CPT 00811: Anesthesia for Lower GI Endoscopy, and 00812 When It Is a Screening
00811 reports anesthesia for a lower intestinal endoscopy not otherwise specified, such as a diagnostic colonoscopy, with 4 base units. When the colonoscopy is a screening, the anesthesia practitioner reports 00812, and 00811 comes back only when the screening turns diagnostic.
Written by Salman Saeed, CEO and Co-Founder · Reviewed by a Certified Medical Coder · Last reviewed October 2026In short: 00811 has 4 base units. Medicare reports anesthesia for a screening colonoscopy as 00812 with 3 base units and no cost sharing, and as 00811 with modifier PT once the screening becomes diagnostic, with the deductible waived and coinsurance stepping down.
What Does CPT 00811 Report?
00811 reports anesthesia for a lower intestinal endoscopic procedure not otherwise specified, per the CMS short label. It carries 4 base units in the CMS base unit file, which CMS states are unchanged for CY 2026, and it has payment status J in RVU26D, so it is priced from units and not from RVUs.
Its closest relative is 00812, the CMS label for anesthesia for a screening colonoscopy, at 3 base units. The combined upper and lower code 00813 carries 5. For the upper scope see 00731. Like the other anesthesia codes, 00811 is not in the October 2026 practitioner MUE table.
When Is Anesthesia for a Colonoscopy 00811 and When Is It 00812?
Report 00812 when the colonoscopy is a screening and stays one, and 00811 with modifier PT when the screening becomes diagnostic. Claims Processing Manual Chapter 18, section 60.1.1, says this directly. The October 2026 HCPCS file defines PT as a colorectal cancer screening test converted to a diagnostic test or other procedure.
| Situation | Anesthesia code | Base units | Cost sharing (Chapter 18, section 60.1.1) |
|---|---|---|---|
| Screening colonoscopy that stays a screening | 00812 | 3 | Deductible and coinsurance waived |
| Screening that becomes diagnostic or therapeutic | 00811 with PT | 4 | Deductible waived; coinsurance reduced by date, below |
A colonoscopy that was diagnostic from the start has no screening to convert, so PT does not apply. The anesthesia claim therefore depends on the endoscopist's report: until someone confirms whether a biopsy or removal happened, the right code is unknown. The procedure side is on the 45378 page and 45385.
Time units are 30 / 15 = 2.0 in both cases. The conversion factor is the 2026 Manhattan locality value from the CMS ANES2026 file.
How Much Coinsurance Applies After a Screening Converts?
The patient share is shrinking on a fixed schedule. Section 122 of Division CC of the Consolidated Appropriations Act of 2021 amended section 1833(a) of the Social Security Act, and Chapter 18 applies it when PT is on at least one code on the claim for a screening G0104, G0105 or G0121 that became diagnostic or therapeutic. The deductible stays waived.
| Date of service | Coinsurance |
|---|---|
| Calendar years 2023 through 2026 | 15 percent |
| Calendar years 2027 through 2029 | 10 percent |
| January 1, 2030 and later | Waived |
Dates of service through December 31, 2026 carry the 15 percent step, and 2027 dates move to 10 percent. Moderate sedation by the endoscopist follows the same pattern: G0500 or 99153 carries modifier 33 with a screening and only PT after conversion. That is the endoscopist's claim, not the anesthesia line.
How Does 00811 Appear on the Claim?
On the CMS-1500, Item 24D holds 00811 with the payment modifier (AA, QK, QY, QX or QZ, covered on the 01402 page) and PT, and Item 24G holds the elapsed minutes. Chapter 26 says to convert hours into minutes. Item 24B holds the place of service.
Screening colonoscopy is an area where the endoscopist and the anesthesia practitioner bill on separate claims and must tell the same story. Match the screening or diagnostic status to G0121 or its high-risk twin on the endoscopy claim, since a mismatch leaves the anesthesia line with the wrong code.
What Goes in Item 24G and 24D for 00811?
For a lower intestinal endoscopy with anesthesia, the claim carries 00811 in Item 24D, the payment modifier and PT where the colonoscopy turned diagnostic, and elapsed minutes in Item 24G. Chapter 26 tells billers to convert hours into minutes, so enter the total, not hours and minutes separately. Item 24E must point to the same screening or diagnostic diagnosis the endoscopist reports.
