OB-GYN 101

Mammography is very good at detecting radio-opaque changes, such as calcifications or architectural distortion from a mass effect.

Ultrasound, in contrast, is very good at distinguishing cystic from solid masses. This is probably most useful following mammographic findings of a benign-appearing, non-palpable density, although it can also be used with palpable masses.

Read more about this in the
Guide to Clinical Preventive Services
U.S. Department of Health and Human Services