The Complexities of Coding Screening Colonoscopies in your ASC

Micah Swihart, CPC-A, ASC Procedural Coder

Colonoscopies can be a bit messy – both hypothetically and realistically. For years, the topic of colonoscopies has been a hot button issue, from coding to categorization, patient protocol and more. Today, we are going to take a look at the types of colonoscopies and some potential scenarios you may face when coding a colonoscopy procedure in your ASC.


A screening colonoscopy is a simple procedure performed on asymptomatic patients every 10 years once they reach the age of 50. Low-risk patients will have no personal history of colon cancer, high-risk gastrointestinal disease, or polyps nor a family history of colon cancer in a first degree relative like a parent or sister. A patient that is high-risk will have one of those conditions or histories and will be eligible for screening benefits more frequently (usually 2-year intervals) and at a younger age than 50, depending on the insurance. The purpose of a screening colonoscopy is to check for potential signs of colon cancer.

Screening colonoscopies are covered by insurance; most insurances cover one colonoscopy every 10 years for low-risk or 2 years for high-risk.


A type of screening, the term surveillance colonoscopy is used to specify a screening performed on a high-risk patient who has a history of colon polyps or colon cancer. A high-risk screening and a surveillance colonoscopy are very similar, but a surveillance is usually used to describe a patient who has had colon polyps, not a family history. Depending on the patient’s insurance, surveillance colonoscopies may be covered as frequently as every 12-24 months.

Surveillance colonoscopies are covered by insurance; the frequency of coverage is dependent different aspects of the patient’s colon health, and will vary by carrier.


When a patient shares concerns with their physician of bowel changes, bleeding, significant abdominal pain or other concerning symptoms, a diagnostic colonoscopy will be performed. The purpose of this procedure is to find the source of the concern and treat or study the findings, like a biopsy of tissue/polyps.

Diagnostic colonoscopies are not covered by insurance in the way screenings are; the patient will see patient responsibility at differing rates based on their insurance carrier and the status of their deductible / out-of-pocket maximum.


A follow-up colonoscopy will typically take place after a previous colonoscopy leads to a diagnosis / concern, or a polyp was unable to be fully removed. Most often, a follow-up colonoscopy will take place within the 3-6 months following the initial procedure.

Follow-up colonoscopies are not covered by insurance in the way screenings are; the patient will see patient responsibility at differing rates based on their insurance carrier and the status of their deductible / out-of-pocket maximum.


In 2018, Medicare released updated special reimbursement levels for canceled colonoscopies. This means that if, for whatever reason, a colonoscopy cannot be completed once the scope begins, the procedure will be paid for at a unique rate, and the patient will still be eligible to return for a successful screening colonoscopy.

Per the Center for Medicare & Medicaid Services (CMS), a canceled colonoscopy is defined as a diagnostic or screening endoscopic procedure on a patient who is scheduled and prepared for a total colonoscopy, where the physician is unable to advance the colonoscope to the cecum or colon-small intestine anastomosis due to unforeseen circumstances. To signify a canceled colonoscopy, the modifier 53 (discontinued procedure) must be attached or 73 / 74 for ambulatory surgery centers.

Plot Twist:

We only wish it was that black and white. When it comes to colonoscopies, things can change at the drop of a hat based on operative note wording and even things that take place during procedure.

For example, did you know a screening colonoscopy can become diagnostic once the patient is on the table? If a polyp or other area of concern is discovered during the scope, the procedure will become diagnostic; but, due to starting off as a screening, some screening benefits will apply, placing a lesser financial responsibility on the patient than if they had come in for a diagnostic procedure from the start.

Also, a patient may want a screening, but they have to meet the age eligibility requirements of their insurance. Most insurances only offer low-risk screening benefits to patients 50 or older, so a patient that is 49 can be denied a screening benefit and end up with the full cost of a screening left to patient responsibility.

