What Is the CPT Code for a Screening Colonoscopy?

Colorectal cancer screening is an essential part of preventive care. For providers, coding a screening colonoscopy correctly ensures proper reimbursement and avoids billing issues for patients. Let’s break down the relevant CPT and HCPCS codes, modifiers, and best practices.

1. What Is a Screening Colonoscopy?

A screening colonoscopy is performed on a patient without symptoms to detect colorectal cancer or precancerous polyps. Even if a polyp is removed, the intent remains preventive.

For practices, accurate coding not only prevents denials but also supports smooth revenue cycle management.

2. CPT / HCPCS Codes for Screening Colonoscopy

For Commercial / Medicaid Payers

• CPT 45378: Colonoscopy, diagnostic (with or without specimen collection).
• If polyps are removed, report the therapeutic CPT (e.g., 45385) and use modifier 33 to indicate the screening intent.

For Medicare Beneficiaries

• G0105: Screening colonoscopy for high-risk individuals.
• G0121: Screening colonoscopy for average-risk individuals.

If a screening colonoscopy becomes therapeutic, Medicare requires adding modifier PT. Full details are available in CMS guidance.

3. When a Screening Becomes Diagnostic

Often, a colonoscopy starts as a screening but turns diagnostic if abnormalities are found. In such cases:

• Use the therapeutic CPT code (like 45385).
• Keep the screening diagnosis code (e.g., Z12.11) as primary, and findings as secondary.
• Append modifier 33 (commercial payers) or PT (Medicare).

For specialty practices like gastroenterology medical billing, these distinctions are critical to avoid claim rejections.

4. Common Coding Pitfalls

• Not appending the correct modifier (33 or PT).
• Using the wrong diagnosis order.
• Failing to document intent (screening vs. diagnostic).

By working with experts in medical billing and coding, providers can reduce errors and improve reimbursement outcomes.

Final Thoughts

The CPT code for a screening colonoscopy varies depending on payer, patient risk factors, and whether findings are removed. Getting it right means:

• Patients benefit from preventive coverage.
• Practices avoid denials and audits.
• Revenue cycle efficiency improves.