Interesting analogy: "a facial for the uterus." Never heard that one before! But I have heard "tilling the soil."
I had hysteroscopy twice in the office and once in the OR with anesthesia. It is not a difficult procedure.
It might be worth doing to get things ready for good implantation (I do think she's probably right about that), but if you want to go less invasive, you could opt for another saline sonogram.