An Overview of Colonoscopy Coding Guidelines

The ACA, which was passed in 2010, did a great many things, but this is what is relevant for colonoscopies: insurers must cover preventive services, like screenings and vaccines, without charging co-pays, deductibles, or coinsurance to encourage early detection and preventive care.

A screening colonoscopy should have no patient due amount for an insured patient. A deductible and co-insurance are both waived. However, if the physician does a diagnostic procedure (biopsy) or therapeutic procedure (removal of the polyp), the procedure is no longer considered a screening, resulting in a patient-due balance.
In that case, using the correct modifiers and sequencing the diagnosis codes correctly can increase the likelihood that the payer will still process the service as a screening, but there are no guarantees.
The ACA prohibited Medicare from charging a deductible for screening colonoscopies that converted from screening to diagnostic. However, Medicare still charges co-insurance for screening colonoscopies that convert to diagnostic or therapeutic services, i.e., removal of a polyp. In 2022, the co-insurance amount was 20%. As explained in the following point, this changed.
Co-insurance for planned colorectal screening services that become diagnostic or therapeutic will be phased out to 0 between 2023 and 2030. [1]

For dates of service in CYs:

- 2023–2026, coinsurance is 15%
- 2027–2029, coinsurance is 10%
- Starting 2030, no coinsurance

Screening Age and Non-invasive Coverage

In 2023, CMS lowered the age for screening from 50 to 45. This means that patients can get screened for CRC at 45 without a co-pay or deductible charged to them. Another update at that time clarified that if a patient has a non-invasive screening test (FOBT or MT-sDNA test ) and has a positive result, the subsequent colonoscopy will be processed as a screening test, not a diagnostic. In 2022, the colonoscopy would have been processed as a diagnostic test, thus exposing the patient to deductible and co-insurance amounts. [2]

From the 2023 MPFS Final Rule:

We also are exercising our authority in section 1861(pp)(1)(D) of the Act to expand coverage of CRC screening tests to include a follow-on screening colonoscopy after a noninvasive stool-based test returns a positive result. As noted earlier in the rule, the outcome of our more appropriate and complete approach to CRC screening will be that, in many cases, beneficiary cost sharing for both the initial non-invasive screening stool-based test and the follow-on screening colonoscopy test will not apply because both tests will be paid at 100 percent (no applicable copayment percentage) as specified preventive screening services under the statute.

For example, as related in a publication from 2023, when a diagnostic goes from preventative to diagnostic, you’ll append modifier PT to the diagnostic CPT code. If a patient has a screening, but a polyp is removed, you’d code 45385 (Colonoscopy, flexible; with the removal of tumor(s), polyp(s), or another lesion (s) by snare technique) and append modifier PT. Appending modifier PT to a procedure that started as a screening HCPCS code but converted to a diagnostic code will alleviate any out-of-pocket for the patient and keep the service covered as a preventive. [3]

PT Modifier definition: Colorectal cancer screening test; converted to diagnostic test or other procedure

Screening colonoscopy for CRC

Screening colonoscopy is a service with first-dollar coverage, which means that it is a screening test with an A or B rating from the US Preventive Services Task Force and should have no patient due amount.

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This seems simple, right? But Medicare complicates the issue by using different procedure codes than other payers for screening and a different modifier for screening procedures that become diagnostic or therapeutic.

Members login in to watch this brief overview, and download the slides for reference.

What is the Difference between a Screening Test and a Diagnostic Colonoscopy?

A screening test is a test 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. A diagnostic test is done in response to a sign or symptom to investigate and diagnose a condition. A patient with rectal bleeding and anemia for whom a colonoscopy has been ordered is having a diagnostic colonoscopy.

“Screening” describes a colonoscopy routinely performed on an asymptomatic person for the purpose of testing for the presence of colorectal cancer or colorectal polyps. Whether a polyp or cancer is ultimately found does not change the intent of the screening procedure.

As part of the Affordable Care Act (ACA), Medicare and third-party payers are required to cover services given an A or B rating by the U.S. Preventive Services Task Force (USPSTF) and process the claim as screening. However, a diagnostic colonoscopy is a test performed as a result of an abnormal finding, sign, or symptom. Medicare does not waive the co-pay and deductible when the intent of the visit is to perform a diagnostic colonoscopy. Medicare waives the deductible but not the co-pay when a procedure scheduled as a screening is converted to a diagnostic or therapeutic procedure.

