CPT® Code 00813

Quick Reference

• Code definition: Reports anesthesia (general, regional, or monitored anesthesia care) administered during a single session in which endoscopes are introduced both proximal to the duodenum (upper GI) and distal to the duodenum (lower GI), such as a simultaneous EGD and colonoscopy.
• Key billing rule: Do not separately bill 00811 and 00812 for a combined session. CPT guidelines require 00813 when the endoscope is introduced both proximal to and distal to the duodenum in the same encounter [2].
• Modifier essentials: A physical status modifier (P1 through P6) and an anesthesia delivery modifier (AA, QZ, QX, QK, or QY) are required on every claim. MAC encounters also require QS.
• Documentation must-have: The anesthesia record must confirm both upper and lower scope insertions occurred, with total anesthesia time, anesthesia type, and physical status documented.
• Top confusion point: Selecting 00811 or 00812 when both upper and lower GI procedures were performed in the same session is unbundling. CPT guidelines are unambiguous: one scope session spanning both anatomical regions requires 00813 [2].
• Code history: Added January 1, 2018, replacing deleted code 00810. Claims and legacy crosswalk references for 00810 should route to 00813.
• Add-on availability: 0887T (end-tidal control of inhaled anesthetic agents) may be reported in addition to 00813 when applicable; it requires a primary anesthesia code from the 00100 to 01999 range [2].

When to Use This Code

00813 applies when a single anesthesia encounter covers both an upper GI endoscopic procedure (endoscope introduced proximal to the duodenum, such as an EGD or esophagoscopy) and a lower GI endoscopic procedure (endoscope introduced distal to the duodenum, such as a colonoscopy or flexible sigmoidoscopy) performed during the same operative session.

The defining criterion is dual introduction: the GI tract was examined both above and below the duodenum during the same encounter. Common combined sessions include EGD plus colonoscopy (the most frequent scenario), EGD plus flexible sigmoidoscopy, and upper GI endoscopy with biopsy combined with colonoscopy with polypectomy.

Scope boundaries: If only an upper GI procedure was performed (EGD alone), use 00811. If only a lower GI procedure was performed (colonoscopy alone), use 00812. If the procedure is specifically an ERCP without a concurrent lower GI scope, use 00732. The CPT codebook cross-reference under 00732 states that for combined upper and lower GI endoscopic procedures, 00813 is the correct code [2].

Provider and setting context: This code is reported by the anesthesia provider (anesthesiologist or CRNA), not the gastroenterologist. Facility billing for outpatient hospital settings packages anesthesia into the APC payment; the professional anesthesia claim is submitted separately under the anesthesia fee schedule. GI endoscopy suites, ambulatory surgery centers, and hospital outpatient departments are all valid sites of service.

Anesthesia time units: Report time from induction through emergence. Medicare uses 15-minute increments; each insurer may specify its own unit definition. Anesthesia time is reported continuously across both the upper and lower procedures because 00813 covers the entire combined session; there is no separate time allocation per scope.

Code Differentiation Table

The critical distinction is procedural scope, not anatomical complexity or anesthesia type. If the gastroenterologist's operative note documents both an EGD and a colonoscopy in the same session, 00813 is the only correct choice. Billing 00811 and 00812 separately for the same encounter constitutes unbundling and triggers NCCI edit exposure [4].

flowchart TD
    A[Single anesthesia session for GI endoscopy] --> B{Was endoscope introduced\nproximal to duodenum?}
    B -- No --> C[Lower GI only\n→ 00812]
    B -- Yes --> D{Was endoscope also introduced\ndistal to duodenum?}
    D -- No --> E{Is procedure\nspecifically ERCP?}
    E -- Yes --> F[ERCP\n→ 00732]
    E -- No --> G[Upper GI only\n→ 00811]
    D -- Yes --> H[Combined upper + lower GI\n→ 00813]

Billing & Modifier Rules

Anesthesia delivery modifiers (required): Every 00813 claim requires exactly one delivery modifier identifying who provided anesthesia and the supervision arrangement [3]:

• AA: Anesthesiologist personally performed (12.01% of claims)
• QZ: CRNA performing without anesthesiologist medical direction (19.00% of claims)
• QX: CRNA performing with anesthesiologist medical direction (14.32% of claims)
• QK: Medical direction of two to four concurrent anesthesia procedures by an anesthesiologist (10.04% of claims)
• QY: Anesthesiologist medically directing one CRNA (1.77% of claims)

MAC modifier: QS is appended when the clinical decision was made to use monitored anesthesia care rather than general or regional anesthesia. At 30.93% of claims, QS is the most frequently used modifier on this code, reflecting MAC as the dominant anesthesia modality for GI endoscopy [1]. QS is appended in addition to the delivery modifier, not in place of it.

Physical status modifiers (required): One physical status modifier is appended to every claim. Medicare does not separately reimburse physical status units, but many commercial payers add units per ASA convention (typically +1 for P2, +2 for P3, +3 for P4). Accurate assignment affects payment under commercial contracts [5].

