Good luck to you with the biopsy. If you have a low tolerance to pain, take PERSCRIPTION strength Motrin before the procedure. It will be over in a flash, and that's all I'm going to say about it.
The reason they do this is to see where your levels are - to see if your cycle is in sync with your ovulation. The technical word for this is the Lunar phase of your cycle. Mine was off, so then I got the label of having a lunar defect (hope I'm spelling lunar right for this). Lunar may be something like Lunear?? Sorry if I'm mis-spelling this. They sometimes want to do more than one biopsy to make sure the levels are accurate.
I wish you all the luck in the world... and remember, it only lasts for a few seconds (20-30).
Great question!
{{{{ HUGS
}}}