Confounding this issue is the term “surveillance colonoscopy”—one performed at more frequent intervals than every ten years because the patient has a personal history of colonic polyps. Should this be billed as screening (in the absence of current signs/symptoms) or diagnostic, because it is being performed because of the personal history of the patient? Neither CPT^® nor CMS address this directly, but I will give my recommendations below, in Clinical Scenario five, at the end of this article. In my experience, surveillance is another word used by clinicians for screening. And, see the article on diagnosis coding for screening on CodingIntel; it provides references from the Coding Clinic.

Two Sets of Procedure Codes are Used for Screening Colonoscopy:

CPT^® code 45378

Colonoscopy, flexible, proximal to splenic flexure; diagnostic, with or without collection of specimen(s) by brushing or washing, with or without colon decompression (separate procedure)

and

Healthcare Common Procedural Coding System (HCPCS) codes G0105 and G0121

G0105 colorectal cancer screening; colonoscopy on individual at high risk)

G0121 (colorectal cancer screening; colonoscopy on individual not meeting the criteria for high risk.

Why are there two sets of codes in coding colonoscopy guidelines?

The Centers for Medicare and Medicaid Services (CMS) developed the HCPCS codes to differentiate between screening and diagnostic colonoscopies in the Medicare population.

Common diagnosis codes for colorectal cancer screening include:

Z12.11 (encounter for screening for malignant neoplasm of colon)
Z80.0 (family history of malignant neoplasm of digestive organs)
Z86.010 (personal history of colonic polyps).

Clinical scenario one:

A 70-year-old Medicare patient calls the surgeon’s office and requests a screening colonoscopy. The patient’s previous colonoscopy was at 59 years old and was normal. The patient has no history of polyps or colorectal cancer, and none of the patient’s siblings, parents, or children has a history of polyps or colorectal cancer. The patient is eligible for a screening colonoscopy. The reportable procedure and diagnoses include:

G0121, colorectal cancer screening; colonoscopy on individual not meeting the criteria for high risk
Z12.11, encounter for screening for malignant neoplasm of colon

The HCPCS code is the correct code to use—not the CPT^® code—because the patient is a Medicare patient. Additionally, G0121 is selected because the patient is not identified as high risk.

HCPCS and CPT® Screening Colonoscopy Codes
HCPCS/CPT^® code	Description
45378	Colonoscopy, flexible; diagnostic, including collection of specimen(s) by brushing or washing, when performed (separate procedure)
G0105	Colorectal cancer screening; colonoscopy on individual at high risk
G0121	Colorectal cancer screening; colonoscopy on individual not meeting the criteria for high risk

Common Colorectal Screening Diagnosis Codes
ICD-10-CM	Description
Z12.11	Encounter for screening for malignant neoplasm of colon
Z80.0	Family history of malignant neoplasm of digestive organs
Z86.010X	Personal history of colonic polyps (code to greatest specificity)

E/M Service Prior to a Screening Colonoscopy

Typically, procedure codes with 0, 10, or 90-day global periods include pre-work, intraoperative work, and post-operative work in the Relative Value Units (RVUs) assigned by the AMA and approved by CMS. As a result, CMS’ policy does not allow for payment of an Evaluation and Management (E/M) service prior to a screening colonoscopy. [4]

In 2005, the Medicare Administrative Carrier (MAC) for the state of Rhode Island explained the policy this way:

“Medicare does not cover an E/M prior to a screening colonoscopy. An item or service must have a defined benefit category in the law to be covered under Medicare. For example, physicians services are covered under section 1861(s)(1) of the Social Security Act. However, section 1862(a)(1)(A) states that no payment may be made for items or services that are not reasonable and necessary for the diagnosis or treatment of an illness or injury or to improve the functioning of a malformed body member.

In addition, section 1862(a)(7) prohibits payment for routine physical checkups. These sections prohibit payment for routine screening services, those services furnished in the absence of signs, symptoms, complaints, or personal history of disease or injury. … While the law specifically provides for a screening colonoscopy, it does not also specifically provide for a separate screening visit prior to the procedure. The Office of General Counsel (OGC) was consulted to determine if sections 1861(s)(2)(R) and 1861(pp) could be interpreted to allow separate payment for a pre- procedure screening visit in addition to the screening colonoscopy. The OGC advises that the statute does not provide for such a preprocedure screening visit.”

