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Follicles are not eggs

Posted Apr 26 2010 3:48am

Ovarian follicle Image via Wikipedia

I just finished a consultation with a young woman who had a very low AMH level. I explained to her that this meant she had poor ovarian reserve, and might need to consider using donor eggs.

She was understandably very upset. " How can that be true, doctor ?" she demanded. " My gynecologist has done 4 IUI cycles for me and I had at least two 20 mm follicles in each cycle which would rupture on Day 14. She told me I was young and had good eggs, so how can you now say my egg quality is poor? "

Women know that their chances of getting pregnant depend upon the quantity and quality of their eggs - what is known as their ovarian reserve. They know that if they have regular cycles, this usually means that they are ovulating; and that egg quality declines with age. This is why most young women with ovulatory cycles usually assume that their egg quality must be good. This is a reasonable assumption, and one which most gynecologists also share.

However, it's hard to measure the quality of eggs. Eggs are microscopic structures, which can be evaluated only by doing an IVF treatment cycle , when the embryologist actually gets to see them under his microscope. Follicles, on the other hand, are just black bubbles on the screen which we can track on serial ultrasound scans . Since most follicles contain eggs, traditionally we have measured egg quality indirectly, by using ultrasound scans for follicular monitoring. If the follicles grow well and they rupture, the logical conclusion is that the quality of the eggs within the follicles must be good.

Unfortunately, this is not always true. The follicle is just a black bubble on the ultrasound screen; and some follicles may be empty; while others may contain poor quality eggs. And just because you ovulate every month does not mean that your egg quality is good enough to make a baby !

What about testing the estradiol levels ? This again has the same limitation. The estradiol is not produced by the egg, but by the granulosa cells which line the ovarian follicle. Thus , even if the estradiol levels are good, the egg quality may still be poor. FSH levels used to be the gold standard for assessing egg quality, but this is not very reliable either, for exactly the same reason. Thus, while most women with high FSH levels have poor eggs ( both the quantity and quality are likely to be impaired), many women will also have poor quality eggs, inspite of the fact that their FSH is normal, because the FSH is only an indirect marker of egg quality.

The most reliable test for egg quality is the new blood test which checks AMH levels. This is not foolproof either, but it does provide much more accurate information about ovarian reserve than the older tests. If you are infertile, please ask your doctor to get your AMH level tested - or get this done yourself. This will give you a much better idea of your ovarian function !



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