So if i have "scattered fibroglandular densities" and this is "normal", why do i have to have an ultrasound?

Breast densities: Fibroglandular densities are common and do not imply malignant disease or the potential for same. These entities do cause more difficulty in reading digital mammograms, but without "microcalcification clusters" on mammography, there is no cause for alarm. An ultrasound is usually not going to provide more information.

We need to have more details about your mammogram. Fibroglandular densities by themselves are not cause for concern, but there might have been other findings which required ultrasound. Check to see what BIRADS category your mammogram was. if categoryII or higher, it implies presence of other findings. In addition your doctor may have palpated a lump for which an ultrasound might be needed.