Medicare defines an E/M prior to a screening colonoscopy as routine, and thus non-covered. However, when the intent of the visit is a diagnostic colonoscopy, an E/M that takes place prior to the ordered procedure for a finding, sign, or symptom is a covered service.

Third-party payers who do not follow Medicare guidelines may reimburse a provider for an E/M service prior to a screening colonoscopy. There are no CPT guidelines for how to select a code based on medical decision making for a screening procedure. An option available to use is for the provider to document the time spent on that patient’s care for the day.

Screening Colonoscopy for Medicare Patients

Report a screening colonoscopy for a Medicare patient using G0105 (colorectal cancer screening; colonoscopy on individual at high risk) and G0121 (colorectal cancer screening; colonoscopy on individual not meeting the criteria for high risk).

Medicare beneficiaries without high risk factors are eligible for screening colonoscopy every ten years. Beneficiaries at high risk for developing colorectal cancer are eligible once every 24 months. Medicare considers an individual at high risk for developing colorectal cancer as one who has one or more of the following:

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

[5]

To report a screening colonoscopy on a patient not considered high risk for colorectal cancer, use HCPCS code G0121 and diagnosis code Z12.11 (encounter for screening for malignant neoplasm of the colon). To report screening on a Medicare beneficiary at high risk for colorectal cancer, use HCPCS G0105 and the appropriate diagnosis code that necessitates the more frequent screening.

Clinical scenario two:

A Medicare patient with a history of Crohn’s disease presents for a screening colonoscopy. Her most recent screening colonoscopy was 25 months ago. No abnormalities are found. Reportable procedures and diagnoses include:

G0105, Colorectal cancer screening; colonoscopy on individual at high risk
Z12.11, Encounter for screening for malignant neoplasm of colon
K50.80, Crohn’s disease of both small and large intestine without complications

Common ICD-10 diagnosis codes indicating high risk
Z85.038	Personal history of other malignant neoplasm of large intestine
Z85.048	Personal history of other malignant neoplasm of rectum, rectosigmoid junction, and anus
Z80.0	Family history of malignant neoplasm of digestive organs
Z86.010	Personal history of colonic polyps

Screening Colonoscopy for Medicare Patients that becomes Diagnostic or Therapeutic

It is not uncommon to remove one or more polyps at the time of a screening colonoscopy. Because the procedure was initiated as a screening, the screening diagnosis is primary, and the polyp(s) are secondary. Additionally, the surgeon does not report the screening colonoscopy HCPCS code but reports the appropriate code for the diagnostic or therapeutic procedure perfodmed, from CPT^® code range 45379—45392.

Colonoscopy CPT^® codes
CPT^® Code	Descriptor
45378	Colonoscopy; flexible, diagnostic, including collection of specimen (s) by brushing or washing, when performed (separate procedure)
45379	; with removal of foreign body (s)
45380	; with biopsy, single or multiple
45381	; with directed submucosal injection(s), any substance
45382	; with control of bleeding, any method
45388#	; with ablation of tumor(s), polyp(s), or other lesion(s) (includes pre- and post-dilation and guide wire passage, when performed)

45384	; with removal of tumor(s), polyp(s), or other lesion(s) by hot biopsy forceps
45385	; with removal of tumor(s), polyp(s), or other lesions by snare technique
45386	; with transendoscopic balloon dilation
45389	; with endoscopic stent placement (includes pre- and post-dilation and guide wire passage, when performed)
45390#	; with endoscopic mucosal resection
45391	; with endoscopic ultrasound examination limited to the rectum, sigmoid, descending, transverse, or ascending colon and cecum, and adjacent structures
45392	; with transendoscopic ultrasound guided intramural or transmural fine needle aspiration/biopsy(s), includes endoscopic ultrasound examination limited to the rectum, sigmoid, descending, transverse or ascending colon and cecum, and adjacent structures
45393	; with decompression (for pathologic distention) (eg, volvulus, megacolon), including placement of decompression tube, when performed
45398#	; with band ligation(s) (eg, hemorrhoids)

# = Resequenced Code

Modifier PT

CMS developed the PT modifier to indicate that a scheduled screening colonoscopy was converted to a diagnostic or therapeutic procedure.

Coding Tip: Be sure to add Modifier PT to the anesthesia service, too, as it informs Medicare that the anesthesia was intended for the screening procedure so the patient will not be charged a deductible, although a co-pay is due.

