@Bluemeadowbaby the EMMA and ALICE is done at the same time as an ERA. You have a mock medicated FET and on the day they would do a transfer they take a sample of the endometrium using suction. That sample goes off the a company that does all the tests. It is useful in people that have had several unsuccessful cycles and I'd also recommend it for women with a DOR who have limited embryos.
The ERA says whether the endometrium is receptive, 1 in 3 women have a transfer window out of sync with the protocol usually used, I was one of those, so I got told to be on progesterone for 145 hours rather than the standard 120.
The ALICE looks for bacteria that cause chronic endometritis.
The EMMA looks at the percentages of bacteria, good bacteria (lactobacillus) and various types of dysbiotic bacteria.
This study https://doi.org/10.1016/j.ajog.2016.09.075 separated women with more than 90% lactobacillus vs those with less than 90% lactobacillus, the outcomes were statistically significant:
Implantation 60.7% vs 23.1%
Pregnancy 70.6% vs 33.3%
Ongoing pregnancy 58.8% vs 13.3%
Live birth 58.8% vs 6.7%
In my case I had 0.00% lactobacillus so I'm hoping this explains why I've never had a BFP. I have had thin lining in my natural cycles, light periods, my specialist said there was no lining there when she was taking my sample and said it looked strange on the screen on the day of the biopsy and also in my FET. I'm hoping this microflora explains the lining issues, but I just don't know.