In medicine, screening refers to the testing of a person who doesn’t show any signs or symptoms in order to detect a disease in its early stages before it starts manifesting. Thus screening mammography is the type of mammography used in women who do not suffer from any signs or symptoms of breast disease, such as breast pain, a lump or swelling in the breast, nipple discharge, or any other physical deformity. This allows early detection and thus early treatment, which is associated with a better prognosis.
Mammography has contributed to a 36% decrease in breast cancer mortality rate from 1989 to 2012, and a lowered risk of death is not the only advantage of the early detection of a breast lesion. The same breast lump that would have needed a minimally invasive surgery to remove if it had been discovered early may need a much more disfiguring operation if discovered late when it has increased in size and encroached upon other thoracic structures. For example, a breast mass may be too small to feel during a clinical examination but may show up on a screening mammogram. When women above 40 years of age get annual mammograms, the type they’re getting is the screening mammogram.
It should be mentioned that women who had underwent breast reconstruction surgery and have lost all underlying breast tissue need no screening mammograms. Clinical examination of these reconstructed breast is the preferred method of screening. Regarding pregnant women: The risk of radiation exposure to the foetus actually outweighs the benefits of getting screening mammograms regularly, which is why pregnant women only get diagnostic mammograms.