Add-on code 0887T: Report 0887T in addition to 00813 when end-tidal control of inhaled anesthetic agents and oxygen is used to assist anesthesia delivery. The CPT codebook instruction states 0887T must be used in conjunction with a primary code from the 00100 to 01999 range; it cannot be reported alone [2].

High-risk MAC modifiers: G9 applies when MAC is provided to a patient with a history of severe cardiopulmonary conditions. G8 applies for MAC during deep, complex, or markedly invasive procedures. Both are appended when applicable to distinguish the clinical complexity of MAC from routine sedation monitoring.

Discontinued procedure modifiers: If the combined procedure is terminated after anesthesia induction, append modifier 53. For outpatient hospital and ASC settings, use modifier 74 after anesthesia administration has begun.

NCCI bundles: NCCI edits associate modifier 59 and its X-modifier variants (XE, XS, XU) with 00813 for use when a service is documented as distinct. The primary bundling risk for this code is not within 00813 itself but in the upstream coding decision: billing 00811 plus 00812 for the same session creates an NCCI edit that cannot be bypassed with modifier 59 because they are not distinct services; they are one combined session [4].

Documentation Essentials

The anesthesia record must establish that both upper and lower GI procedures were performed in the same encounter, as this is the defining criterion for 00813 over 00811 or 00812.

Required elements:

• Documentation of both the upper GI procedure (EGD, esophagoscopy, gastroscopy) and the lower GI procedure (colonoscopy, sigmoidoscopy) with scope type and anatomical extent described
• Anesthesia start time (patient entry to anesthesia care) and stop time (patient released from anesthesia care)
• Type of anesthesia administered (general, MAC, regional) with clinical rationale for MAC if QS is billed
• Physical status assignment with supporting clinical rationale for P3 or P4 classifications
• Provider signature and credentials confirming the delivery role (drives AA vs QX vs QZ modifier selection)
• For medical direction claims (QK, QY), documentation of all seven required CMS medical direction elements [3]

Audit red flags:

• Absence of lower GI procedure documentation when 00813 is billed; auditors will downcode to 00811 if only an EGD is documented
• Anesthesia record showing time gaps between procedures without clinical explanation; combined sessions should document continuous monitoring
• QS modifier without a MAC decision documented in the pre-anesthesia evaluation or anesthesia record
• Physical status P3 or P4 with no supporting comorbidity documentation; elevated ASA classification is a frequent audit target in GI anesthesia claims

Medicare, Commercial & Medicaid Payer Rules

Medicare:

Medicare pays anesthesia services under the anesthesia fee schedule, separate from the MPFS. Payment uses the formula: (Base Units + Time Units) × Anesthesia Conversion Factor, adjusted geographically [3]. The APC status indicator for 00813 is "Items and Services Packaged into APC Rates," meaning facility anesthesia is packaged into the outpatient APC payment. The anesthesia provider's professional claim bills separately to the Part B MAC.

Medicare does not reimburse physical status modifier units; P modifiers are required for claim completion but do not increase payment under the Medicare anesthesia fee schedule. Medical direction (QK, QY) requires the anesthesiologist to meet all seven CMS medical direction criteria; deficiencies downgrade the claim to the CRNA rate [3].

For Medicare beneficiaries undergoing colorectal cancer screening colonoscopy combined with an upper GI procedure, modifier PT may apply to the surgical procedure code when the colonoscopy converts from screening to diagnostic or therapeutic. Modifier PT affects the patient's cost-sharing, not the anesthesia code selection; it is appended by the gastroenterologist, not the anesthesia provider.

Commercial payers:

Commercial payers generally follow ASA Relative Value Guide base units multiplied by their contracted conversion factors [5]. Unlike Medicare, many commercial payers do reimburse physical status modifying units, so accurate P modifier assignment directly affects payment. Verify payer-specific policy on physical status unit reimbursement before assuming Medicare billing methodology applies.

Some commercial payers apply prior authorization requirements for elective GI anesthesia, particularly MAC, when medical necessity over moderate sedation is not documented. QS claims may be subject to post-payment review. Documentation supporting MAC should address patient-specific clinical factors: obstructive sleep apnea, obesity, GERD with aspiration risk, prior sedation failure, or significant anxiety precluding cooperation.

The CPT guidelines are explicit that moderate sedation codes (99151 to 99157) are not reported when anesthesia codes (00100 to 01999) are used [1]. Payers will deny 99151 to 99157 billed concurrently with 00813.

Common Denials & Prevention

Unbundling: 00811 and 00812 billed separately for combined session The root cause is a coding workflow that assigns anesthesia codes per procedure rather than per session. An NCCI edit will bundle these claims and pay only one. Prevention: implement a front-end edit that flags simultaneous 00811 and 00812 for the same date and provider, and replace with 00813 when both upper and lower procedures are documented.

Downcode to 00812: missing upper GI documentation Auditors downcode to 00812 when the claim shows 00813 but the operative note documents only a colonoscopy. Prevention: the anesthesia team should verify the procedure list at case start and confirm the EGD or upper scope was completed before coding 00813. If the upper GI procedure was cancelled intraoperatively, the code must be changed before claim submission.

