CPT 45378: Diagnostic Colonoscopy
CPT 45378 reports a diagnostic colonoscopy, examination of the entire colon to the cecum, with or without brushing or washing but without biopsy or intervention. In 2026 Medicare pays about $378.10 non-facility and $164.67 facility, with a 000-day global period.
- Code type
- Surgical - diagnostic colonoscopy
- 2026 non-facility
- $378.10
- 2026 facility
- $164.67
- Global period
- 000 days
What is CPT 45378 used for?
CPT 45378 reports a diagnostic colonoscopy, a complete flexible endoscopic examination of the colon from the rectum to the cecum, and possibly the terminal ileum, with or without collection of specimens by brushing or washing. It is the base colonoscopy code, used when no biopsy, polypectomy, or other intervention is performed.
If any tissue is removed, you move to a therapeutic colonoscopy code such as 45380 for biopsy or 45385 for snare polypectomy. 45378 is the diagnostic-only starting point of the colonoscopy family.
How much does 45378 pay in 2026?
Under the 2026 Medicare fee schedule, 45378 allows about $378.10 non-facility and $164.67 facility for the professional service.
| Setting | 2026 Medicare allowed |
|---|---|
| Non-facility | ~$378.10 |
| Facility (ASC/hospital) | ~$164.67 |
Example: a gastroenterologist scopes a patient with rectal bleeding to the cecum with no biopsy taken. You bill 45378 at about $164.67 in the facility for the professional fee. Check your locality figure with the Medicare fee calculator.
How does screening change the code?
The single biggest colonoscopy billing decision is screening versus diagnostic, and for Medicare it changes the code entirely:
- Medicare screening, average risk: G0121.
- Medicare screening, high risk: G0105.
- Diagnostic (symptoms or findings): 45378.
- Non-Medicare screening: 45378 with a screening diagnosis.
When do modifiers 33 and PT apply?
When a screening colonoscopy is preventive and cost-sharing should be waived, commercial and Medicaid claims use modifier 33. For Medicare, when a screening exam converts to diagnostic or therapeutic during the procedure, append modifier PT to the CPT code; PT waives the Part B deductible. If a distinct second procedure is performed at a separate site, modifier 59 may separate it under the NCCI edits. With a 000 global period, no post-op days are bundled. When a biopsy is taken during upper endoscopy instead, see 43239. Confirm medical necessity on every diagnostic claim.
Frequently asked questions
In 2026 the national non-facility allowed amount is about $378.10, and the facility rate is about $164.67. Most colonoscopies are done in a facility, so the surgeon typically receives the professional fee. Medicare pays 80 percent after the deductible, though screening rules can waive cost-sharing.
For Medicare, a screening colonoscopy on an average-risk patient is G0121, and on a high-risk patient it is G0105. Report 45378 when the exam is diagnostic, meaning symptoms or findings prompted it, or for screening in non-Medicare patients using the appropriate screening diagnosis.
Modifier 33 marks a preventive service for commercial and Medicaid payers. Modifier PT is the Medicare modifier used when a screening colonoscopy converts to a diagnostic or therapeutic procedure; PT waives the Part B deductible but not, in 2026, the coinsurance. Use PT for Medicare and 33 for commercial.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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