Dense Breasts and Coding Mammography

Dense Breasts and Coding Mammography

Tune in to this monthly online coding column, facilitated by AHIMA’s coding experts, to learn about challenging areas and documentation opportunities for ICD-10-CM/PCS.

By Paula Mauro and Donna Rugg, RHIT, CDIP, CCS-P, CICA, CCS


At the end of 2018, the New York Times reported the death of Nancy M. Cappello, PhD, an activist for women receiving better diagnostics for breast cancer—the disease she died from on November 15 at age 66.

Cappello’s breast cancer diagnosis was a shock, as it often is. But in her case, the shock was that she had had 11 mammograms in her life, including one six weeks before her cancer was found, and they had all come back clear. A few weeks after the eleventh mammogram, in January 2004, her doctor felt a lump in her breast during a routine physical. A repeat mammogram turned up nothing suspicious. But an ultrasound her doctor had also ordered found advanced stage 3 breast cancer that had spread to 13 lymph nodes.

The cancer hadn’t shown up on a mammogram, Cappello’s doctor said, because Cappello had dense breast tissue; that was the first time she had heard the term.

The National Cancer Institute (NCI) defines dense breast tissue as having more glandular and fibrous connective tissue, lacking the relative amount of fatty tissue that mammography needs to reveal breast tumors. About 40 percent of women who have mammograms have dense breast tissue, which can’t be detected by touch, only through a mammogram.

Mammography Coding Basics

Each mammography encounter needs to be assigned ICD-10-CM diagnosis code(s) and CPT procedure code(s) so the healthcare facility can process it for billing. Let’s discuss some basics for mammography coding as it may have related to Nancy Cappello’s experience.

A diagnosis of “dense breasts” is coded in ICD-10-CM as R92.2, Inconclusive mammogram. It is found in the alphabetic index under main term ‘Dense breasts’: “Only a mammogram can show if a woman has dense breasts. Dense breast tissue cannot be felt in a clinical breast exam or in a breast self-exam.” Per the American Hospital Association’s Coding Clinic First Quarter 2015, page 24, R92.2 is not assigned as a secondary diagnosis when it is discovered during a screening mammogram. Rather, it should be assigned as the primary diagnosis and reason for the subsequent encounter that generally occurs for additional tests (ultrasound, MRI, etc.). Z12.31, Encounter for screening mammogram for malignant neoplasm of breast, is assigned as the primary diagnosis and reason for the screening mammogram encounter. Per the ICD-10-CM classification, R92.2 cannot be assigned with Z12.31 because of an Excludes1 note under Z12.31.

Per section I.C.21.c.5. in the ICD-10-CM Guidelines for Coding and Reporting FY 2019, If additional conditions are documented on the screening mammography by the radiologist (such as calcifications, family history of breast malignancy, etc.), secondary ICD-10-CM codes should be added to the encounter to capture these conditions.

The mammogram CPT procedure codes are generally assigned through the facility chargemaster rather than by a coding professional. The Centers for Medicare and Medicaid Services (CMS) offers guidance for coding mammograms, including:

CMS coverage and frequency limits for screening mammograms:

  • Aged 35 through 39: one baseline
  • Age 40 and older: covered annually
  • Under age 35: no screening mammogram coverage
  • Physician referral/order not required
  • Qualified physician directly associated with facility where mammogram taken must interpret results

The CPT codes used for screening mammography:

  • 77067 – Screening mammography, bilateral (two-view study of each breast), including computer-aided detection (CAD) when performed
  • 77066 – Diagnostic mammography, including CAD when performed; bilateral
  • 77065 – Diagnostic mammography, including CAD when performed; unilateral

A diagnostic mammogram is covered by CMS if one of the following conditions exists:

  • A patient has distinct signs and symptoms for which a mammogram is indicated
  • A patient has a history of breast cancer
  • A patient is asymptomatic but, on the basis of the patient’s history and other factors the physician considers significant, the physician’s judgment is that a mammogram is appropriate
Additional CMS Coding Tips

Z12.31, Encounter for screening mammogram for malignant neoplasm of breast, is the primary diagnosis code assigned for a screening mammogram. If the mammogram is diagnostic, the ICD-10-CM code assigned is the reason the diagnostic mammogram was performed. If a screening and diagnostic mammogram are billed on the same day, modifier GG is assigned to the CPT code to indicate a screening mammogram turned into a diagnostic mammogram. Both tests are submitted on the bill. If a screening mammogram is performed on only one breast (perhaps due to a previous unilateral mastectomy), modifier 52 is added to code 77067 to show reduced services.

