CPT® Code 00812

Quick Reference

• Code definition: Reports anesthesia services furnished by a separate anesthesia provider (anesthesiologist or CRNA) during a colonoscopy that was scheduled and intended as a screening procedure, with the endoscope introduced distal to the duodenum.
• Key billing rule: Payment uses the anesthesia formula: (Base Units + Time Units + Physical Status Units) × Anesthesia Conversion Factor. Base units and the conversion factor update annually; verify both from the current CMS Physician Fee Schedule before billing [3].
• Modifier essentials: Every claim requires a provider-role modifier (AA, QZ, QK, QX, QY, or AD) and a physical status modifier (P1 through P6). Add QS when furnishing MAC sedation, as most MACs require it when propofol is used.
• Documentation must-have: Anesthesia start and stop times are required to calculate time units and drive payment. Start time is when preparation begins in the procedure room, not the pre-op evaluation time.
• Top confusion point: When a screening colonoscopy converts to therapeutic intraoperatively (polypectomy performed), the anesthesia code remains 00812. The anesthesia code is set by the intended procedure at induction, not by intraoperative findings. Only the endoscopist updates their code.
• Payer alert: Qualifying circumstance codes 99100, 99116, 99135, and 99140 carry Bundled Code status under Medicare and generate no separate payment. Commercial payers may recognize the additional ASA units these codes represent.
• Code history: Added January 1, 2018. Claims using deleted code 00810 for any date of service on or after 1/1/2018 will deny.

When to Use This Code

CPT 00812 applies when an anesthesiologist or CRNA furnishes anesthesia services for a colonoscopy that was scheduled and intended as a screening procedure at the time anesthesia was induced. The colonoscopy must involve an endoscope introduced distal to the duodenum.

Clinical indications align with preventive screening guidelines. Under Medicare NCD 210.3 [1], eligible patients are average-risk beneficiaries aged 45 and older (effective January 1, 2023 [2]) and high-risk beneficiaries with a personal or family history of colorectal cancer or adenomatous polyps. The anesthesia provider's service is separate from the endoscopic procedure: the endoscopist bills G0121 or G0105 while the anesthesia provider submits 00812 on an independent claim.

Scope boundaries: The code requires a lower GI approach with the endoscope introduced distal to the duodenum. If the endoscopist performs both upper and lower GI procedures in a single session, CPT 00813 applies instead. 00812 covers the complete anesthesia service: pre-anesthesia assessment, intraoperative monitoring and management, and post-anesthesia recovery oversight. Anesthetic drugs administered by the anesthesia provider are included and not separately billable on the professional or anesthesia claim; the facility may separately bill for drug supply.

Provider context: 00812 appears only on the anesthesia provider's claim, never on the endoscopist's claim. Type of service is 7 (Anesthesia). The global period concept does not apply (Global: XXX). APC status is Items and Services Packaged into APC Rates for facility claims.

Timed code billing: Unlike RVU-based surgical codes, anesthesia codes pay by the formula:

(Base Units + Time Units + Physical Status Units) × Anesthesia Conversion Factor

One time unit equals 15 minutes of anesthesia time. Round fractional units per MAC policy; some MACs accept actual minutes in Box 24G of the CMS-1500. The CY2025 anesthesia conversion factor ranges approximately $21.05 to $21.56 per unit depending on MAC locality; verify the current figure in the applicable MPFS Final Rule [3]. Base units for 00812 require direct verification against the current CMS Physician Fee Schedule Anesthesia Base Unit file, as values in secondary sources are not consistent [3].

Code Differentiation Table

The operative distinction between 00812 and 00811 is the intent of the colonoscopy at the time anesthesia begins. Verify the endoscopist's expected procedure code before selecting the anesthesia code: G0121 or G0105 on the endoscopist's claim confirms a screening encounter and supports 00812; a diagnostic CPT code such as 45378 without modifier 33 signals 00811.

flowchart TD
    A[Colonoscopy with separate anesthesia provider] --> B{Intended procedure\nat time of induction?}
    B --> C[Screening colonoscopy]
    B --> D[Diagnostic or therapeutic\ncolonoscopy]
    B --> E[Combined upper and\nlower GI endoscopy]
    C --> F[Use 00812]
    D --> G[Use 00811]
    E --> H[Use 00813]
    F --> I{Polyp found\nand removed?}
    I --> J[Yes: anesthesia code stays 00812\nEndoscopist adds modifier PT]
    I --> K[No: 00812 unchanged]

Billing & Modifier Rules

Provider-role modifiers are mandatory on every 00812 claim and determine the Medicare payment percentage [4]:

For medically directed cases using QK or QY, the supervising anesthesiologist must document all seven CMS medically directed steps [4]. Modifier pairs must be consistent across both providers' claims: QK on the anesthesiologist's claim requires QX on the CRNA's claim for the same case. Mismatched modifier pairs generate edits and can result in denial for one or both providers.

