Reasons you may not be able to have the test or why the results may not be helpful include:

• Deodorant, perfume, powders, or ointments applied to the breasts or under the arms before the test. They may interfere with the X-ray pictures.
• Breast implants or scar tissue from previous breast surgery. This may make a mammogram harder to interpret.

A mammogram is not usually done if you are:

• Pregnant, because the radiation could damage your developing baby (fetus). If a mammogram is absolutely needed for diagnosing a problem, a lead apron will be placed over your abdomen to shield your baby from exposure to the X-rays.
• Breast-feeding, because breasts that contain milk are very difficult to examine.