17.1 Screening vs Diagnostic Mammography

Why the screening-versus-diagnostic split is an ARRT item

ARRT's Mammography content specifications (Board approved July 2024; implementation date September 1, 2025) place screening and diagnostic mammography together under Procedures 2.C, Imaging Examinations. The question is not whether you can spell the words. It is whether you put the right patient on the right schedule, acquire the right views, involve the interpreting physician at the right time, and close communication under the Mammography Quality Standards Act (MQSA).

A screening room that "just adds a spot view" for a lump is no longer a screening exam. A diagnostic patient who is sent home without a final assessment because nobody was available to protocol ultrasound has not finished diagnostic work. Those are pathway errors, and they are fair game on a postprimary exam.

Screening mammography: asymptomatic by design

Screening mammography is a routine examination of a patient who has no current breast symptom that needs problem-solving today. The usual presentation is an interval study ordered because the patient meets a screening indication (age, risk, or referring-clinician judgment), not because a new lump, discharge, or skin change is being worked up.

The standard screening acquisition is four views: craniocaudal (CC) and mediolateral oblique (MLO) of each breast. Many facilities add digital breast tomosynthesis (DBT/3D) to that set, with or without a synthesized 2D image. DBT changes what the radiologist can scroll through. It does not change the pathway: an asymptomatic patient is still a screening patient. Tomosynthesis on a screening unit is still screening; tomosynthesis used to work up a recalled mass is diagnostic.

Two reading models appear in practice:

• Batch reading: screening studies are interpreted later in a dedicated session. The patient leaves after images are obtained. This matches the FDA patient-facing description of screening as images that a qualified physician typically reviews later.
• Online reading: a radiologist interprets while the patient is still in the department. Some screening programs use this to cut callbacks. Diagnostic programs use it because extra views and ultrasound often happen the same visit.

Neither model lets you skip MQSA communication. Facilities must provide a written mammography report to the referring healthcare provider as soon as possible, but no later than 30 days from the examination (21 CFR 900.12(c)(3)(i)). Each patient must also receive a lay-language summary of results within 30 calendar days — handed over, mailed, or sent electronically such as through a portal (21 CFR 900.12(c)(2)). When the final assessment is Suspicious or Highly suggestive of malignancy, FDA requires the facility to communicate the lay summary and recommended next step to the patient within 7 calendar days of the final interpretation. As of September 10, 2024, breast density notification belongs on both the medical report and the patient lay summary for screening and diagnostic mammograms. MQSA does not treat diagnostic exams as exempt from density language.

Screening interpretation is usually limited to Breast Imaging Reporting and Data System (BI-RADS) categories 1 (negative), 2 (benign), or 0 (incomplete — need additional imaging). A screening BI-RADS 0 is a callback (recall). It is not a six-month "probably benign" plan and it is not next year's screening. ACR BI-RADS medical-audit benchmarks typically place screening recall in a roughly 5–12% range; most screening patients go home as 1 or 2.

Self-referred patients still get a lay summary. MQSA also requires a system to refer patients who have no provider when the assessment is probably benign, suspicious, or highly suggestive of malignancy.

Diagnostic mammography: something to solve today

Diagnostic mammography is individualized imaging for a current problem. ARRT lists it beside screening because you must recognize the indications that take a patient off the four-view screening conveyor.

Typical diagnostic entries:

• A symptom: palpable lump, focal pain, nipple discharge, skin thickening, erythema, dimpling, or nipple/areolar change
• A callback from screening (BI-RADS 0)
• Short-interval follow-up after a prior diagnostic BI-RADS 3 (probably benign)
• Other problem-solving: a finding first seen on another modality, a post-surgical question, or an implant-related concern that needs tailored views

Diagnostic work is radiologist-directed. You may start with comparison to priors and a targeted set, then add spot compression, magnification (especially for calcifications), 90-degree mediolateral (ML) or lateromedial (LM) views for triangulation, and rolled, exaggerated, cleavage, or tangential views as the finding requires. Breast ultrasound is often performed the same day for a mass, asymmetry, or palpable area. The patient commonly waits so a final BI-RADS category (1 through 6, or still 0 if another test is needed) can be issued before she leaves.

Do not keep a palpable mass on a screening slot. If a patient arrives labeled "screening" and reports a new lump, skin change, or other focal symptom, that visit is diagnostic work. Convert the order, mark the finding, and get radiologist involvement. Parking a palpable abnormality inside a batch-read screening study delays care and collides with both MQSA's screening-versus-diagnostic distinction and BI-RADS logic.

Recall from screening versus diagnostic from the start

These two diagnostic patients both end up in the diagnostic room. They are not identical on the schedule, and exam items love the difference.

A recall patient already has a screening finding that was incomplete. She received (or will receive) a BI-RADS 0 communication and returns for additional mammographic views, often with ultrasound. A diagnostic-from-the-start patient never should have been labeled screening. The 45-year-old with a new mass is not "screening plus a spot." The 55-year-old with a BI-RADS 0 letter is not due for "next year's screening."

After a complete diagnostic look, BI-RADS 3 is the category that creates short-interval follow-up. Assigning BI-RADS 3 from an incomplete screening study, without diagnostic workup, is the classic error. Screening incomplete = 0. Diagnostic probably benign after a full evaluation = 3, then a diagnostic short-interval visit — not a screening appointment.

Asymptomatic patients with implants stay on the screening pathway, but they need implant-included and implant-displaced (Eklund) views. They become diagnostic only if a finding or a clinical problem appears.

Exam traps

• The requisition can lie. Recheck the reason for exam at check-in. "Screening" on paper does not override a lump the patient shows you in the dressing room.
• DBT is a tool, not a pathway. The clinical indication decides screening versus diagnostic.
• Male patients with focal breast symptoms are diagnostic, not population screening.
• Density language is not a screening-only extra after the 2024 MQSA amendments.
• "Diagnostic" does not mean cancer. It means problem-solving imaging. Most diagnostic patients still leave with a benign or probably benign assessment.

When you can say, in one sentence, whether today's patient is asymptomatic four-view screening, a callback from BI-RADS 0, or diagnostic from the start — and you know who waits in the department — you are answering Procedures 2.C the way ARRT wrote it.