Radiology Question for the Week of February 2, 2026

Question:

Ordered as a bilateral complete breast ultrasound, what is the proper code assignment? Complete real-time ultrasonography of the left breast was performed. Dense tissue is seen throughout. A 4 mm simple cyst is identified at the 12:00 position, 2 cm from the nipple. No concerning solid mass is seen in the left breast. A prominent left axillary lymph node measuring 9 mm in short axis is noted. Ultrasonography of the right chest wall and axilla was performed. No concerning lesion is identified.

Answer:

For this encounter, code assignment must be based on what was actually imaged and documented—not on the ordered exam.

• Left Side: The report states that a complete real-time ultrasound of the left breast was performed, with evaluation of breast tissue and axilla. This supports 76641-LT (complete unilateral breast ultrasound).
• Right Side: The documented service is ultrasonography of the right chest wall and axilla, with no description of right breast tissue, retroareolar structures, ducts, or parenchyma. Because breast anatomy was not evaluated, this does not meet the requirements for a breast ultrasound code (76641/76642).

Under AMA guidance (including Clinical Examples in Radiology), imaging of the chest wall or areas outside the breast should be reported with 76604 (ultrasound, chest), even if the order was for a bilateral breast ultrasound. Coding must follow the service performed.

Correct Coding Based on Documentation:

• 76641-LT — Complete left breast ultrasound
• 76604-RT — Right chest wall ultrasound

A bilateral breast ultrasound code cannot be assigned because a right breast ultrasound was not performed or adequately documented. If the intent was to evaluate the right breast, the provider would need to amend the note to include breast-specific imaging findings. For these scenarios, the best approach is to submit a provider clarification query so we can ensure the documentation fully supports the service.