G0121 - Colonoscopy screening for colon cancer in average-risk individuals

Healthcare Common Procedure Coding System

Last updated: 11/28/2025

What is a HCPCS Code?

HCPCS (Healthcare Common Procedure Coding System) codes are used to identify medical procedures, supplies, and services for billing purposes. These codes help standardize how healthcare services are reported and billed across different providers and insurance companies.

Detailed Description

This code represents a colonoscopy procedure performed specifically to screen for colorectal (colon and rectal) cancer in individuals who are considered average risk. This means the patient does not have factors that would classify them as high risk for developing colorectal cancer, such as a strong family history, personal history of polyps or inflammatory bowel disease, or certain genetic conditions. The colonoscopy is done as a preventive measure to detect cancer or precancerous changes early, when treatment is most effective.

Additional Information

This is specifically for screening purposes in average-risk patients. Different codes may apply for high-risk patients or diagnostic procedures.

Category

Preventive Care/Cancer Screening

Medical Specialty

Gastroenterology

Expected Costs

Your actual cost will depend on your insurance coverage, provider location, and specific circumstances.

What's Required Before This

  • Patient must be classified as average risk (not high risk) for colorectal cancer

What to Expect After

  • Follow screening guidelines based on results
  • Repeat screening intervals as recommended by physician

Why Understanding This Code Matters

On Your Medical Bill

This code appears on your medical bills to identify the specific service, procedure, drug, or medical diagnosis you received. Understanding what it means helps you verify you're being charged correctly and know what to expect.

For Your Health

Knowing what this code represents helps you understand your treatment plan, ask better questions during appointments, and track your healthcare journey more effectively.

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