Another one? Yes, we have more. The screening status of a procedure can change based on the verbiage used in the operative note, too. If a physician notates the procedure as a screening, but mentions the patient has had rectal bleeding, the acknowledgement of a symptom will cause the coding to turn diagnostic due to the existing concern (aka the patient is not asymptomatic). By simply including proper terminology, the physician can nip this coding crisis in the bud by stating that the rectal bleeding is ‘clinically insignificant’ (yes, we hope for those words exactly). That would signify that the rectal bleeding is not grounds for a diagnostic colonoscopy to be performed to find the cause or the cause is known and not a significant issue that would require treatment, surgical or otherwise; therefore, it is warranted for the physician to have continued with the planned screening colonoscopy.

When it comes to coding screening colonoscopies, there are a handful of codes that are used:


  • G0121- Colorectal cancer screening (non-high-risk)
  • G0105-Colorectal cancer screening (high-risk)

Commercial Payor’s

  • 45378- Colonoscopy, flexible, diagnostic, including the collection of specimens by brushing or washing when performed

ICD-10 Coding for Colonoscopies

ICD-10 coding can be tricky. There are payors that accept the Z12.11 (encounter for screening for malignant neoplasm of colon) in the first coding position, while other payors either require this diagnosis in a subsequent position behind family history codes or prefer to see the Z12.11 left off the claim entirely. Please check with your Fiscal Intermediaries for coding guidelines.

Let’s Look at ICD-10 Examples:

Bill turned 50 this past March, and comes in for his first screening colonoscopy. He has no symptoms or history, but during the procedure a polyp is found and biopsied.

Therefore: List Z12.11 first (to indicate a screening diagnosis is present) with polyp diagnosis subsequently as well as any incidental findings.

Lisa arrives for her screening colonoscopy, and shares with her physician that she has some concerns regarding recent changes to her bowel habits that are significant. These concerns now become the main focus of the colonoscopy if it is carried through, as a screening is only on asymptomatic patients.

Therefore: The concerning symptom(s) causes the procedure to turn from a screening to diagnostic prior to the procedure, therefore the symptom or finding is the primary diagnosis, i.e. change in bowel habits.

Jack had a colonoscopy 6 months ago, where an adenomatous polyp was found; he has now returned for a follow-up colonoscopy to check for polyp recurrence.

Therefore: If the follow-up colonoscopy was performed after completed treatment for conditions other than malignant neoplasm, list first Z09; if performed after removal of the malignancy and completed treatment for malignant neoplasm, list first Z08.

Disclaimer: Patients may still receive bills for anesthesia or other services utilized; the information provided speaks only to the coding of the colonoscopy itself.

Now, let’s modify.

Of course, as things change, modifiers become necessary to properly code the procedure and related outcomes. Take a look at some common modifiers and when they would be utilized:

The Preventative Service Modifier

Modifier-33 for Preventative Procedures:

  • Developed to indicate that a procedure was a screening with the 33-modifier appended to the diagnostic procedure(s). It is used in conjunction with codes like 45380 to denote that the procedure began as a screening and converted to diagnostic once the biopsy was performed.
  • Report to non-Medicare payers

PT Modifier:

  • Reported to Medicare only
  • Used only as a screening procedure converting to diagnostic modifier
  • Appended to the first CPT code regardless of amount of the CPTs billed
  • Informs Medicare that service performed was for a screening and does not charge a co-pay or deductible to the patient
  • Other Medicare ‘product’ carriers may accept the PT modifier

As always, scenarios can change at the drop of the hat, and not all payors are the same. We strongly encourage you to check with your Medicare and Commercial Payor policies for up-to-date compliant coding guidelines.

Have questions about coding for colonoscopies? Let’s chat! Give us a call at 1(855)208-5566 or email us at today!

Ready to make the change and outsource your ASC’s coding? Check out our Full Service Coding Solutions and let in2itive lend a hand.

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