Physical status modifiers (P1 through P6) are appended alongside the provider-role modifier on every claim. Under Medicare, P3 adds 1 unit to the calculation, P4 adds 2 units, and P5 adds 3 units; P1 and P2 contribute zero additional units; P6 is not reportable for payment. Commercial payers and the ASA Relative Value Guide recognize physical status unit additions as well.

QS modifier: Most MACs require modifier QS when MAC sedation is furnished rather than general anesthesia. Requirements vary by jurisdiction; verify the applicable MAC's anesthesia billing article.

Add-on code: CPT 0887T (end-tidal control of inhaled anesthetic agents to assist anesthesia delivery) may be listed separately in addition to 00812 per CPT 2024 guidelines when applicable.

Qualifying circumstance codes 99100, 99116, 99135, and 99140 are listed separately per CPT instructions when applicable. Under Medicare, all four carry Bundled Code status and will not generate separate payment; the ASA assigns additional base units for these circumstances that some commercial payers may honor. Bill them per CPT guidance but do not expect Medicare reimbursement. Of these, 99100 (extreme age, over 70) is the most relevant to the Medicare colonoscopy population.

Bundling rules: 00812 and 00811 are mutually exclusive; both cannot appear on the same claim for the same encounter. NCCI PTP edits do not typically bundle anesthesia codes against surgical codes billed by a different provider or tax ID, as the two claims are submitted separately [5]. Anesthetic drugs supplied and administered by the anesthesia provider are included in 00812 and are not separately billable on the professional claim.

Documentation Essentials

The anesthesia record must contain the following elements to support 00812 payment and withstand audit [4]:

• Anesthesia start and stop times: Required to calculate time units and directly affect payment. Start time is when the anesthesia provider begins preparation in the procedure room, not the pre-op evaluation time.
• Physical status classification (P1 through P6): Must be assigned and documented by the anesthesia provider.
• Procedure name: Must reflect the intended screening colonoscopy. The record must not describe a diagnostic or therapeutic procedure intent.
• Provider identity and credentials: Name and licensure of the performing provider; if medically directed, documentation of all seven CMS medically directed steps is required.
• Anesthetic technique: MAC sedation, general anesthesia, or regional technique, as applicable.
• Pre-anesthesia evaluation: History, airway assessment, planned anesthetic approach, and informed consent.
• Post-anesthesia note: Patient condition on release from anesthesia care.

Medical necessity for separate anesthesia: When an anesthesia provider furnishes MAC sedation for a screening colonoscopy rather than the endoscopist administering moderate sedation, the record must document patient-specific clinical justification. OIG Report OEI-02-13-00110 [6] identified widespread claims for anesthesia during GI endoscopy without adequate medical necessity documentation, flagging it as a significant compliance risk. Acceptable patient-level factors include anxiety disorder, morbid obesity, history of failed moderate sedation, complex anatomy, and elevated ASA physical status (P3 or higher).

Audit red flag: Routine billing of 00812 for all colonoscopy patients at an endoscopy center without patient-level medical necessity documentation is a documented OIG audit trigger [6]. Uniform MAC sedation for all patients, absent clinical differentiation, has been associated with patterns of potential overpayment.

Medicare, Commercial & Medicaid Payer Rules

Medicare

Coverage for screening colonoscopy anesthesia derives from NCD 210.3 [1] and the general MPFS anesthesia payment rules in Chapter 12 of the CMS Claims Processing Manual [4]. No standalone NCD or LCD specifically covers 00812; coverage is contingent on the endoscopist's claim being covered.

Frequency limits determine 00812 eligibility:

• Average-risk (paired with G0121): once every 10 years, starting at age 45 as of January 1, 2023 [2]
• High-risk (paired with G0105): once every 2 years when personal or family history criteria are met

If the endoscopist's claim denies due to frequency limits or coverage criteria, the anesthesia claim will also deny. The anesthesia provider's reimbursement depends on the covered status of the underlying colonoscopy claim.