Rejection: missing anesthesia delivery modifier Claims submitted without AA, QZ, QX, QK, or QY are rejected as incomplete at the claim-edit level. Prevention: configure the billing system to require one delivery modifier before claim release; this is a workflow control issue, not a coding judgment issue.

Denial: MAC without medical necessity documentation Payers deny QS claims when the patient record lacks clinical justification for anesthesia-level care instead of moderate sedation [3]. Prevention: the pre-anesthesia evaluation must document the specific factors supporting MAC (e.g., ASA P3 or P4 status, documented sleep apnea, prior sedation failure, procedural complexity). A generic note that "patient requested anesthesia" is insufficient for most commercial payers on appeal.

Denial: 0887T billed without valid primary anesthesia code 0887T cannot stand alone; it requires a primary code from the 00100 to 01999 range on the same claim. Prevention: configure the billing system to validate that a primary anesthesia code is present when 0887T is submitted.

Coding Scenarios

Scenario 1: A healthy 52-year-old male (ASA P1) presents for combined colorectal cancer screening colonoscopy and EGD to evaluate dyspepsia. An anesthesiologist personally administers MAC for both procedures; total anesthesia time is 45 minutes.

Correct coding: 00813 with AA, QS, P1

Why: Both upper and lower GI scopes were used in the same session, requiring 00813 rather than 00811 or 00812. AA confirms personal performance; QS designates MAC. Time units: 45 minutes equals 3 time units at 15-minute increments.

Scenario 2: A 67-year-old Medicare beneficiary with controlled hypertension and type 2 diabetes (ASA P2) undergoes EGD with biopsy and colonoscopy with polypectomy. A CRNA performs anesthesia without anesthesiologist medical direction. The colonoscopy began as a screening exam and converted to a therapeutic procedure upon polypectomy.

Correct coding: 00813 with QZ, QS, P2

Why: QZ designates CRNA service without medical direction. Modifier PT is appended by the gastroenterologist to the colonoscopy procedure code to reflect the screening-to-therapeutic conversion; it does not affect anesthesia code selection. P2 reflects mild systemic disease supported by the documented comorbidities.

Scenario 3: A coder receives an operative note for an ERCP with sphincterotomy. No colonoscopy or lower GI scope was performed. The operative note references "GI endoscopy" and the coder considers 00813.

Correct coding: 00732, not 00813

Why: ERCP is an upper GI procedure; the endoscope was not introduced distal to the duodenum. CPT instructs that 00732 is the correct code for ERCP. 00813 requires the endoscope to be introduced both proximal and distal to the duodenum; an ERCP alone does not meet that criterion [2].

Scenario 4: An anesthesiologist medically directs two concurrent MAC cases in adjacent suites: 00813 for a combined EGD plus colonoscopy and 00812 for a standalone colonoscopy. The patient for the combined case has severe COPD (ASA P3) and a documented history of cardiopulmonary disease. The physician documents all seven CMS medical direction elements.

Correct coding for the combined case: 00813 with QK, QS, P3, G9

Why: QK designates medical direction of two to four concurrent procedures. G9 is appropriate given the documented severe cardiopulmonary history requiring MAC. P3 is supported by the COPD documentation in the pre-anesthesia evaluation.

Related Codes

• 00811: Anesthesia for upper GI endoscopy, NOS; use when only upper GI scope is introduced
• 00812: Anesthesia for lower GI endoscopy, NOS; use when only lower GI scope is introduced
• 00732: Anesthesia for ERCP specifically; use when upper GI ERCP is performed without a concurrent lower GI procedure
• 0887T: End-tidal control of inhaled anesthetic agents; add-on to 00813 when applicable (2024 code)
• QS: MAC modifier; most frequently appended modifier on this code at 30.93% of claims
• AA: Anesthesiologist personally performed; required delivery modifier when applicable
• QZ: CRNA without medical direction; required delivery modifier when applicable

Sources

1. CPT Codebook Anesthesia Guidelines, American Medical Association — Official CPT guidelines governing anesthesia code reporting, physical status modifiers, MAC vs moderate sedation distinction, and VR procedural dissociation exclusions
2. CPT Code 00813 Codebook Cross-References, American Medical Association — Codebook references: 00810 deletion effective 2018-01-01; 00732 cross-reference directing combined upper and lower GI procedures to 00813; 0887T add-on code pairing instruction
3. CMS Medicare Claims Processing Manual, Chapter 12 — Anesthesia Services — Medical direction criteria (seven elements for QK/QY), anesthesia fee schedule formula (Base + Time units × conversion factor), MAC medical necessity standards
4. CMS NCCI Policy Manual — NCCI edit pairs applicable to anesthesia codes; modifier bypass requirements (59, XE, XS, XU)
5. ASA Relative Value Guide, American Society of Anesthesiologists — Base unit assignments for anesthesia CPT codes; physical status modifier unit values for commercial payer billing and ASA-method claim calculation