Confirming pregnancy after IVF and Egg Donation . The first ultrasound in which we can see the pregnancy is a very emotional time for the parents, especially for patients who have gone through treatments for assisted reproduction. For these patients, after having a positive pregnancy test , their anxiety does not go away but gets stronger until the pregnancy is seen to develop normally. Therefore it is very important to know what happens during this exploration, and what to expect.
When is it done?
It should be carried out between week 5 and 7 of pregnancy, therefore between 3 and 5 weeks after embryo transfer. To calculate the pregnancy after IVF, we always set a theoretical last mentrual period date 14 days before egg retrieval.
Exactly one month after the embryo transfer is a great time to carry out the scan and see clearly if the pregnancy is progressing or not. If this is done sooner, we can create confusion and uncertainty since most of the time it will not be conclusive.
How is it done?
The ultrasound must be done vaginally. This shows the images more clearly, and it is more precise in showing that everything is evolving correctly. We know that carrying out the ultrasound this way does not negatively affect the pregnancy.
Why is it important to do an ultrasound in the 6th or 7th week?
- We can confirm that the pregnancy is in the uterus, and rule out ectopic pregnancy (found outside the uterus).
- We can see if it is a single or a multiple pregnancy.
- It allows us to evaluate whether or not the pregnancy evolution is as it should be. If it is not evolving well, it can give us an idea as to why.
What will we see in the scan?
In the first scan after IVF carried out in week 6 or 7 of pregnancy we can see the following structures:
- Gestational Sac. This is the earliest structure seen. It is a dark image, surrounded by a halo, found within the uterus (in the endometrium, which we observed growing during the ovarian stimulation). The average size at week 6 is around 14mm, but this varies greatly can sacs that are much smaller and much bigger are not considered abnormal.
- Yolk Sac. This is a vestigial structure that is seen at the start of embryonic development. Its round, white shape, resembling the follicles during stimulation. It measures around 3-4mm, and if it is larger than 6mm it is considered a poor prognosis.
- Heart beat. Tends to appear around week 6. The heart rate at this time is between 90 and 110 beats per minute, and will increase in the coming weeks.
- Embryo. The cell mass that has all of the embryos organs. It is a structure attached to the yolk sac. In week 6 sometimes it is not seen yet, as its size is between 2-8mm. this varies greatly, and will grow very quickly (around 1mm daily).
In case these structures are not seen, or their sizes are not as expected, does this mean the pregnancy is lost?
We msut be cautious in interpreting the ultrasound findings at this time, since there are a number of factors that can lead to an incorrect diagnosis:
- The variations in normal embryo development. Even though it is very early on in the pregnancy, there are many variation in the appearance of ultrasound findings. Therefore any diagnosis must be confirmed a few days later.
- Differences in the quality of the image depending on the patient. Every patient is different, and their tissues pass the ultrasounds waves in different ways. Images can be unclear if the transmission is not good.
- Placement of uterus and location of gestational sac. Depending on the distance between the ultrasound probe and the gestational sac, the image can be more or less clear. This can mean that the diagnosis is inconclusive.
Dr. Joaquín Llácer, Co-Medical Director of Assisted rReproduction at Instituto Bernabeu.
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