CPT code 71100 – Unilateral rib x-ray

Key takeaways

CPT Code 71100 covers a unilateral (one-sided) rib x-ray and requires a minimum of 2 views to bill correctly.

CPT 71101 is not the bilateral code. It is a unilateral rib series that adds a posteroanterior (PA) chest view, with at least three views.

Billing 71100 twice for a bilateral exam is incorrect. Use CPT 71110 when both sides are imaged, or 71111 when a PA chest view is included.

Missing laterality in the radiology report is the single most common reason 71100 claims are denied by payers.

Practice software such as Pabau keeps the order, diagnosis code, and claim together, so staff can check laterality and modifiers before submission.

CPT Code 71100: Official descriptor and procedure definition

CPT Code 71100 is defined by the American Medical Association as “Radiologic examination, ribs, unilateral; 2 views.” It sits in the Radiology section of CPT (70010-79999), within diagnostic radiology procedures of the chest (71045-71555).

The code applies when a clinician orders an x-ray of one side of the ribcage only. The imaging must capture two distinct projections of that side.

Two points trip up coders consistently. First, 71100 needs two views, so a single-view rib study billed under it is a documentation error and a denial risk. Second, the code explicitly covers ribs, not the chest.

Ordering a “chest x-ray with rib views” does not automatically make 71100 the right code. The clinical indication and the documented anatomical focus must be the ribs themselves.

What CPT Code 71100 covers: Clinical indications and ICD-10 pairings

CPT 71100 is appropriate when a clinician needs one side of the ribcage imaged to assess trauma, fracture, or pathology on that side. The most common clinical triggers are blunt chest trauma and a suspected rib fracture after a fall or motor vehicle accident. A metastatic workup for a one-sided lesion and pleuritic or costal pain with documented laterality also qualify.

The supporting ICD-10-CM code must reflect the same laterality as the x-ray order. Common pairings include:

• S22.31XA / S22.32XA – fracture of one rib, right or left side, initial encounter for closed fracture
• S22.31XD / S22.32XD – fracture of one rib, right or left side, subsequent encounter with routine healing
• S22.41XA / S22.42XA – multiple fractures of ribs, right or left side, initial encounter for closed fracture
• R07.81 – pleurodynia (pleuritic chest wall pain)
• R07.9 – chest pain, unspecified (when laterality is noted in the chart but not yet diagnosed)
• C79.51 – secondary malignant neoplasm of bone (suspected rib metastasis)

Payers increasingly apply automated edits that cross-check the ICD-10 laterality character against the documented side in the radiology report. A left-sided rib pain ICD-10 code paired with a report that says “right ribs imaged” will trigger a denial regardless of clinical logic.

Coders should confirm the ICD-10 laterality character matches the radiologist’s report before submission, not after. A bilateral diagnosis such as S22.43XA (multiple fractures of ribs, bilateral) points to a two-sided study, which is coded 71110 or 71111 rather than 71100.

CPT 71100 vs 71101, 71110 and 71111: Choosing the right rib x-ray code

CPT 71100 is one of four rib x-ray codes, and two questions decide between them. Were one or both sides of the ribcage imaged? And did the study include a posteroanterior (PA) chest view?

CPT 71101 causes the most confusion. Its descriptor still reads “unilateral,” so it never covers the second side of the ribcage. It applies when a one-sided rib series also includes a PA chest view, usually ordered to check the lungs for complications such as a pneumothorax.

When both sides are imaged, the study is reported with 71110, or with 71111 if a PA chest view is part of it. Billing 71100 twice on the same date of service, once per side, is incorrect coding. It typically triggers a duplicate-claim edit or a medical necessity denial, depending on the payer’s adjudication logic.

Adjacent codes: CPT Code 71100 vs chest x-ray codes 71045 and 71046

The chest x-ray codes and the rib codes are anatomically adjacent but clinically distinct. CPT 71100 images the ribs. CPT 71045 and 71046 image the chest cavity (lungs, heart, mediastinum). Reporting one in place of the other misstates the documented study, which creates compliance exposure in either direction.

If the only chest image is a PA view taken as part of a one-sided rib series, the whole study is coded 71101. The PA chest view is already in that descriptor, so a separate 71045 for the same view would report it twice.

Same-day billing of 71100 alongside 71045 or 71046 is sometimes appropriate when the clinical record documents a separate indication for each study. An example is a suspected rib fracture plus a separate pulmonary evaluation. NCCI edits may restrict same-day billing of rib and chest x-ray codes in certain scenarios. Check the current CMS NCCI table before billing both codes on the same date of service.

Professional vs technical component billing for CPT Code 71100

Radiology codes like CPT 71100 can be billed globally or split into two components, depending on who performs and interprets the study. Getting the split right prevents the most common modifier errors in radiology billing.

• Global billing (no modifier): Used when one billing entity both performs the x-ray and employs the radiologist who interprets it. The single 71100 line covers both the technical and professional work.
• Technical Component (Modifier TC): Used by the facility or independent imaging center that performs the x-ray but does not employ the interpreting radiologist. The TC modifier captures only the equipment, staff, and overhead costs.
• Professional Component (Modifier 26): Used by the radiologist or physician who interprets the image but does not own the equipment. Modifier 26 captures only the professional interpretation.

A common error occurs when a hospital outpatient department bills globally for 71100 while the independent radiologist group also bills globally. The result is a duplicate claim. The facility bills TC, the radiologist bills with Modifier 26, and together they equal the global payment. Neither party bills the full global unless they genuinely perform and interpret in-house.