It’s critical to understand payer requirements as well as coding guidance (ICD-10-CM and CPT) for mammography to ensure patients receive the coverage their plan allows, and the healthcare organization receives the appropriate reimbursement.

From Patient to Activist

When Cappello learned she had advanced breast cancer, which might have been found earlier if she had known an important fact about her own body, her question was, “Why didn’t I know?” Her doctors estimated her cancer had been growing for several years. If she had known she had dense breasts, Cappello could have requested an ultrasound, 3D mammogram, or an MRI, which would have likely caught the cancer in its early stages.

She learned that telling women they had dense breasts wasn’t protocol, and many doctors didn’t want it to become protocol, fearing it might do more harm than help, frightening women who may not need to be frightened, and needlessly increase testing.

The NCI information cited above indicates that women with dense breasts and their doctors should talk about their personal risk for breast cancer, given their other relative risks. Cappello founded the advocacy group “Are You Dense?” to make it standard for doctors to tell women if they have dense breast tissue and for insurance companies to pay for ultrasound testing for women in this category. Legislation was successfully passed in her home state of Connecticut in 2009 through her efforts, with 36 states following suit on the disclosure issue over the next several years, though insurance doesn’t cover ultrasound for these women in all of those states.

A patient whose breast cancer was detected by an ultrasound ordered after a mammogram revealed she had dense breasts writes in a blog post at, “If Nancy had not worked so hard” at the legislative level, “I am not sure where I would be today.”

Additional References

American Hospital Association (AHA). Coding Clinic for HCPCS, Second Quarter 2002, page 10.

AHA. ICD-10-CM and ICD-10-PCS Coding Handbook. 2019.

CMS. National Coverage Determination for Mammograms (220.4).

American Medical Association. CPT Assistant. December 2016, page 15, 17.

National Government Services. “Screening Mammography.” Preventive Services Guide.

CMS. Diagnostic Mammogram (RAD-005) Billing and Coding Guidelines.


Paula Mauro ( is social media manager and Donna Rugg ( is director, HIM practice excellence, terminology mapping, coding, and data standards at AHIMA.


  1. What is the proper code for a screening ultrasound?

  2. If screening Mammogram was performed and Dx Z12.31 was coded and Ultrasound of bilateral breasts was also performed on the same session, what would be the Dx for US?

  3. How about the patient that has had the mastectomy and she comes back in for a screening mammo. Is the dx code still the screening code then the cancer codes?

    1. Yes you would still continue to use Z12.31 with the cancer code and you can also add Z90.1* for the history of mastectomy.

  4. What if we have a patient coming in (per the physician order) for an annual screening mammogram but he is also listing dense breasts as a dx on the script (diagnosed on the previous screening performed a year earlier). To clarify the patient has had previous studies that resulted in the dx of dense breasts but no other findings. What is the proper diagnosis for subsequent annual screenings? Or does the dx of dense breasts eliminate screenings going forward? Seems there is a conflict in ICD-10; we can’t report both dx on a subsequent screening.

  5. If the patient presents for a screening mammogram (screening is the reason for the visit/mammogram) and also has a diagnostic mammogram performed under the same patient account number (same encounter) then yes the screening is the reason for visit and secondary code(s) are assigned as applicable as the reason for the diagnostic mammogram. Reference ICD-10-CM Official Guideline I.C.21.c.5) Screening. CPTs get a modifier.

  6. please clarify if both a screening and diagnostic is done on the same day the dx for screening stays the same on both and the CPTs get a modifier.

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