My mammogram report results came back birads 4 but my sonogram report came back negative so why does my doctor recommend a breast biopsy?

Because ...: If a suspicious lesion is noted on mammography an us is obtained. This allows for better definition of the lesion in the breast. However, a "negative" us does not rule out an underlying problem and the correct next step is to proceed with your physicians recommendation, in this case a biopsy. None of the imaging techniques are perfect, the final decision is based on all the information.

Better safe: Different types of breast imaging can be better or worse at finding certain abnormalities. A biorads 4 suggests that the radiologist cannot completely exclude cancer; however, benign lesions can also have this score. Consider a second opinion if you are not confident that a biopsy is necessary.

Get it done!: A birads-4 mammogram describes a finding consistent with possible cancer in the breast. The lesion may be a suspicious cluster of microcalcifications which would not be necessarily seen as a mass on ultrasound. It is important to have the area biopsied.

Mammo and : ultrasound are complementary tests. Some abnormalities may be seen on one, but not the other. So a suspicious mammo finding that cannot be seen on ultrasound is still a suspicious mammo finding, and likely needs biopsy.