Saturday, April 14, 2012

Australian Undergoing Natural Cycle FET: Timing Is Everything!!!


Hi Dr Ramirez, I am 32 from Australia. I am about to embark on my first Frozen Embryo Transfer, using my natural cycle. I have one child (5yrs old) who was conceived spontaneosly after removing my endometriosis 3 months earlier. My doctor will be conducting ultrasounds and blood tests to determine ovulation and progesterone levels. This starts on day 12. My embryos (which were all top rating) were frozen on day 2.

What is the latest time (post ovulation) they could transfer these soon to be 3 day old embryos? I'm just worried because 3-4 days post ovulation would most likely be on a Saturday or Sunday and the lab is not open on a Sunday. Is delaying it or doing it too early acceptable?

Thank you for your time. Kind Regards, Z. from Australia


Hello Z. from Australia,

First let me say that I am very surprised that your doctor has chosen to do this with a natural cycle. Implantation is very time sensitive, meaning the timing of the transfer has to be pretty exact. If the development of the lining is out of sync with the embryo stage, then implantation will not occur. The timing of the endometrial lining development is very dependent on progesterone stimulation and that cannot be measured by blood tests because the blood levels do not reflect the endometrial levels or the endometrial architecture.

In terms of your question, I cannot believe that an IVF center would not be open on a Sunday if they have to be because of timing. Again, I know I'm being redundant, timing is EVERYTHING in a frozen embryo transfer. The embryos can be transferred at any cell stage, as long as it coordinates with the stage of endometrial development. In a normal cycle, the embryos are transferred one more day than the number of days you have been on progesterone. For example, for a Day 3 embryo, it is transferred on the 4th day of progesterone. For a Day 5 embryo, it is transferred on the 6th day of progesterone. What I would suggest for you, if the 3rd day falls on a Sunday and the clinic cannot do a transfer on that day, culture out the embryos until Day #5 and transfer at that time. They will have developed into blastocysts by then which might help your chances for implantation since the embryos will be closer to the stage they need to be in for implantation.

Good Luck,

Dr. Edward J. Ramirez, M.D., FACOG
Executive Medical Director
The Fertility and Gynecology Center
Monterey Bay IVF Program
Monterey, California, U.S.A.

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