Code Colonoscopies With Precision

Code Colonoscopies With Precision

Accurate billing of these procedures requires attention to detail.

Colonoscopy is a medical procedure in which the physician inserts a long, flexible, tubular instrument called a colonoscope into the patient’s anus to examine the lining of the entire colon for abnormalities and disease conditions. This type of test may be performed as a colorectal cancer preventive screening, for surveillance reasons, or for diagnostic/therapeutic purposes. Here’s what you need to know to correctly code colonoscopies for all four encounter types.

What Type of Colonoscopy Is It?

The first detail to consider is the purpose of the encounter. Colonoscopies fall into four basic encounter types:

Screening colonoscopy is provided to a patient in the absence of signs or symptoms based on the patient’s age, gender, medical history, and family history according to medical guidelines. It is defined by the population on which the test is performed, not the results or findings of the test. As such, “screening” describes a colonoscopy that is routinely performed on an asymptomatic person for the purpose of testing for the presence of colorectal cancer or colorectal polyps.

Diagnostic colonoscopy is performed when the patient has physical symptoms such as rectal bleeding or pain and the test is necessary to either rule out or confirm a suspected condition. Signs and symptoms are used to explain the reason for the test.

Therapeutic colonoscopy is performed when the abnormalities are treated for the purpose of biopsy, tumor ablation, or other therapy.

Surveillance colonoscopy is when the patient is asymptomatic but has a personal history of gastrointestinal disease, colon polyps, or cancer. Technically, this is a screening test with different diagnostic coding and frequency guidelines.

Coding Colonoscopies

In knowing the reason for the encounter — preventive, diagnostic, therapeutic, or surveillance — you can select the appropriate procedure code based on the patient’s age, risk for colorectal cancer, and insurance (not to mention fee schedule).

Screening Colonoscopy

Medicare coverage for preventive colonoscopies applies to patients aged 50 and older. As of 2022, the majority of commercial insurances cover screening colonoscopy for patients aged 45 and older. And a few payers cover even earlier for individuals at high risk for colorectal cancer.

For commercial and Medicaid patients, report CPT® code 45378 Colonoscopy, flexible; diagnostic, including collection of specimens(s) by brushing or washing, when performed (separate procedure). Append modifier 33 Preventive service to the procedure code to trigger the preventive benefits (no cost-sharing) to the patient.

Append modifier PT A colorectal cancer screening test converted to diagnostic test or other procedure to the procedure code if a screening turned into a diagnostic procedure. This does not waive Medicare patients’ 20 percent coinsurance and/or a copay, but it will waive the deductible.

For Medicare patients, report HCPCS Level II code G0105 Colorectal cancer screening; colonoscopy on individual at high risk or G0121 Colorectal cancer screening; colonoscopy on individual not meeting criteria for high risk, as appropriate. Modifier 33 is not used on G0121 or G0105 since screening is already indicated in the code descriptions.

As you can see, you must know whether a Medicare patient is at high risk for colorectal cancer to select the right screening code. Per the Medicare Claims Processing Manual (Pub 104, Ch.18, Sec. 60), an individual at high risk for colorectal cancer has:

  • A personal history of adenomatous polyps, colorectal cancer, or inflammatory bowel disease, including Crohn’s disease and ulcerative colitis; and/or
  • A family history of familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer or a close relative (sibling, parent, or child) who has had colorectal cancer or an adenomatous polyp.

Note the words in bold. These Medicare guidelines are often overlooked and, if not followed, will result in claim denials. Commercial payers may allow additional levels of family history, so always check policies for non-Medicare patients.

Per the ICD-10-CM guidelines, “A screening code may be a first-listed code if the reason for the visit is specifically for the screening exam.” That code would be Z12.11 Encounter for screening for malignant neoplasm of colon. To indicate risk, code selection will depend on the documented patient history (see the Medicare Administrative Contractor’s local coverage determination for colonoscopy for a complete list of diagnosis codes indicating high risk that are applicable to G0105). To indicate a screening colonoscopy is for surveillance of a previous problem, be sure to report the applicable history code, provided it is supported in the medical record.

