ICD-10 Code Y90.9: Presence of alcohol in blood, level not specified

Key Takeaways

ICD-10 Code Y90.9 describes presence of alcohol in blood, level not specified, and is billable for FY2026 (effective October 1, 2025).

Y90.9 is a secondary-only external cause code; it can never be sequenced as a principal diagnosis.

Use Y90.9 when alcohol is detected but no specific BAC mg/100ml range is documented; use Y90.0-Y90.8 when the level is recorded.

Practice management software like Pabau supports accurate secondary code sequencing directly within the clinical documentation workflow.

ICD-10 Code Y90.9, Presence of alcohol in blood, level not specified, is a billable, secondary-only external cause code used when a blood alcohol test confirms alcohol presence but no specific concentration is documented. Per CMS ICD-10-CM Official Guidelines, external cause codes in Chapter XX always supplement a principal diagnosis and can never be sequenced as primary.

This reference covers the full Y90 family, coding guidelines, primary diagnosis pairings, FY2026 validity, and the clinical documentation practices that determine whether Y90.9 or a specific Y90.x subcode is appropriate.

ICD-10 Code Y90.9: Definition and billable status

ICD-10 Code Y90.9 is a billable, specific ICD-10-CM code valid for FY2026 reimbursement. Its official description is “Presence of alcohol in blood, level not specified.” The code became effective October 1, 2025 under the 2026 edition of ICD-10-CM, and its description and billable status are unchanged from prior editions.

The WHO ICD-10 browser classifies the international version of this code under the same block (Y90-Y98: Supplementary factors related to causes of morbidity and mortality classified elsewhere). The American ICD-10-CM version used in US billing may carry minor structural differences from the international version, but the core description is consistent.

The Y90 category: All blood alcohol level subcodes

Category Y90 captures evidence of alcohol involvement determined by blood alcohol level (BAC). Ten subcodes cover the full range from unmeasurably low to very high concentrations, plus the unspecified option. Understanding the entire family is what determines whether Y90.9 or a more specific code applies to a given encounter.

The decision between Y90.9 and a specific subcode is entirely a documentation question. When the BAC result is recorded in the chart in a unit that maps to one of the eight ranges above, coders must use the matching specific code.

Y90.9 is only appropriate when alcohol presence is confirmed but no quantified BAC result is available in the record. Reviewing CDC/NCHS ICD-10-CM lookup tools confirms this distinction in the tabular list notes for category Y90.

How to use ICD-10 Code Y90.9 correctly: Coding guidelines

ICD-10 Code Y90.9 is an external cause code. Per CMS ICD-10-CM Official Guidelines, Section I.C.20, external cause codes in Chapter XX supplement a principal diagnosis. They are never the reason for the encounter on their own. Getting this sequencing right protects the claim from automatic denial at the edit level.

• Always secondary: Y90.9 must follow a principal diagnosis code. The principal code explains why the patient was seen; Y90.9 adds context about alcohol involvement confirmed by a blood test.
• Confirm alcohol detection in the record: The physician’s note must document that alcohol was detected in the blood, typically through a blood alcohol test or lab result referenced in the encounter documentation.
• Use Y90.9 only when BAC level is absent: If the lab result is present but the level is simply not recorded in the physician’s note, the coder should query the provider rather than default to Y90.9.
• Multiple external cause codes are permitted: A claim can carry Y90.9 alongside other Chapter XX codes (for example, a transport accident code) as long as sequencing follows Official Guidelines priority rules.
• Not for suspected alcohol use: Clinical suspicion alone does not support Y90.9. A blood alcohol test must be performed and a result documented, even if the concentration is not quantified.

Coders working in practices that handle substance-related encounters should also be familiar with X71.9XXS, another Chapter XX code where the same secondary-only sequencing rule applies.

Primary diagnoses commonly paired with Y90.9

Because Y90.9 requires a principal diagnosis, coders must identify the correct primary code first. The following conditions are the most common primary pairings in encounters where blood alcohol is documented without a specific level.

Practices managing substance use encounters sometimes see comorbid presentations where alcohol involvement appears alongside a chronic condition such as K73.8, requiring careful sequencing across multiple diagnosis codes.

Behavioral health encounters add another layer when alcohol involvement and a psychiatric diagnosis are documented together. In those cases, the psychiatric diagnosis typically holds priority as the principal code when it is the reason for the visit, with Y90.9 and any other external cause codes following in sequence. For practices with high volumes of behavioral health encounters, a mental health EMR with integrated code lookup reduces sequencing errors, and practices in psychiatry and dual-diagnosis settings can look to psychiatry EMR software built around the same coding workflows.

External cause codes and Chapter XX: Regulatory context

Chapter XX of ICD-10-CM (V00-Y99) is officially titled External Causes of Morbidity. These codes explain how an injury or condition happened, not what the condition is. They are supplementary by design, which is why Y90.9 can never stand alone as a principal diagnosis regardless of payer or setting.

