RetiredPremera BluecrossPolicy CP.PP.239.v2.9

Modifier 23 - Unusual Anesthesia

Defines when the Plan recognizes and reimburses services appended with anesthesia modifier 23 for unusual anesthesia submitted on a professional claim across Premera and affiliated lines of business.

Policy Summary

PayerPremera Bluecross

PolicyModifier 23 - Unusual Anesthesia

Policy CodePolicy CP.PP.239.v2.9

Change TypeArchived / clarifications

Effective Date

Next Review Date

Key ActionProviders must sufficiently document the unusual circumstances that necessitated general or monitored anesthesia for a procedure that normally does not require it; documentation must be present in the member's medical record.

SourceLink

POLICY UPDATE CHANGES

Policy archived effective April 2, 2026.

Clarified that modifier 23 is not appropriate with moderate/conscious sedation codes (99151-99153, 99155-99157).

Clarified that the performing surgeon would append modifier 47 only to the main surgical procedure when they perform general or monitored anesthesia.

Multiple annual reviews with no clinical changes noted for several years.

00100-01999Primary CPT range referenced

99151-99153, 99155-99157Excluded CPT code groups (sedation)

AA,AD,QK,QS,QX,QY,QZPrimary anesthesia modifiers listed

Surgeon reporting modifier

Policy summary

This policy (CP.PP.239.v2.9) defines when the Plan recognizes and reimburses Modifier 23 (Unusual Anesthesia) when appended to general or monitored anesthesia procedure codes (CPT 00100-01999) on professional claims across Premera and affiliated lines of business. Coverage is dependent on documentation of the unusual circumstances in the member's medical record and on correct modifier sequencing — Modifier 23 must be appended after the primary anesthesia modifier (AA, AD, QK, QS, QX, QY, QZ). The policy also clarifies exclusions such as not appending Modifier 23 to moderate/conscious sedation codes (99151–99153, 99155–99157) and that a performing surgeon should append Modifier 47 to the main surgical procedure rather than billing a separate anesthesia code with Modifier 23. Status: RETIRED.

Policy metadata

Policy numberCP.PP.239.v2.9

SubjectModifier 23 - Unusual Anesthesia

StatusRETIRED

ScopeApplies across Premera Blue Cross and affiliated lines of business to professional claims for Modifier 23

Last review2026-03-12

Effective date

Key ActionProviders must document unusual circumstances in the member's medical record; append Modifier 23 after the primary anesthesia modifier (AA, AD, QK, QS, QX, QY, QZ).

Recognition and exclusions

Recognition of Modifier 23 - Unusual Anesthesia

Modifier 23 is recognized when ALL of the following are met:

ALL of the following

Service with Modifier 23: Service is appended with Modifier 23 (Unusual Anesthesia) on a professional claim.
Anesthesia CPT range: The anesthesia procedure is a general or monitored anesthesia procedure (CPT codes 00100-01999).
Procedure normally does not require anesthesia: The procedure normally does not require anesthesia or local anesthesia and must be performed under general or monitored anesthesia as a result of unusual circumstances.

Codes and modifiers

Allowed anesthesia CPT range for Modifier 23CPTCovered

00100-01999

General or monitored anesthesia procedure codes — Modifier 23 may be appended when criteria met

Primary anesthesia modifiers (must precede Modifier 23)Modifier

AA	Anesthesia services performed personally by anesthesiologist
AD	Medical supervision by a physician: more than four concurrent anesthesia procedures
QK	Medical direction of two, three, or four concurrent anesthesia procedures involving qualified individuals
QS	Monitored anesthesia care service
QX	CRNA service: CRNA with medical direction by physician
QY	Medical direction of one certified registered nurse anesthetist (CRNA) by an anesthesiologist
QZ	CRNA service: CRNA without medical direction by a physician

Not appropriate CPT codesCPTNot Covered

99151-99153	Moderate/conscious sedation — Modifier 23 not appropriate
99155-99157	Moderate/conscious sedation — Modifier 23 not appropriate

Surgeon anesthesia reportingModifier

47	Modifier 47 — Anesthesia by Surgeon; surgeon appends modifier 47 to main surgical procedure when they perform general or monitored anesthesia during the surgical procedure (do not bill separate anesthesia code)

Billing and documentation rules

Documentation Required

Document unusual circumstances

Providers must sufficiently document the unusual circumstances that necessitated general or monitored anesthesia for a procedure that normally does not require it; documentation must be present in the member's medical record.