Medicare cost-sharing for anesthesia: Standard Medicare Part B cost-sharing generally applies to anesthesia services even when the colonoscopy itself may carry different cost-sharing rules as a preventive service. Verify current cost-sharing rules for anesthesia on preventive procedures at the applicable MAC.

MUE: Medicare does not apply a numeric MUE to anesthesia codes in the standard sense; MUE is listed as not applicable for 00812. Verify current status quarterly via CMS NCCI tools [5].

Commercial Payers

Under ACA Section 2713 (45 CFR §147.130) [7], non-grandfathered group health plans must cover USPSTF Grade A and B services without patient cost-sharing. CMS guidance confirms that anesthesia integral to a covered preventive colonoscopy must also be covered without cost-sharing.

CAA 2023 polyp loophole closure: For plan years beginning on or after January 1, 2023, the Consolidated Appropriations Act 2023 Section 102 requires ACA-regulated plans to waive cost-sharing for the entire colonoscopy encounter, including anesthesia, when a screening colonoscopy results in polypectomy [8]. This provision applies to fully insured employer plans and ACA marketplace plans; it does not apply to Medicare FFS.

Braidwood litigation: Ongoing federal litigation (Braidwood Management v. Becerra) has created enforcement uncertainty for self-insured ERISA plan sponsors in certain jurisdictions regarding ACA Section 2713 preventive service mandates [8]. Monitor for final resolution and verify plan-specific obligations with benefits counsel before advising patients on cost-sharing expectations.

Common Denials & Prevention

Deleted code submitted Submitting CPT 00810 for any date of service on or after January 1, 2018 results in automatic denial. The code was deleted effective December 31, 2017, and replaced by 00811, 00812, and 00813. Resubmit with the correct code and confirm the charge master was updated for the 2018 change.

Wrong lower GI anesthesia code selected Using 00811 for a screening colonoscopy, or using 00812 for a diagnostic colonoscopy, can trigger edits and affect patient cost-sharing calculations. Prevention: build a crosswalk in the billing workflow that maps the endoscopist's submitted code (G0121, G0105, or 45378 with modifier 33) to the correct anesthesia code before the claim is finalized.

Anesthesia claim denied when colonoscopy claim denies If the endoscopist's claim denies due to a frequency limit (colonoscopy performed before the eligible interval), the anesthesia claim will also deny. Prevention: verify colonoscopy eligibility against frequency limits under NCD 210.3 [1] when the procedure is scheduled. Confirm the patient meets age and frequency criteria before the date of service.

Missing or inconsistent modifier combination Omitting the provider-role modifier causes claim rejection. Billing QK on the anesthesiologist's claim without a corresponding QX on the CRNA's claim for the same case generates edits. Prevention: implement modifier pairing checks for all medically directed cases and verify that both providers' claims carry consistent modifier combinations before submission.

Insufficient medical necessity documentation for MAC sedation OIG audits have identified claims where anesthesia was billed for colonoscopy without patient-specific justification for why endoscopist-administered moderate sedation was insufficient [6]. Prevention: ensure the pre-anesthesia evaluation documents the specific clinical factors (anxiety, elevated BMI, prior anesthesia complications, ASA P3 or higher) that make separate anesthesia provider involvement clinically necessary.

Coding Scenarios

Scenario 1: A 62-year-old Medicare beneficiary with no colorectal cancer risk factors undergoes a first-time screening colonoscopy at an ambulatory surgery center. The anesthesiologist personally performs propofol MAC sedation for 30 minutes. No polyps are found.

Correct coding: 00812 with AA, QS, P1 (anesthesiologist's claim); endoscopist bills G0121.

Why: The average-risk screening paired with G0121 establishes 00812 as the correct anesthesia code. AA reflects personal performance; QS reports MAC sedation. P1 contributes zero additional units. Time units = 30 divided by 15 = 2 units.

Scenario 2: A 55-year-old Medicare beneficiary with a family history of colorectal cancer undergoes high-risk screening colonoscopy. An independent CRNA administers propofol MAC for 45 minutes. A 1.2 cm polyp is found and removed by snare technique.

Correct coding: CRNA bills 00812 with QZ, QS, P2; endoscopist bills 45385 with modifier PT.