Screening Colonoscopy for Non-Medicare Patients

When reporting a screening colonoscopy on a non-Medicare patient, report CPT^® code 45378 and use the appropriate screening diagnosis code. Recall that as a result of the ACA, for patients covered by a group insurance policy that was purchased or renewed after September 2010 will have no co-pay or deductible unless the plan applied for grandfathered status.

Clinical scenario three:

A 52-year-old patient calls the surgeon’s office and requests a screening colonoscopy. The patient has never had a screening colonoscopy. The patient has no history of polyps, and none of the patient’s siblings, parents, or children have a history of polyps or colon cancer. The patient is eligible for a screening colonoscopy. Reportable procedure and diagnoses include:

45378, Colonoscopy, flexible, proximal to splenic flexure; diagnostic, with or without collection of specimen(s) by brushing or washing, with or without colon decompression (separate procedure)
Z12.11, Encounter for screening for malignant neoplasm of colon

Screening Colonoscopy for Non-Medicare Patients that becomes Diagnostic or Therapeutic

When a screening colonoscopy converts to a diagnostic or therapeutic procedure for a non-Medicare patient, the surgeon must document that the intent of the procedure was screening. This is required so that the patient’s insurance processes the claim without any out-of-pocket expense in accordance with the ACA.

CPT^® developed the 33 modifier for preventive services, for “when the primary purpose of the service is the delivery of an evidence-based service in accordance with a US Preventive Services Task Force A or B rating in effect and other preventive services identified in preventive services mandates (legislative or regulatory), the service may be identified by adding 33 to the procedure.” For example, if a surgeon performing a screening colonoscopy finds and removes a polyp with a snare, use CPT^® code 45385 and append modifier 33 to the CPT^® code.

Clinical scenario four:

The same 52- year-old patient from the previous example had an abnormal finding during the screening colonoscopy. The surgeon removes a polyp with a snare technique. Reportable procedure and diagnoses include:

45385-33, Colonoscopy, flexible, proximal to splenic flexure; with removal of tumor(s), polyp(s), or other lesions by snare technique
Z12.11, Encounter for screening for malignant neoplasm of colon
K63.5 Polyp of the colon

In this case, report Z12.11 as the primary diagnosis to indicate it was scheduled as a screening test and K63.5 as the secondary diagnosis. In addition to the primary Z-code, modifier 33 indicates the primary purpose of the procedure was screening, in accordance with the evidence-based practice as identified by USPSTF.

Diagnosis Code Ordering is Important for a Screening Procedure turned Diagnostic

When the intent of a colonoscopy is to screen for CRC, and findings result in a diagnostic or therapeutic service, the ordering of the diagnosis codes can affect how payers process the claim. There is considerable variation in how payers process claims, and the order of the diagnosis code may affect whether the patient has out-of-pocket expenses for the procedure. The appropriate screening diagnosis code should be placed in the first position on the claim form and the finding or condition diagnosis in the second position. It is important to verify a payer’s reporting preference to avoid payment denials.

Recall: there are two sets of procedure codes that describe colonoscopy services. Additionally, there are different preventive service modifiers required by Medicare and by other, third-party payers. The order of diagnosis coding can affect how a payer processes the claim and whether there is an out-of-pocket expense for the patient. Mastering the coding for each payer may result in lower claims processing costs, quicker payments, and fewer patient complaints.

Clinical scenario five:

At a routine screening, a patient is found to have an adenomatous polyp. The surgeon recommends that the patient return for a surveillance colonoscopy in three years. (The USPSTF recommendations do not address the frequency of repeat surveillance. The American Cancer Society does have recommendations.)

[6]

Is this test diagnostic or screening? How it is coded will determine the patient’s due amount. I suggest reporting the service with modifier 33.

Modifier 33–Preventive Services: when the primary purpose of the service is the delivery of an evidence-based service in accordance with a USPSTF A or B rating in effect and other preventive services identified in preventive services mandates (legislative or regulatory), the service may be identified by adding 33 to the procedure.

When reporting the diagnosis code, I would suggest reporting Z12.11 (encounter for screening for malignant neoplasm of the digestive organs) and Z86.010 (personal history of colonic polyps) second. The patient will probably need to appeal not paying a co-pay to their insurance company. See the CodingIntel article “Diagnosis coding for screening colonoscopy” for more detail.