Why do doctors ask for both mammogram and ultra sound for the breast?

Mammo and U/S: A few studies have shown that mammography coupled with ultrasound can increase the chance of finding smaller breast cancers; however other studies have shown that it does not help with specific diagnoses and can lead to false positive results. The jury is out a bit on this one but some centers prefer to have both lines of diagnostic imaging to increase chance of catching a cancer.

Different things: Mammograms show distortions in the breast architecture. Ultrasounds are very good for differentiating whether a mass is cystic or solid. So the 2 tests give you different information.

Depends: The mammogram and ultrasound can see different things. A mammogram may see a density or nodularity. An ultrasound can see if there are small solid or fluid (cyst) nodues in the breast. Often these Two tests can be complimentary in their findings.

They are not: routinely ordered together. They are complementary tests, and the combination of ultrasound and mammographic findings in the setting of a Breast abnormality often provides more useful diagnostic information than either test alone. In the screening setting, there is some evidence that ultrasound plus mammography in women with dense breasts may have some benefit.