Coding for screening colonoscopies modifier can be challenging for coders and physicians. Particular areas of confusion include: When a screening colonoscopy is converted to a diagnostic/therapeutic colonoscopy & how should an incomplete colonoscopy be reported. Below is some guidance.

What is a screening colonoscopy?

It is a procedure performed on a patient who has no symptoms and involves inspection only. This is the examination of the entire colon from the rectum to cecum. The colonoscope is inserted in the anus and moved through the colon past the splenic flexure to visualize the lumen of rectum and colon. How does this differ from a diagnostic/therapeutic colonoscopy?

A colonoscopy with biopsy, polypectomy, or any removal of foreign body or any other intervention is not considered as diagnostic colonoscopy.

Diagnosis Coding

For professional claims & facility claims, the diagnosis code for a colonoscopy screening is Z12.11 (Encounter for screening for malignant neoplasm of colon.) This should be used as the first listed diagnosis code.

Assign secondary codes (if applicable) for a personal history or family history of colon polyps, colorectal cancer, and a personal history of a disease of the digestive system. If the patient has current inflammatory bowel disease such as Crohn’s disease or ulcerative colitis, a secondary code should be assigned that condition as well.

If a patient is high-risk for colon cancer that warrants colorectal cancer screening at an interval less than one every 10 years. The addition of these codes helps to cover medical necessity & justify the need for more frequent screenings.

CPT coding

CPT 45378 (Colonoscopy, flexible, proximal to splenic flexure, diagnostic) is used for most commercial payers for a screening colonoscopy. Medicare differs from commercial payors and uses one of two HCPCS codes. The HCPCS G-code selection is based on the patient’s level of risk. For average risk, G0121 is to be used & G0105 is used for high risk patients.

Modifier Usage

PT ~ colorectal cancer screening test; converted to diagnostic test or other procedure
33 ~ Preventative Services

Modifier PT & 33 are attached to a CPT code to inform the insurance company that the colonoscopy started as a screening, but ended up diagnostic/therapeutic. Modifier -PT is used for Medicare claims and modifier -33 is used for commercial payor claims.

Modifier 52 Reduced services
Modifier 53 Discontinued Procedure (not for hospital use)

Under certain circumstances, the physician may elect to terminate a surgical or diagnostic procedure.
Due to extenuating circumstances, it may be necessary to indicate that a surgical or diagnostic procedure was started but discontinued. This circumstance must be reported by adding CPT modifier 53 to the code reported by the physician for the discontinued procedure.
Coding Notes: This modifier is not used to report the elective cancellation of a procedure prior to the patient’s anesthesia induction and/or surgical preparation in the operating suite.
Hospitals may not submit CPT modifier 53. For outpatient hospital/ambulatory surgery center (ASC) report modifier 52.

Coding Scenario #1

Medicare Patient:
A 70-year-old patient presents to outpatient surgery area for a screening colonoscopy. The patient’s previous colonoscopy was at 59-years old, and was positive for one colon polyp. The patient has no history of colorectal cancer and no family history of polyps or colorectal cancer. The colonoscopy is performed in its entirety and was normal.

How should this be coded?

Z12.11 Encounter for screening for malignant neoplasm of colon
Z86.010 Personal history of colonic polyps
G0105 Colorectal cancer screening; colonoscopy on individual at high risk

Coding Scenario #2

Non-Medicare Patient:
A 55- year-old patient presents to the outpatient surgery area for a screening colonoscopy. She has not history of polys or colorectal cancer and has no family history of either. During her screening colonoscopy a polyp was found. The surgeon removes a polyp with a snare technique.

How should this be coded?

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


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