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Bottoms Up: Screening Colonoscopy Coding From a Coder's Perspective

The following article is written by Jen Cohrs CPC, CPMA, CGIC, member of AAPC.


Colonoscopy coding is an art. There are many intricacies involved with the correct way to code a screening colonoscopy. Every provider, payor, plan and policy interprets the term "screening colonoscopy" different. So, what is the proper way to code a screening colonoscopy?


First, the basics: What is a colonoscopy? A colonoscopy is an endoscopic procedure using a flexible illuminated tube (colonoscope) inserted through the rectum advanced all the way to the cecum and/or terminal ileum to examine the entire colon for colorectal cancer, inflammatory bowel disease, adenomatous (pre-cancerous) colon polyps or other abnormalities/disorders/diseases of the lower digestive tract. A screening colonoscopy is performed on the asymptomatic, average risk patient for early detection and preventive measures against colorectal cancer. The American Cancer Society has established baseline guidelines as to whom and when a person should have a colonoscopy for preventive measures. Medicare and most commercial insurance companies follow some variation of the ACS guidelines. Coding for the colonoscopy should directly reflect why (level of risk or symptom) the procedure was performed, what tools were used (intervention), and what the outcome was (incidental findings).


The level of risk a patient faces regarding likelihood of developing colorectal cancer depends on many factors such as age, personal history, family history and race. The average-risk patient is typically screened for colorectal cancer via colonoscopy starting at age 50 and is without a personal history of adenomatous (pre-cancerous) colon polyps and colorectal cancer in any first-degree relative (parent, sibling, or child). After a patient has the procedure, documentation is reviewed, and if the outcome is unremarkable, it is time to code the procedure.


For professional claims and ambulatory surgery center facility claims, the diagnosis code for colorectal cancer screening is selected from the V code section in the ICD-9 book. V76.51 (Special screening for malignant neoplasm, colon) is used as the primary diagnosis for a screening colonoscopy. CPT 45378 (Colonoscopy, flexible, proximal to splenic flexure, diagnostic) is used for most for most commercial payers. Medicare differs from most commercial payors for procedure code selections for colorectal screenings and uses a HCPCS code. The HCPCS G-code selection is based on the patient's level of risk. For average risk, G0121 is to be used for Medicare claims, with V76.51 as the primary diagnosis.


What about high risk? A high-risk patient is either asymptomatic with a personal history of adenomatous colon polyps (V12.72), and/or a family history of colorectal cancer (V16.0) or adenomatous colon polyps (V19.8) in a first-degree relative (parent, sibling, or child), or has a personal history of a disease of the digestive system (colon cancer (V10.05)) or has a history of inflammatory bowel disease (Crohn's disease (555.0-555.9) or ulcerative colitis (556.0-556.9)*. A high-risk status warrants colorectal cancer screening at an interval less than one every 10 years.


For example, a Medicare patient who is at high-risk can have a screening colonoscopy performed once every 24 months. The HCPCS procedure code for the unremarkable high-risk screening colonoscopy is G0105. Commercial payors tend to follow Medicare guidelines, but all commercial payors vary on the coverage of the screening colonoscopy performed for a high-risk reason. Check with your local carriers to see if they accept G-codes rather than 45378 for screening colonoscopy.


One of the most common questions in many billing departments from patients is, "Why did you code my procedure as diagnostic? I have screening benefits and my colonoscopy was applied to my deductible. Can you re-file my claim as screening, so it gets paid?"

  • First, you need to assess the patient's level of risk. Was the patient average risk and the coder simply put the common finding of diverticulosis (562.10) as the primary diagnosis? If so, simply correct the claim to show V76.51 as the primary diagnosis and 562.10 as the secondary diagnosis, and re-file to the insurance company as a corrected claim along with a copy of the colonoscopy report to show the patient was in fact here for colorectal cancer screening, and diverticulosis was an incidental finding. The same process can be followed if a colon polyp is removed. Simply use V76.51 as the primary diagnosis and the colon polyp as the incidental finding, secondary diagnosis.
  • Second, you need to assess the tools used and if there are polyps or other abnormalities found during screening colonoscopy. The type of intervention performed during the examination determines the procedure code. If a colon polyp or abnormality is encountered, there are many different removal techniques that can take place. For example, snare polypectomy (45385), hot biopsy forceps polypectomy (45384), or argon beam plasma coagulation fulguration (45383) or cold biopsy forceps (45380) can all be performed for colon or rectal polyp removal. Also, each of these procedure codes is reported only once regardless of the number of polyps removed.
  • Third, you need to assess the actual medical necessity behind performing the colonoscopy in the first place. It would not be medically necessary for an asymptomatic average risk patient (V76.51) to be screened at a two, three or five-year interval. However, it might be medically necessary for an asymptomatic high-risk patient (V12.72, V16.0, etc.) to be screened every two, three or five years, therefore the diagnosis code used should reflect that.


Modifiers used in coding for colonoscopy have not changed; however, there are two new modifiers that directly impact this procedure. Effective Jan. 1, 2011, modifier -PT is to be used for fee-for service Medicare claims only, to show that an intervention was performed during the otherwise screening colonoscopy. By appending modifier -PT to the CPT code, this tells Medicare to waive the deductible for the patient for this procedure. Modifier -33 (preventive service) is attached to the CPT code to notify to commercial insurance companies that the colonoscopy started as a screening, but ended up diagnostic. Modifier -33 is new for 2011 and is not published in most CPT books, as it was approved for use by the American Medical Association after the 2011 books were printed. Check with your local carriers for specific use or requirements before using modifier -33.


Once the operative note is reviewed for indication, intervention and incidentals, then it is up to you to be sure to correctly code the procedure and the medically necessary diagnosis associated with it. In an ever-changing coding world in which we live it is easy to get caught up in what is the correct way to code, but remember this: Always revert back to medical necessity. It is the single most important element your claim should reflect.


*This is not an all-inclusive list and is only a brief summary of CMS policy GI-008. You can find the colorectal cancer screening guidelines for Medicare at


Ms. Cohrs has more than eight years of practical experience in healthcare, five years dedicated to the billing and coding field. She became a Certified Professional Coder (CPC) in 2007. She quickly followed with a specialty credential in gastrointestinal coding and medical record auditing and is a member of AAPC (



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