Eggs are not follicles

IVF patients often don’t understand the difference between follicles ( which are affectionately called “follies” ) and eggs .  Doctors are sometimes responsible for this confusion , because we usually loosely refer to the follicles we see on your ultrasound scan as eggs. This is especially true during IUI cycles; or when the scans are being done by a sonographer or technician. When she sees that your ovaries have responded well to the superovulation, she will often say – Good, your eggs are growing well. In reality, eggs are microscopic structures which cannot be seen on ultrasound scans. They are only 100 microns ( 0.1 mm)  in size, and can only be seen by the embryologist in the IVF lab when he scans the follicular fluid the doctor sends him during the egg retrieval under the stereozoom microscope . Ultrasound scans allow us to track the growth of the follicles in your ovaries.  Follicles are seen as tiny black bubbles on the scan, because they contain follicular fluid. They range in size from 4 mm – 25 mm; and the eggs grow within these follicles. However, not all follicles  contain eggs , which is why the correlation between the number of follicles seen on the IVF ultrasound scans and the number of eggs which are actually retrieved is not perfect. When all the follicles grow at the same rate ( a synchronous cohort), then timing the HCG is much easier. However, often the growth is asynchronous; and some follicles may become  big...
Source: The Patient's Doctor - Category: Obstetricians and Gynecologists Source Type: blogs