Coverage of Colonoscopies Under the Affordable Care Act's Prevention Benefit

Appendix A – Different Approaches to Insurance Billing Codes for Screening Colonoscopy

Insurance billing codes for screening colonoscopy have two components. The first describes the procedure (CPT code) indicating the exact service that was provided. A family of CPT codes applies to colonoscopy. For example, code 45378 applies to a colonoscopy in which no polyp is detected, while codes 45380-45385 apply to colonoscopy that involves an intervention (e.g., 45385 is the code for colonoscopy with polypectomy.)   A second component of the code – either a CPT modifier or a separate diagnostic (ICD-9) code – can differentiate between colonoscopies that were initiated as screening and those that were not.

In response to the ACA’s new preventive services requirement, the American Medical Association, which maintains the CPT coding system, developed CPT modifier “33” to indicate when a procedure is initiated as a preventive service.   Modifier 33 can be added to the procedure code; so for a patient who sought a screening colonoscopy that resulted in polyp removal, the service would be coded as 45385-33. The doctor’s payment is increased when the polyp is removed to reflect the added work, but modifier 33 signals the insurance claims processing system to waive the deductible or other cost-sharing that might otherwise apply to the procedure.

Not all insurers and providers use the CPT modifier 33 today. Some instead use a combination of procedure codes and diagnostic codes to indicate a screening colonoscopy for which cost-sharing should be waived.

All medical bills require a second code (ICD-9 code) which describes the patient’s diagnosis or clinical condition.   In general, the ICD-9 coding system classifies the disease or injury associated with the procedure that was provided. A subset of ICD-9 codes (V codes) is used when the patient does not have a disease or injury, including when they seek preventive care. More than one diagnosis code may be submitted for a given procedure. For example, doctors could submit V76.51 as the primary diagnosis code for a screening colonoscopy that involves removal (CPT code 45385).   The V code indicates the screening intent of the procedure. The doctor might also submit as a secondary diagnostic code to indicate the type of polyp; for example 211.3 indicates a benign neoplasm of the colon was found. In this example, the primary diagnosis code indicates the intent of the procedure at its outset, while the secondary diagnosis code indicates the finding of the polyp.   However coding practices vary; some doctors might submit, or insurers might require, ICD-9 code 211.3 instead of the V code.

Medicare also uses CPT and ICD-9 codes, though its rules are somewhat different. Even before the ACA, Medicare waived the annual deductible for colorectal cancer screening. Medicare uses modifier “PT” to indicate a preventive service. In addition, when deductibles were first waived for colonoscopy, Medicare instructed providers to use a special “G” code (G0121) for screening colonoscopy for an average risk individual. However, Medicare instructs providers to use G codes only for screening colonoscopy in which no polyp is found. If a polyp is found and removed, providers are to use only a combination of CPT and ICD9 codes. If the patient came for a screening colonoscopy and was asymptomatic, CMS instructs providers to use V76.51 as the primary diagnosis code and 211.3 as the secondary diagnosis code.1 Under Medicare rules and federal law, cost sharing is only waived for screening colonoscopy when no polyp is removed. Legislation to change this rule has been introduced in Congress.


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