This coding exercise explains the definition of a screening colonoscopy, appropriate use of modifier 33, and the specific CPT and ICD-10-CM codes assigned for the screening colonoscopy with polyp removal by snare. 

ICD-10-CM and CPT coding for preventive screening exam in a non-medicare patient

Question:  A 60-year-old female patient presents to the outpatient surgery area for a screening colonoscopy. She has no signs or symptoms, nor any personal or family history of polyps or colorectal cancer.

The surgeon inserts a flexible colonoscope into the rectum and advances it through the colon to the cecum. Two polyps are identified. A wire snare loop is slipped around each polyp and the loop is heated to shave off and cauterize the polyps. The mucosal surfaces are observed and no other abnormalities are found. The colonoscope is then removed.

This is a non-Medicare patient. Assign the correct CPT code(s) and ICD-10-CM code(s).


CPT: 45385-33

ICD-10-CM: Z12.11, K63.5

CPT Code

According to the CPT 2019 Professional Edition, a colonoscopy is the examination of the entire colon, from the rectum to the cecum, and may include an examination of the terminal ileum or small intestine proximal to an anastomosis.

Anastomosis is the surgical connection of two structures. The connection is commonly created between tubular structures such as blood vessels or loops of intestine, according to the U.S National Library of Medicine/MedlinePlus.

A screening colonoscopy is considered a preventive service and is performed on a patient without symptoms. Screening exams for non-Medicare patients are reported using CPT conventions, while screening exams for Medicare patients are reported using HCPCS codes (G0105, G1021).

In the CPT coding manual Index, look up Colonoscopy, Flexible, Removal, Polyp, 45384, 45385. Verified in the Tabular, 45385 refers to Colonoscopy, flexible; with removal of tumor(s), polyp(s), or other lesion(s) by snare technique. 

Even though two polyps were removed in the snare technique, CPT code 45385 should only be reported once.

Per AMA Guidelines:

(Do not report 45385 in conjunction with 45390 for the same lesion)

(Do not report 45385 in conjunction with 45378)

(For endoscopic mucosal resection, use 45390)

Modifier 33 should be appended to a preventive screening exam code for a non-Medicare patient. It should also be appended to a therapeutic screening code, as is the case here with the colonoscopy and removal of polyp(s) (45385-33). This modifier tells the payor that the therapeutic procedure should be reimbursed without regard to a patient’s copayment or deductible.  

The CPT coding manual gives the following description for Modifier 33:

Preventive service; 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 separately reported services specifically identified as preventive, the modifier should not be used.

(CPT code 45384 is incorrect, because the code description indicates the polyps were removed by hot biopsy forceps.)

ICD-10-CM Codes

In the 2019 ICD-10-CM coding manual Index, look up Screening, colonoscopy Z12.11. Verified in the Tabular, Z12.11 refers to Encounter for screening for malignant neoplasm of colon (or Encounter for screening colonoscopy NOS).

There is a note at Z12:

Screening is the testing for disease or disease precursors in asymptomatic individuals so that early detection and treatment can be provided for those who test positive for the disease.

Use additional code to identify any family history of malignant neoplasm (Z80.-)

Excludes1: encounter for diagnostic examination-code to sign or symptom

According to the ICD-10-CM Coding Guidelines, a screening code may be sequenced first if the reason for the visit is specifically for the screening exam. If a condition is discovered during the screening, the code for the condition may be assigned as a secondary diagnosis.

Be sure to report any personal history or family history of colon polyps, colorectal cancer, along with any personal history of a disease of the digestive system.

In the ICD-10-CM coding manual Index, look up Polyp, colon K63.5. Verified in the Tabular, K63.5 refers to Polyp of colon.


  • adenomatous polyp of colon (D12.6)
  • inflammatory polyp of colon (K51.4-)
  • polyposis of colon (D12.6)

Note: K63.5 is the default code for a colon polyp. If further specificity is provided, such as the location of the polyp, you would assign a different code.

Additional Information

These videos may help you better understand what happens during a colonoscopy and how polyps are removed. The snare technique is discussed.


The above post was written in 2018 but has been edited to reflect the 2019 coding guidelines.