Another consideration is frequency. Medicare covers screening colonoscopy for patients at normal risk for colorectal cancer once every 120 months (10 years) or 48 months after a previous sigmoidoscopy and once every 24 months for patients who are at high risk and/or require surveillance after findings from a previous screening. Per Pub. 100-04, Medicare Claims Processing Manual, Ch.18, Sec. 60, start the “count beginning with the month after the month in which a previous test/procedure was performed.” In other words, if the test was performed in March, begin counting from April.

Diagnostic/Therapeutic Colonoscopy

Report CPT® code 45378 for diagnostic colonoscopy if the scope reaches to the cecum; no modifier is allowed (see Figure 1). CPT® instructs you to append modifier 53 Discontinued procedure to the code if the scope goes beyond the splenic flexure, but not all the way to the cecum. If the scope does not reach the splenic flexure, then it is considered a flexible sigmoidoscopy, reported with code 45330 Sigmoidoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure). As you can see, proper coding hinges on the physician documenting that information.

If therapeutic measures, such as polyp removal, are performed, select the colonoscopy code that most accurately describes what was done. Append modifier 52 Reduced services to the code if the scope extends beyond the splenic flexure, but not as far as the cecum.

According to ICD-10-CM/PCS Coding Clinic (First Quarter 2017), whenever a screening exam is performed, the screening code is the first listed, even if an additional procedure is performed as a result of the screening. In the event a screening turns diagnostic, also code the finding(s).

Note: When submitting a claim for the facility fee associated with the procedure, ambulatory surgical centers (ASCs) should append the colonoscopy code with modifier 73 Procedure terminated/discontinued before anesthesia is provided or 74 Procedure terminated/discontinued after anesthesia is induced or the procedure is initiated, as appropriate. (See Pub. 100-04, Medicare Claims Processing Manual, Ch. 4, Sec. 20.6.4.)

Code by Example

Let’s look at a few coding examples for various colorectal cancer screening encounters.

Scenario 1:

Indication: Family history of colon cancer

Procedure performed: Screening colonoscopy

Coding: G0105, Z80.0 for Medicare patients (no cost-sharing)

              45378-33, Z80.0 for Medicaid and commercial patients

Rationale: For Medicaid and commercial patients, append modifier 33 to the CPT® code to eliminate patient cost-sharing (copay, coinsurance, and deductible).

Scenario 2:

Indication: Iron deficiency anemia, screening colon

Procedure performed: Colonoscopy

Coding: 45378, D50.9, Z12.11

Rationale: Screening is always performed on asymptomatic patients. As the reason for the visit is iron deficiency anemia, the test would be considered diagnostic even though a screening colonoscopy is specified. This scenario is considered a diagnostic colonoscopy so it is coded without modifiers 33/PT and the diagnosis is sequenced before the encounter code.

Scenario 3:

Indication: Colon screening on average risk patient

Post-endoscopy findings: Polyps in the cecum and sigmoid colon

Procedure performed: Colonoscopy with removal of cecal and sigmoid polyp by snare technique

Coding: 45385-33, Z12.11, D12.0, D12.5 or K63.5 (non-Medicare)

              45385-PT, Z12.11, D12.0, D12.54 or K63.5 (Medicare)

Rationale: The intent of the study was screening colonoscopy, but a polyp was removed during the procedure, which converted the screening colonoscopy to a diagnostic/therapeutic colonoscopy. Report the appropriate CPT® code with modifier 33/PT appended, depending on the payer. The screening code (Z12.11) would be sequenced first, followed by the findings. Also, once the polyp is removed, the follow-up visit should not be coded with K63.5 Polyp of colon, but rather Z86.010 Personal history of colonic polyps.

Don’t Overlook Anesthesia

In most cases, anesthesia is used when performing colonoscopies. For a screening colonoscopy, this service may be reported separately with CPT® code 00812 Anesthesia for lower intestinal endoscopic procedures, endoscope introduced distal to duodenum; screening colonoscopy (Medicare coinsurance and deductible are also waived). When a screening colonoscopy turns into a diagnostic colonoscopy, report the anesthesia service with CPT® 00811 Anesthesia for lower intestinal endoscopic procedures, endoscope introduced distal to duodenum; not otherwise specified with modifier PT. Appending modifier PT will waive the Medicare deductible but not the coinsurance. Moderate sedation is reported with HCPCS Level II code G0500 or, if warranted, CPT® code 99152-33 and 99153-33 based on time.