Medicare reimbursement rates for CPT Code 71100

Medicare pays for CPT 71100 under the CMS Medicare Physician Fee Schedule, with rates adjusted by Geographic Practice Cost Index (GPCI) for each payment locality. The figures below reflect approximate national averages for the 2025 fee schedule year. Verify current rates in the CMS MPFS lookup tool before quoting any payment amount.

Private payer rates vary substantially from Medicare and may be negotiated as a percentage of the MPFS or as flat contracted rates. Practices should check payer contracts individually. The FastRVU lookup tool provides a quick reference for current RVU values and location-adjusted Medicare rates without requiring a paid subscription.

According to the American Medical Association, CPT codes are updated annually. Work RVU values for radiology codes, including 71100, can change in each year’s MPFS rulemaking cycle. Always confirm rates for the current fiscal year before setting billing expectations with clinical staff.

Prior authorization and payer requirements for CPT Code 71100

Rib x-rays under CPT 71100 are plain film studies, so they never fell under the Appropriate Use Criteria (AUC) program. The Protecting Access to Medicare Act (PAMA) created that program for advanced imaging such as CT, MRI, nuclear medicine, and PET. CMS paused it indefinitely and rescinded its regulations from January 1, 2024. No imaging modality, plain film included, currently faces an AUC requirement. Prior authorization rules still vary significantly by payer class.

• Medicare: Prior authorization is typically not required for plain film rib x-rays. However, medical necessity must be documented and a valid ICD-10 diagnosis code must support the clinical indication. Local Coverage Determinations (LCDs) for diagnostic radiology may apply depending on your MAC jurisdiction.
• Medicaid: Requirements vary by state. Some Medicaid managed care plans require authorization for any imaging beyond a defined visit-based allowance. Check your state’s Medicaid fee-for-service policy and any managed care plan contracts separately.
• Commercial payers: Many commercial plans do not require prior authorization for plain film x-rays. High-deductible plans and certain specialty networks may still impose utilization management rules. Verify with each payer before ordering.

The safest practice is to verify coverage and authorization requirements for each patient’s specific plan before the study is performed. MAC Local Coverage Determinations for outpatient diagnostic radiology are publicly available and worth reviewing for your jurisdiction. Pabau’s integration with the Claim.MD clearinghouse includes real-time eligibility verification. Front-desk staff can confirm a patient’s imaging coverage before the appointment instead of learning about it from a denied claim.

Documentation requirements to support CPT Code 71100

A clean 71100 claim requires six documentation elements. Missing any one of them is enough to trigger a denial or a request for additional information from the payer.

• Laterality: The order and the radiology report must both specify “left” or “right.” Vague language like “rib pain” without a documented side is the top denial trigger for this code.
• View count: The report must document at least two views of the imaged side. Single-view studies cannot be billed as 71100.
• Clinical indication: The ordering provider’s notes must document a clinical reason for the study that is supported by the ICD-10 code used on the claim. Trauma, fracture suspicion, and localized rib pain are the most common.
• Ordering physician NPI: The referring or ordering physician’s NPI must appear on the claim, particularly for facility-based studies where the ordering and performing entities differ.
• Radiologist interpretation: If Modifier 26 is appended, the radiologist’s signed interpretation report is required. An unsigned or addended-but-not-finalized report can delay payment.
• ICD-10 laterality match: The ICD-10-CM code’s laterality character must match the documented side in the radiology report. In rib fracture codes such as S22.31- and S22.32-, it is the 5th character. A mismatch triggers automated edits at adjudication.

Practices that route rib x-ray orders through integrated claims management software can build pre-submission checks. Those checks flag incomplete laterality, mismatched diagnosis codes, and missing view counts before the claim leaves the practice.

Common claim denial reasons for CPT Code 71100 and how to avoid them

The majority of 71100 denials stem from a small set of repeatable errors. Auditing for these seven patterns before submission catches most of them. When one slips through, the remittance names the cause with a claim adjustment reason code (CARC). Our guide to medical billing denial codes explains what each one asks you to fix.

How Pabau prevents CPT 71100 denials before submission

In many practices, the coder reads the radiology report and keys the code into a separate billing system. A missing side, a wrong view count, or the wrong rib code only surfaces when the denial arrives. By then, the radiologist has moved on and an addendum can take weeks.

Pabau keeps the imaging order, the ICD-10 selection, and the claim in the same patient record. Coding staff can check laterality, view count, and the choice between 71100, 71101, 71110, and 71111 while the study is still fresh.

Claims then go out through Claim.MD, our integrated US clearinghouse partner, which also handles eligibility checks and electronic remittance advice (ERA). Any denial that still comes back can be logged with its CARC reason code. It is then routed through a structured denial management workflow until it is resolved.

Stop losing revenue to preventable rib x-ray claim denials

Pabau keeps the radiology order, diagnosis code, and claim in one workflow. Your team can check laterality, view count, and the right rib code before 71100 claims go out.

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Conclusion

CPT Code 71100 has a short list of requirements, and every one of them lives in the radiology report. If the report names one side, documents two views, and shows no PA chest image, 71100 is the right code. If it doesn’t, fix the report or move to 71101, 71110, or 71111 before the claim goes out.

The trade-off is a minute of checking at the front of the process. That costs far less than chasing a radiologist for an addendum weeks after the denial lands.

Practices that connect radiology orders to their billing system make that check routine rather than dependent on one coder’s memory. To see how Pabau’s medical billing and claims tools keep rib x-ray claims clean, book a demo with the team.

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