00100-01999

Billing Rule

Order of modifiers when billing

When reporting Modifier 23, append it after the primary anesthesia modifier (AA, AD, QK, QS, QX, QY, QZ) on the professional claim.

Key terms

Definitions

Modifier 23Unusual Anesthesia — used when a procedure that normally does not require anesthesia must be performed under general or monitored anesthesia due to unusual circumstances; must be appended after the primary anesthesia modifier and only used with CPT codes 00100-01999.

Modifier 47Anesthesia by Surgeon — appended to the main surgical procedure when the surgeon provides general or monitored anesthesia during the surgical procedure; surgeon should not bill a separate anesthesia code with Modifier 23.

Policy changes & timeline

04/02/26revisedLatest

Policy archived effective April 2, 2026.|Version history notes the policy is archived effective 04/02/26.|notes: Version history entry: 'This policy is archived effective April 2, 2026.'

05/27/21added

Clarified that modifier 23 is not appropriate with moderate/conscious sedation codes (99151-99153, 99155-99157).|notes: Added in 05/27/21 version per version history.

04/06/23clarified

Policy Summary

PayerPremera Bluecross

PolicyModifier 23 - Unusual Anesthesia

Policy CodePolicy CP.PP.239.v2.9

Change TypeArchived / clarifications

Effective Date

Next Review Date

SourceLink

On This Page

Documentation required: Unusual circumstances are sufficiently documented in the member's medical records.

Documentation must be present in members' records; exact documentation elements not specified.

Modifier sequencing: Modifier 23 must be added after the primary anesthesia modifier that identifies whether service was personally performed, medically directed, or medically supervised (Modifiers AA, AD, QK, QS, QX, QY, QZ).

Modifier limited to anesthesia codes: Modifier 23 is used only with general or monitored anesthesia procedure codes (CPT 00100-01999).

Not Appropriate Uses / Exclusions

ALL of the following

Sedation codes excluded: Modifier 23 is NOT appropriate to be appended to moderate/conscious sedation codes (99151-99153, 99155-99157).
Surgeon performing anesthesia: If a surgeon provides general or monitored anesthesia during the surgical procedure they are performing, the surgeon should report services by adding modifier 47 (Anesthesia by Surgeon) to the main surgical procedure only and should NOT bill a separate anesthesia code (00100-01999) in addition to modifier 23.

Billing Rule

Surgeon performing anesthesia should use modifier 47

If the performing surgeon provides general or monitored anesthesia during their surgical procedure, they should append modifier 47 to the main surgical procedure and should not bill a separate anesthesia code (00100-01999) with modifier 23.

47
00100-01999
Do not bill a separate anesthesia code with modifier 23

Billing Rule

Do not append modifier 23 to sedation codes

Providers must not append modifier 23 to moderate/conscious sedation codes (99151-99153, 99155-99157).

99151-99153
99155-99157

Clarification that the performing surgeon would append modifier 47 to the main surgical procedure when they perform general or monitored anesthesia (initial wording indicated surgeon would append modifier 23).|notes: Minor clarification to the fourth paragraph indicating the performing surgeon would append modifier 23 to the main surgical procedure (04/06/23 entry).

05/19/23clarified

Correction: performing surgeon would NOT append modifier 23 to the main surgical procedure but continue to append modifier 47 only when they perform general or monitored anesthesia during the surgical procedure.|notes: CORRECTION entry on 05/19/23 clarifying surgeon should not append modifier 23 and should append modifier 47 only.

04/11/24administrative

Annual review; no clinical changes noted.|notes: Annual review entry (no changes).

03/07/25administrative

Annual review; no clinical changes noted.|notes: Annual review entry (no changes).