A bilateral screening mammogram is a specialized X-ray examination designed to detect early signs of breast cancer in individuals who are not experiencing symptoms. The term “bilateral” means the procedure images both the right and the left breast. This preventative check uses low-dose X-rays to create detailed images of the internal breast tissue. The screening aims to find small changes, such as masses or microcalcifications, that may indicate developing cancer before they can be felt. Early detection through this method significantly improves the chances for successful treatment.
How the Screening Procedure Works
The bilateral screening mammogram is performed by a specialized technologist using a dedicated mammography unit. The patient stands in front of the machine, and the technologist carefully positions one breast at a time onto a support plate. A parallel plastic paddle then lowers to firmly compress the breast tissue between the two plates.
This compression is a necessary step that spreads the tissue apart, ensuring a clearer image while simultaneously reducing the radiation dose required for the X-ray. Although the compression can cause temporary discomfort or pressure, it typically lasts for only a few seconds per view. For a standard screening, the technologist usually takes two distinct X-ray views of each breast, once from top-to-bottom (craniocaudal) and once from an angled side view (mediolateral oblique), resulting in four total images. The entire process is relatively fast, often taking less than 15 to 20 minutes to complete.
Screening Versus Diagnostic Mammography
The difference between a screening and a diagnostic mammogram lies in the patient’s condition and the exam’s purpose. A screening mammogram is a routine preventive check performed on individuals who have no existing breast complaints, such as a lump, pain, or nipple discharge. Its goal is to look for signs of cancer when it is too small to be detected by physical examination.
A diagnostic mammogram, conversely, is a targeted examination performed when a patient has breast symptoms or when an abnormality is detected on a prior screening mammogram. It serves to investigate a specific area of concern, often requiring the radiologist to be present during the exam to guide the technologist. Diagnostic procedures often involve additional, specialized views beyond the standard four, such as magnification or spot compression views. Being called back for a diagnostic mammogram after a screening does not automatically mean cancer is present.
Practical Steps: Preparation and Follow-Up
Proper preparation helps ensure the best possible image quality for the radiologist to review. Patients must avoid applying deodorants, antiperspirants, powders, lotions, or creams to the chest and underarm area on the day of the exam. These products contain substances that can appear on the X-ray image as white spots, potentially mimicking microcalcifications and leading to an inaccurate reading or the need for repeat imaging.
Wearing a two-piece outfit is recommended, as this allows the patient to easily remove only their top clothing during the procedure. Patients should inform the technologist if they have breast implants or if they have had prior mammograms at a different facility. Bringing records for previous exams is important because comparing new images to older ones helps the radiologist identify subtle changes over time.
Following the procedure, the images are sent to a radiologist, who interprets the findings and assigns a result using a standardized system. This system is called the Breast Imaging Reporting and Data System (BI-RADS), which categorizes the findings with a numerical score from 0 to 6. For example, a BI-RADS 1 means the result is negative, while a BI-RADS 0 indicates an incomplete finding that requires additional imaging, such as a diagnostic mammogram or ultrasound. The results are typically communicated to the patient and their healthcare provider within a few days to two weeks, depending on the facility.