• Regulatory basis: HIPAA mandates use of ICD-10-CM code sets for covered transactions in the US. Chapter XX codes are part of that mandated set and must follow CMS Official Guidelines when submitted on claims.
• Payer variation: While CMS guidelines are the foundational standard, individual payers may have local coverage determinations (LCDs) that affect how external cause codes are processed. Always confirm with the specific payer’s manual before assuming universal acceptance.
• Hospital outpatient vs. inpatient: External cause codes are used in both settings, but sequencing priority rules differ. In inpatient coding, the principal diagnosis is determined after study; in outpatient coding, it is the confirmed condition that drove the encounter. Y90.9 follows the same secondary placement in both contexts.
• Not required but recommended: CMS guidelines do not mandate external cause codes for all payers in all circumstances, but they add clinical specificity that supports medical necessity documentation and accurate data reporting.

Documentation-driven specificity isn’t unique to Y90.9. Codes like I74.5 follow the same principle: the more precise the chart notes, the more specific the code a coder can assign.

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Pabau lets your team attach secondary codes like Y90.9 directly within the clinical record, with built-in sequencing prompts that flag when a primary diagnosis is missing.

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Y90.9 crosswalk: ICD-9-CM and ICD-11 equivalents

Legacy system users and practices transitioning between classification systems sometimes need to map Y90.9 to its predecessors or successors. The crosswalk information below is for reference; always verify against AAPC’s ICD-10-CM tools and official CMS General Equivalence Mapping (GEM) files before using in a production billing environment.

The ICD-9-CM crosswalk for Y90.9 is approximate. ICD-9 code 790.3 (Excessive blood level of alcohol) did not carry the quantified BAC ranges introduced with ICD-10. Any mapping from ICD-9 to Y90.9 should be treated as a general equivalence, not a precise clinical match.

Always confirm with official CMS GEM files when using crosswalks for retroactive data analysis or legacy billing corrections.

2026 edition update: Is Y90.9 valid for FY2026?

Yes. ICD-10 Code Y90.9 is valid for FY2026. It became effective October 1, 2025, under the annual ICD-10-CM update cycle maintained by CMS and NCHS. No changes were made to the code’s description, billable status, or secondary-code-only designation in the FY2026 edition.

Practices can continue using Y90.9 on claims with dates of service on or after October 1, 2025 without any code substitution or transition adjustments.

Coders should verify the CMS ICD-10-CM annual update files each October 1 to confirm that no revisions have been applied to Y90.9 or its parent category Y90 in subsequent fiscal years. This is standard annual validation practice for any external cause code in active clinical use.

Billing and reimbursement considerations for ICD-10 Code Y90.9

External cause codes like Y90.9 do not trigger direct reimbursement on their own. Their function on a claim is to add specificity that supports the medical necessity of the primary diagnosis code. That said, missing or incorrectly sequenced external cause codes can trigger payer edits that delay or deny the entire claim.

• Missing primary diagnosis: Submitting Y90.9 without a principal diagnosis code will result in automatic rejection. Every claim line with Y90.9 must carry a valid primary code in the first diagnosis position.
• Payer LCD policies: Some payers require external cause codes on alcohol-related encounters for specific claim types (workers’ compensation, auto liability). Review the applicable LCD or payer manual to confirm requirements for your payer mix.
• Documentation must support the code: The clinical note must reference a blood alcohol test result. A general notation of “alcohol use” without a BAC test documented does not support any code in the Y90 family.
• Audit risk: Y90.9 on a claim where a specific BAC level appears in the lab results (even if not in the physician note) creates a documentation inconsistency that auditors flag. Use the most specific subcode supported by the complete encounter record.

Practices managing HIPAA-compliant medical billing workflows need external cause code sequencing built into their clinical documentation process, not added as a last step. Software that flags a missing secondary code within the clinical record reduces the manual audit burden on coding staff.

Documenting blood alcohol level in clinical notes

Reference sites explain what Y90.9 means, but they rarely explain what the physician needs to write in the chart for the coder to assign it correctly, or what documentation shifts the code from Y90.9 to a specific Y90.x subcode.

The following documentation decision guide gives clinicians and coders a shared framework for evaluating chart notes against the Y90 code family.

For practices that use structured clinical records, prompting physicians to document BAC results within the encounter note, not only in a separate lab tab, ensures coders have everything they need to assign the most specific Y90 subcode.

Digital intake forms that include fields for substance screening results can also carry this documentation through from triage to clinical note, so a lab-positive result reaches the coder in a form that supports a properly coded claim.

Practices concerned about maintaining complete, auditable records should review their protocols for protecting patient health records across all encounter documentation.

Conclusion

ICD-10 Code Y90.9 is specific, billable for FY2026, and useful. What makes it complicated is the documentation dependency: coders cannot assign it accurately without complete encounter records, and physicians often do not know exactly what detail determines whether Y90.9 or a specific Y90.x applies.

The chart documentation decision table above is the practical fix. Build it into coder training and physician feedback loops.

Pabau supports secondary code workflows by flagging a missing primary diagnosis within the clinical record before the coder finalizes the encounter, addressing the most common Y90.9 documentation error. To see how this fits into a complete clinical documentation and billing workflow, book a demo.

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