I had both the same day, and the mammogram come back normal, but the ultrasound came back abnormal? which one is more accurate?

Apples & Oranges: Neither test is "better"--the result of the test must be interpreted within the clinical context it was ordered. The radiologist who interprets these studies will take all of this into account when coming up with one recommendation. This will be codified as a birads category, which your doctor will use to decide whether to observe or biopsy what was seen.

Different: Mammogram and ultrasound look at different qualities. Mammogram is good at seeing tissue that is more dense than surrounding tissue and for calcifications. Ultrasound is good at seeing the whether those tissues are solid or fluid-filled or both. The two together, in addition to the physician's exam, help to create a more complete picture. Trust in your doctor to interpret these findings for you.

Follow through: I agree with my colleagues answers. It is important that you follow through with the recommendations. If a biopsy is needed, make sure you get a core needle biopsy. The good news is that 80% of biopsies performed with have benign, noncancerous results. If a 3 or 6 month repeat film is needed, be sure you go back and get it completed. Good luck!

They are: complementary tests using different technologies and imaging different tissue characteristics. It is not uncommon for an abnormality to be see on one and not the other. Not seeing it on one does not negate the finding on the other. If it is suspicious, it likely needs biopsy.