Why: The colonoscopy was scheduled and induced as a screening procedure; the anesthesia code is determined by intent at induction, not by intraoperative findings. 00812 remains correct even after polypectomy. Modifier PT appears only on the endoscopist's claim to signal the conversion to Medicare; it is not added to the anesthesia claim.

Scenario 3: A 74-year-old Medicare patient with mild hypertension (P2) undergoes average-risk screening colonoscopy. An anesthesiologist medically directs one CRNA. Anesthesia time is 20 minutes.

Correct coding: Anesthesiologist bills 00812 with QY, QS, P2; CRNA bills 00812 with QX, QS, P2. Both bill at 50% of allowed. The anesthesiologist may also list 99100 per CPT instructions (patient over age 70), but should not expect separate Medicare payment for the qualifying circumstance code.

Why: Medical direction of one CRNA requires QY on the anesthesiologist's claim and QX on the CRNA's claim. Modifier pair consistency is required across both claims. Time units = 20 divided by 15 = 1.33; round per MAC policy. P2 contributes zero additional units under Medicare.

Scenario 4: A 47-year-old patient on a fully insured employer plan with a plan year beginning January 2, 2024, undergoes screening colonoscopy. A polyp is removed. The anesthesiologist personally performs MAC sedation.

Correct coding: Anesthesiologist bills 00812 with AA, QS, P1; endoscopist bills 45385 per applicable plan policy.

Why: Under CAA 2023 Section 102 for plan years beginning on or after January 1, 2023 [8], ACA-regulated plans must waive cost-sharing for the entire screening colonoscopy encounter, including anesthesia, when a screening converts to therapeutic. The anesthesia code does not change (00812 is correct based on screening intent at induction); however, the plan cannot apply cost-sharing to the anesthesia service. Confirm the plan is ACA-regulated before advising the patient.

Related Codes

• 00811 — Anesthesia, lower intestinal endoscopy, not otherwise specified; sibling code for diagnostic or therapeutic colonoscopy
• 00813 — Anesthesia, combined upper and lower GI endoscopy; use when both segments are scoped in one anesthesia encounter
• G0121 — Colorectal cancer screening, colonoscopy on average-risk patient; endoscopist's claim code paired with 00812
• G0105 — Colorectal cancer screening, colonoscopy on high-risk patient; endoscopist's claim code paired with 00812
• 45378 — Colonoscopy, flexible, diagnostic; endoscopist's code for diagnostic colonoscopy (paired with 00811, or with modifier 33 for commercial preventive claims)
• 45385 — Colonoscopy with snare polypectomy; endoscopist's code when screening converts to therapeutic (use with modifier PT on Medicare claims; anesthesia code remains 00812)
• 99100 — Anesthesia for patient of extreme age (under 1 year or over 70); qualifying circumstance add-on applicable to 00812; bundled under Medicare
• 0887T — End-tidal control of inhaled anesthetic agents; CPT 2024 add-on code to 00812 when applicable

Sources

1. CMS NCD 210.3 — Colorectal Cancer Screening — CMS Medicare Coverage Database — Medicare coverage criteria and frequency limits for screening colonoscopy
2. CMS MLN Matters MM12737 — Colorectal Cancer Screening Age Reduction — CMS, 2022 — Medicare screening colonoscopy eligibility age lowered to 45
3. CMS Physician Fee Schedule Search — CMS (annual updates) — Anesthesia base units and conversion factors; verify current year values
4. CMS Medicare Claims Processing Manual, Chapter 12 — CMS (ongoing; last revised 2024) — Anesthesia billing formula, modifier usage, time reporting, medically directed case rules
5. CMS NCCI Tools (PTP and MUE) — CMS (quarterly updates) — Current MUE values and PTP edit pairs
6. HHS OIG Report OEI-02-13-00110 — Anesthesia During Gastrointestinal Endoscopy — HHS OIG, 2015 — Medical necessity documentation issues and compliance risk for anesthesia during GI endoscopy
7. eCFR 45 CFR §147.130 — Coverage of Preventive Health Services — HHS/CMS — ACA Section 2713 preventive service cost-sharing mandate
8. Federal Register 88 FR 61352 — CAA 2023 Section 102 Implementation — HHS/CMS/DOL/Treasury, September 6, 2023 — Polyp loophole closure for ACA-regulated commercial plans