Have you had any treatment?
If VA is suspected clinically (and it is highly likely in the setting of low systemic estrogen), then this doesn't usually require any investigation, it requires estrogen.
I don't even know what "investigation" for VA would look like - certainly anything invasive would be clinically inappropriate and a biopsy would only be considered if there was suspicion of a more serious condition, not for something that affects virtually all untreated or suboptimally treated menopausal women.
Topical estrogen cream and or pessaries can be used, however in the absence of contraindications systemic estrogen should be considered as the benefits of this extend way beyond the genitalia.
