Embryo screening PGT

[Pineappletree]

Has anyone done preimplantation generic screening test. I'm 40 years old and my IVF journey started 2 year ago. I have been through two IVF cycles, a total 3 transfers (one fresh & two FETs). The last one was done on 4th Nov and I found a positive result on 14th. However, it turned negative the following Mon so I was offered another two blood tests for HCG. It is very low and the second time it even came down a bit to 22mIU/ml. It seems to indicate a failing pregnancy and I'm worried it might turn out as an ectopic pregnancy as I experience one side cramping pain. It is really sad and hopefully I can find out a bit more with blood test and ultrasound scan next week.

I was told at my age group, the major reason for a failed pregnancy is due to the embryo that might be abnormal. I'd consider to do the screening test (PGT) as you would certainly understand how desperate I am after these many tempts. Has anyone done it? Any experience at all. Many thanks.