After having FSH injections for a week or so you have a vaginal ultrasound scan to check on your response to the drug. The ultrasonographer counts the number of follicles and measures their sizes (I talk more about this examination in Chapter 5). You may also have blood tests to determine your estradiol levels, which is another gauge of your response to ovarian stimulation.
Ideally, the stimulation results in the simultaneous growth of between ten and 15 follicles that reach a size of 18 mm or more in diameter before the final maturation of the eggs is triggered with an hCG injection.
After follicles start growing, they grow by about 2 mm every day. If the scan shows that you have a good number of follicles but they haven't yet reached their optimum size, you're advised to take FSH for another few days before having the hCG trigger injection. Figure 6-2 shows an ultrasound image of an ovary with multiple large follicles (the black holes): An ideal response to IVF stimulation.
An ideal response to FSH.
An ideal response to FSH.
iBEn The number of follicles you have isn't always an indication of how many eggs you'll get. If you have a couple of large follicles and lots of tiny ones, probably only the larger follicles will produce mature eggs. Even if eggs are found in some of the small follicles, these eggs are unlikely to be mature and able to fertilise.
Sometimes the result of the stimulation is disappointing. When only one or two large follicles are seen, your doctor may suggest that you stop the treatment and try again with a higher dose. If you're already taking the highest dose, your doctor will probably suggest that you keep going and cross your fingers that one of the eggs is a winner. Figure 6-3 shows an ultrasound image of an ovary where there are only two decent-looking follicles: A disappointing stimulation result.
When the scan shows that you have some small follicles but no large ones, your doctor may increase the dose of FSH and ask you to have another scan a few days later. If the follicles respond to the higher dose, you'll have an hCG injection when they reach the desired size ready for egg collection two days later.
A disappointing response to FSH.
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A very small number of women develop a total over-the-top response to FSH and their ovaries become much enlarged because they're full of growing follicles. In Figure 6-4 you can see what that looks like on ultrasound: Masses of follicles of all sizes crowding the entire ovary. This response is known as ovarian hyperstimulation syndrome and it's every IVF doctor's fear because of the potential danger for the woman. However, managed well the risk can be minimised, and in Chapter 10 I explain what your doctor does to limit your risks.
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A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.