared for a frozen embryo transfer?
Two methods are used. The hormone replacement method is the more common: estrogen tablets from day 2 of the period prevent natural ovulation and thicken the lining. The alternative is a letrozole and ovulation method, which works with your own cycle.
How thick does the endometrium need to be?
A scan about ten days after starting estrogen checks thickness, and generally more than 8 mm is looked for before proceeding. Thickness is not the only factor, as pattern and blood flow matter too, but it is the main measure used at this stage.
Why is a progesterone blood test done before transfer?
To confirm progesterone is still low, usually under 1 ng/ml. Occasionally a woman ovulates despite the medication, which raises progesterone and can mean the cycle is cancelled rather than transferring an embryo at the wrong point in the cycle.
When is the embryo actually transferred?
After progesterone is started, given by injection or vaginal gel. The exact timing depends on the stage at which the embryo was frozen, since day 3 embryos and blastocysts are transferred after different numbers of days of progesterone.
Is a frozen transfer as good as a fresh one?
Frozen transfer is standard practice and lets the lining be prepared without the hormonal effects of a stimulation cycle. It also allows surplus embryos from one egg collection to be used later, which is why cumulative outcomes are the more meaningful measure.
Related reading
- embryo freezing and frozen embryo transfer
- ovarian stimulation for IVF and IUI
- IVF treatment at Jananam Fertility Centre
Clinical references
Independent clinical guidance relevant to this topic:
- HFEA — In vitro fertilisation (IVF)
- ASRM — Practice Committee documents
- ESHRE — Guidelines and legal documents
Watch: Egg retrieval to Embryo transfer..! Complete Post Egg Collection Process in IVF…!
Dr. Vani Sundarapandian explains this on the Jananam Fertility Centre channel.