Can a Pre-screening Visit Be Billed?

Medicare does not cover a pre-procedure visit for a screening colonoscopy. However, a few of the commercial insurances will cover the visit with code S0285 Colonoscopy consultation performed prior to a screening colonoscopy procedure. You will need to check the payer’s policy.

Other Colorectal Cancer Screening

As an alternative to colonoscopy, Medicare covers additional types of colorectal cancer screening tests.

  • Fecal occult blood tests (FOBTs) – once every 12 months.
    • Medicare covers the Cologuard™ multi-target stool DNA (MT-sDNA) test once every three years for patients aged 50-85 years who are asymptomatic and at average risk for colorectal cancer. For claims with dates of service on or after Jan. 2, 2016, report with CPT® code 81528 Oncology (colorectal) screening, quantitative real-time target and signal amplification of 10 DNA markers (KRAS mutations, promoter methylation of NDRG4 and BMP3) and fecal hemoglobin, utilizing stool, algorithm reported as a positive or negative result.
    • For claims with dates of service on or after Jan. 19. 2021, blood-based biomarker tests are paid under the Clinical Laboratory Fee Schedule with HCPCS Level II code G0327 Colorectal cancer screening; blood-based biomarker.
  • Screening flexible sigmoidoscopy – once every 48 months or 119 months for average-risk patients who have received a screening colonoscopy in the past 10 years.
    • G0104 Colorectal cancer screening; flexible sigmoidoscopy
  • Screening barium enema – once every 48 months for average-risk patients or once every 24 months for high-risk patients.
    • G0106 Colorectal cancer screening; alternative to G0104, screening sigmoidoscopy, barium enema and G0120 Colorectal cancer screening; alternative to G0105, screening colonoscopy, barium enema

As you can see, it’s important to note a patient’s risk for colorectal cancer, as it will determine how often Medicare will cover a test.

Update (May 4, 2022): Please see MLN Matters article MM12656 for changes to Medicare coinsurance for additional procedures furnished during the same clinical encounter as certain colorectal cancer screening tests.


Fletcher, Terry A. BS, CPC, CCC, CEMC, CCS, CCS-P, CMC, CMSCS, ACS-CA, SCP-CA, QMGC, QMCRC, QMPM, Gastroenterology Coding Reference Guide

Shruthi Sargur Ravindranath
Latest posts by Shruthi Sargur Ravindranath (see all)

About Has 2 Posts

Shruthi Sargur Ravindranath, M.Sc, CPC, has more than 14 years of experience in medical coding and a master’s in zoology. She is associated with Vitalaxis, Inc., as senior coding manager. Ravindranath is a member of the Bangalore, India, local chapter. She is experienced in multiple specialties including E/M, gastroenterology, surgery, anesthesia, internal medicine, general surgery, and radiology.

22 Responses to “Code Colonoscopies With Precision”

  1. Stacy Bedow says:

    I have a question for a screening colonoscopy: If the scope goes past the splenic flexure and cancelled because of poor bowel prep, or other reason, would you use the “G” code with modifier -74 for an OP facility? We are being told to use the G codes with a modifier 74 if the procedure is cancelled. thank you for any additional information.

  2. Rita R says:

    Could you please explain how to bill a colonoscopy for some one with a history of colon polyps, Z86010. There seems to be some confusion about whether you bill it Z1211, Z86010. Or just Z86010

  3. Carol Viger says:

    Patient had been billed CPT 45380 Intestinal Exam and 43239 Scope exam with biopsy, G0500 Sedation by doctor, 99153 Sedation with observ. Patient age 29, experiencing many GI symptoms including chronic diarrhea, gas, upper GI stomach upset, indigestion etc. Several cousins with confirmed diagnosis of Celiac disease. (Previous screening blood test was negative). There was a statement from the Pathologist with a diagnosis – Pathology report same day “consistent with Lymphocytic Colitis” Dx used was K529 Inflammation of stomach and intestine.

    The plan paid $1509 of the Plan Allowed Amount of $2386, however the codes indicated “Not a Covered Service” (not medically necessary). The patient was left with $877 bill – any ideas on how this patient bill could be reduced?