RVU26D marks 00811 with status J, meaning an anesthesia service identified in the file with no RVUs or payment amounts, and the practitioner MUE table has no row for it. The minutes, not a unit cap, are the audit trail.
Example: A colonoscopy begins under anesthesia at 13:05 and ends at 13:41 on 10/19, 36 minutes. The line reads 00811, modifier AA, 36 in Item 24G, $410.00. If the polyp removal turns the case diagnostic, the endoscopy claim and this one should tell the same diagnosis story, or the payer may deny with CO-11.
Why Is 00811 Denied?
| Code | What X12 says | What usually causes it |
|---|---|---|
| CARC 4 | The procedure code is inconsistent with the modifier used | PT on 00811 when the endoscopy claim shows no screening, or no payment modifier |
| CARC 119 | Benefit maximum for this time period or occurrence has been reached | 00812 beside a screening denied for its interval; section 60.8 uses 119 for that |
| CARC 97 | The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated | 00811 beside 00813, or anesthesia billed by the endoscopist |
| CARC 18 with RARC M86 | Exact duplicate claim/service (group code OA); service denied because payment already made for same/similar procedure within set time frame | A screening repeated inside its interval |
If these denials keep coming back, our denial management team can work them. See also anesthesia billing.
Related Codes
- Physician Fee Schedule relative value files, RVU26D (October 2026) · CMS
- CY 2022 Anesthesia Base Units by CPT code (unchanged for CY 2026) · CMS
- Anesthesiologists Center: anesthesia base units and conversion factors · CMS
- Medicare NCCI Medically Unlikely Edits, practitioner services table, effective 10-01-2026 · CMS
- Medicare Claims Processing Manual, Chapter 12: Physicians/Nonphysician Practitioners · CMS
- Medicare Claims Processing Manual, Chapter 18: Preventive and Screening Services · CMS
- Medicare Claims Processing Manual, Chapter 26: Completing and Processing Form CMS-1500 Data Set · CMS
- HCPCS quarterly update, October 2026 alpha-numeric file · CMS
- Claim Adjustment Reason Codes · X12
- Remittance Advice Remark Codes · X12
We check every rule, code and deadline against the official source. See our editorial policy.
Common Questions
Straight answers from the team that does the work.
Ask a billing lead directly. A 20-minute call, Monday to Friday, 9am to 5pm Eastern.
01How do I bill anesthesia for colonoscopy?
Use 00812 when the colonoscopy is a screening and stays one, and 00811 with modifier PT when the screening becomes diagnostic or therapeutic. A colonoscopy that was diagnostic from the start uses 00811 without PT. Add a payment modifier such as AA or QK and report minutes in Item 24G.
02What does PT mean on anesthesia for colonoscopy?
PT is the HCPCS modifier for a colorectal cancer screening test converted to a diagnostic test or other procedure. Chapter 18 section 60.1.1 puts it on 00811 when a screening colonoscopy becomes diagnostic, so the deductible is waived and the reduced coinsurance schedule applies.
03How many base units does 00811 have?
Four. The CMS anesthesia base unit file lists 4 for 00811, 3 for the screening code 00812 and 5 for the combined upper and lower endoscopy code 00813. CMS states the base units are unchanged for CY 2026. Time units are added at 15 minutes each.
04What coinsurance applies to a converted colonoscopy in 2027?
Section 60.1.1 sets 15 percent for calendar years 2023 through 2026 and 10 percent for 2027 through 2029, with coinsurance waived on and after January 1, 2030. The deductible is waived throughout when PT is reported. The schedule keys off the date of service.
05Does modifier 33 go on 00812?
Chapter 18 does not put 33 on the anesthesia code. It names 33 for moderate sedation, G0500 or 99153, given with a screening colonoscopy. Anesthesia for a screening is reported with 00812, and after conversion with 00811 and PT, not 33.
Screening Colonoscopy Anesthesia Claims Denying?
We match the anesthesia code and PT to the endoscopy claim and the procedure report before it goes out.