Mammography — How It Works, Benefits & Recovery — Procedure Guide, Recovery & Risks | MyMedicPlus

Mammography is a specialised low-dose X-ray imaging technique designed to visualise the internal structures of the breast — adipose tissue, fibroglandular parenchyma, ducts, and any abnormal masses or calcifications — to detect breast cancer at an early, treatable stage. During the examination, each breast is compressed between two plastic plates (the compression paddle and X-ray receptor) to spread the tissue evenly, reduce motion blur, improve image quality, and minimise the radiation dose required. Each standard mammogram involves two views of each breast: the craniocaudal (CC) view from above and the mediolateral oblique (MLO) view at an angle to include the axillary tail of the breast. Digital mammography (full-field digital mammography, FFDM) has replaced film mammography at most accredited centres globally. Three-dimensional mammography or digital breast tomosynthesis (DBT, commonly called 3D mammography) acquires multiple low-dose images from a rotating X-ray tube and reconstructs thin slices through the breast — increasing detection of invasive cancers by approximately twenty to forty percent while reducing false-positive call-backs by up to fifteen percent compared to 2D FFDM. Mammography is classified as either screening mammography — performed in asymptomatic women within a defined age group — or diagnostic mammography — performed to evaluate a specific clinical concern (palpable lump, nipple discharge, skin change) or to further characterise an abnormality found on screening. The radiation dose per standard two-view mammogram is approximately three to four milligray (mGy) per breast.

Screening mammography recommendations vary by country and guideline-issuing body. In the United Kingdom, the NHS Breast Screening Programme invites women aged fifty to seventy-one every three years. The American Cancer Society recommends annual mammography from age forty-five (or forty for those who choose to start earlier), switching to biennial at fifty-five. The US Preventive Services Task Force (USPSTF) 2024 updated recommendation advises biennial mammography from age forty. Women at high lifetime risk of breast cancer (twenty to thirty percent or above, calculated by Tyrer-Cuzick, BOADICEA, or similar risk models) or BRCA1/BRCA2 gene carriers are recommended annual mammography plus annual MRI from age thirty (UK, NICE NG12) or twenty-five to thirty (USA, ACS). Diagnostic mammography is indicated for investigation of a symptomatic breast — palpable lump or asymmetry, skin or nipple changes, nipple discharge, axillary lymphadenopathy — at any age, though in women under thirty-five ultrasound is typically the first-line imaging modality due to dense breast tissue limiting mammogram sensitivity. Mammography is appropriate regardless of gender — males with gynaecomastia or palpable breast abnormality may require targeted assessment; male breast cancer, though rare (less than one percent of all breast cancers), is imaged by mammography when clinically indicated.

The patient is requested not to apply deodorant, perfume, or powder to the axillae or breast area on the day of examination, as these may appear as calcifications on the image. A radiographer positions each breast in turn on the X-ray detector plate. For the craniocaudal (CC) view, the patient faces the mammography unit, the breast is lifted and placed horizontally on the detector, and gentle compression is applied with the paddle until adequate breast tissue spread is achieved. The patient holds still for the two-second X-ray exposure. For the mediolateral oblique (MLO) view, the patient is rotated approximately forty to sixty degrees and the pectoral muscle is included at the image edge. Compression is firm and may cause mild discomfort, particularly in the days preceding menstruation when breast tissue is more tender; scheduling for the week after menstruation is recommended when possible. Total examination time is fifteen to thirty minutes. Results are reported by a radiologist using the ACR BI-RADS (Breast Imaging Reporting and Data System) lexicon: BI-RADS 0 (recall for additional assessment), 1 (negative), 2 (benign), 3 (probably benign, six-month follow-up), 4 (suspicious, biopsy), and 5 (highly suggestive of malignancy, biopsy). For DBT (3D mammography), an additional three to five seconds per view reconstructs the tomographic slices reviewed slice by slice.

Population-based breast cancer screening with mammography has consistently demonstrated a twenty to thirty percent reduction in breast cancer mortality in randomised controlled trials (Swedish Two-County Trial, HIP Trial, and subsequent meta-analyses), with observational data from mature national screening programmes confirming sustained mortality benefit. Early-stage diagnosis enabled by screening facilitates breast-conserving surgery (lumpectomy) rather than mastectomy in a higher proportion of patients, and reduces the need for chemotherapy by enabling treatment of smaller node-negative tumours. The sensitivity of mammography for breast cancer is approximately seventy to eighty-five percent overall, falling to sixty to seventy percent in women with dense breast tissue (category C or D on the ACR density scale) where dense fibroglandular tissue may mask tumours. 3D tomosynthesis improves cancer detection rates by twenty to forty percent in dense breasts and is now the preferred modality at many accredited breast imaging centres. Supplemental screening with ultrasound or MRI detects additional cancers in dense-breast women beyond mammography alone, increasing detection rates by three to four additional cancers per one thousand women screened.

Mammography's primary risks are false positives, false negatives, and radiation exposure. False positive results — findings on mammography that prove benign on further assessment or biopsy — occur in five to ten percent of screening mammograms, leading to recall for additional imaging and potentially biopsy in approximately one to two percent. Over ten years of annual screening, approximately fifty to sixty percent of women will experience at least one recall, and ten to twenty percent will be recommended biopsy. The psychological impact of false positives — anxiety during the investigation period — is well-documented, though most women report willingness to accept this for the benefit of early detection. False negatives — missed cancers — occur in approximately ten to twenty percent of mammograms; interval cancers presenting between screening rounds are more commonly biologically aggressive. Dense breast tissue is the primary cause of missed cancers in mammography. Radiation exposure from screening mammography is very low — approximately three to four milligray per session. The estimated absolute lifetime attributable cancer risk from ten years of biennial screening mammography starting at fifty is approximately one case per one hundred thousand women — negligible compared to the benefit of preventing breast cancer deaths from screening. Overdiagnosis — detection of cancers that would never have caused symptoms or death in the patient's lifetime — is a genuine but debated limitation, estimated at fifteen to thirty percent of screen-detected cancers in some analyses.

No recovery is required after mammography. Mild breast tenderness from compression resolves within minutes to hours. Results in screening mammography programmes are typically reported within two to four weeks by post or online portal; urgent results are communicated more promptly. In the UK NHS Breast Screening Programme, women recalled for further assessment are seen at a one-stop assessment clinic within two weeks of recall notification, where additional mammographic views, digital breast tomosynthesis, ultrasound, and ultrasound-guided or stereotactic biopsy can be performed in one appointment. In diagnostic mammography for symptomatic patients, results are typically reported to the referring clinician within two to five working days. BI-RADS 3 (probably benign) findings are followed up with repeat mammography at six months; BI-RADS 4 and 5 are referred for biopsy. Following a normal or benign mammogram in the screening context, women continue with routine screening at the recommended interval. All women are advised to maintain breast awareness — reporting any new lump, skin change, nipple inversion or discharge, or axillary lump promptly to their doctor regardless of when their last mammogram was performed.