  4. Chastity Omondi says:

    We had received denials for Z12.11 in the secondary position. When I looked at the denial cases all of them had polyp findings and per the tabular tip under Z12.11, I recommended resubmitting without Z17.11 but with the polyp findings. Is this incorrect?

  5. MS says:

    Nice recap for those not familiar with GI. Guess I’ve been doing my coding per your report. Thank you

  6. Carma Smith says:

    Thank you for this information regarding Colonoscopy procedures. As a new coder, this knowledge is great to have handy to read over a few times.

  7. Lee-Fifield says:

    Carol, your question falls outside the scope of this article. Please try posting your question on our forums.

  8. Lee-Fifield says:

    Chastity, if the patient is coming for a screening colonoscopy, then Z12.11 should be sequenced as PDx followed by findings provided there is no LCD list. Also, if Z code is removed, then the patient would be losing the screening benefit. However, I would need to know the exact denial reason to answer this question along with MAC and state.

  9. Lee-Fifield says:

    Rita, usually Z12.11 is not used when there are high-risk codes (Z86.010, Z83.71, Z80.0…).

  10. Lee-Fifield says:

    Stacy, modifier 74 is not applicable for screening colonoscopy G code, so for the cancelled or discontinued screening cases you need to bill with modifier 53.

  11. Joanne says:

    Thank you for this article, the diagram is perfect!
    Question – What modifier would be appropriate if patient is having a screening (or a surveillance) colonoscopy, scope goes to the cecum and a polyp is removed, however, prep is poor and not everything can be visualized and doctor wants to repeat in a month with longer prep. He did not discontinue the procedure at any point. Would this be a 53 or 52?
    Thank you in advance for your help!

  12. Lee-Fifield says:

    Joanne, for help with coding a particular scenario, you may want to post your question in our forums or utilize AAPC’s Ask an Expert service.

  13. Donna says:

    A traditional medicare insured patient, with a positive cologuard, underwent colonoscopy which resulted in negative findings. Do we use CPT 45378 or G0121, or G0105? Thank you.

  14. Linda says:

    Donna, you would bill g0121

  15. Melissa says:

    Is modifier -33 required for code 45378 when a commercial patient only has a screening done? Doesn’t the Z12.11 code trigger that the exam was a screening? I understand some payors require the -33 be on when submitted with 45378 but I do not think this is the case with ALL commercial screenings.

  16. Lee-Fifield says:

    For a screening colonoscopy: For commercial and Medicaid patients, report CPT® code 45378 Colonoscopy, flexible; diagnostic, including collection of specimens(s) by brushing or washing, when performed (separate procedure). Append modifier 33 Preventive service to the procedure code to trigger the preventive benefits (no cost-sharing) to the patient.

  17. Mary says:

    Hello. This is great information!
    Question please: can I bill the insurance for a follow up visit post colonoscopy screening if the findings are adenomas ex tubular adenomas.

  18. shelly smith says:

    What if 2 polyps are removed by 2 different means (snare, hot bx) do you put mod- PT and Z code as primary on both lines or just one?

  19. Donna Attery-Grant CPC, CGIC says:

    Answer to: What if 2 polyps are removed by 2 different means (snare, hot bx) do you put mod- PT and Z code as primary on both lines or just one?
    Medicare INS; 45385-PT, 45384-59-PT with Dx Z12.11, K 63.5, K62.1
    Commerical INS; 45385-33, 45384-59-33 with Dx Z12.11, K635, k62.1

  20. Donna Attery-Grant CPC, CGIC says:

    45385-w/PT or 33
    45384- 59 w/PT or 33 plus Z12.11 and the polyp’s code
    Medicare ins is PT
    Commercial is 33

  21. Jill Stamp says:

    A Medicare Patient has a colonoscopy – Pre Op Dx: History of Tubular Adenoma – Post Op Dx:Diverticulosis and History of Tubular Adenoma.
    Should this be billed as 45378 diagnostic or G0105 High risk screening?

  22. Renee Dustman says:

    According to the guidance in the article, you would report G0105. “For Medicare patients, report HCPCS Level II code G0105 Colorectal cancer screening; colonoscopy on individual at high risk” and “Per the Medicare Claims Processing Manual (Pub 104, Ch.18, Sec. 60), an individual at high risk for colorectal cancer has:
    A personal history of adenomatous polyps…”