If there is a question of an abnormality on your screening mammogram, this may require additional imaging to fully evaluate the findings. Nationwide, approximately 1 in 10 women who have a screening mammogram will need additional mammogram views, and possibly breast ultrasound. Often, the possible abnormality can be from superimposed or overlapping normal glandular tissue caused by a non-uniform pattern in the normal breast tissue. The questioned abnormality often resolves when the breast is positioned in a slightly different way. If any area remains abnormal on additional mammography work-up, a breast ultrasound may be necessary as another means of evaluation. Ultimately, any suspicious or new finding may need either short-term follow up imaging to verify its stability, or occasionally a biopsy to find out the type of tissue present. Again, most of these findings are due to benign causes, but only a thorough work-up can exclude a serious lesion.
Although mammography is still the most sensitive test for identifying early breast cancer, it does not identify all breast cancers. As many as 10 to 15 percent of breast cancers cannot be seen with mammograms. All cancers affect the normal breast tissues, however some of these changes do not show up on mammograms. This problem is somewhat greater in younger women when the breast contains more fibrous and glandular tissue. However, mammography is still very useful.
Therefore, breast self-examination is important. A lump, particularly a new lump or fullness, can be significant even if both your mammogram and breast ultrasound have not revealed an explanation. In this case, surgical evaluation may still be necessary to determine the reason for the new lump.