I had a uterine biopsy (same thing) before my 3rd FET and that one was successful. I made other changes too, so can't say it was the scratch. If we did another transfer in the future I would get the scratch done again. For me, it was more painful than I expected, but well worth it. Insurance covered the biopsy since they also send the lining out to the lab to be checked. Ask your clinic how they code it, and maybe it will be covered.