ICD-10 D66
Billable / Specific HCC v28: 46 MCCHereditary factor VIII deficiency
About ICD-10-CM D66
ICD-10-CM code D66 represents Hereditary factor VIII deficiency. This is a billable/specific code in the Blood and Blood-forming Organs chapter (block D66). The 2026 edition of ICD-10-CM D66 became effective on October 1, 2025.
Coding Tips for D66
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
D66 is a CMS-HCC v28 risk-adjustment code (category 46). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
D66 is designated MCC for MS-DRG grouping. On inpatient claims, this code can shift the DRG to the with-MCC variant when documented as a present-on-admission secondary diagnosis. Hospital CDI programs flag MCC opportunities during chart review. Failure to capture this code may leave 30 to 80 percent of the inpatient stay revenue unrealized.
Inclusion Terms / Approximate Synonyms
Clinical terms and conditions classified under D66. Per CMS ICD-10-CM Tabular 2026.
- Classical hemophilia
- Deficiency factor VIII (with functional defect)
- Hemophilia NOS
- Hemophilia A
Type 1 Excludes
Pure excludes, these codes can never be coded together with D66. The conditions are mutually exclusive (e.g., congenital vs acquired forms).
- factor VIII deficiency with vascular defect (D68.0-)
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Inpatient DRG Impact, MCC
codes Hereditary factor VIII deficiency. As a Major Complication/Comorbidity (MCC), this can shift the DRG assignment to a higher-weighted category, substantial reimbursement impact.
Medicare LCD Coverage for D66
Local Coverage Determinations (LCDs) from CMS MACs that list D66 as a covered diagnosis.
Showing top 10 of 33 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing D66.
2 Cigna
1 Medicare
CPT Codes Commonly Billed with D66
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- J7187 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7201 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7179 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7194 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7180 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7175 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7189 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7209 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7186 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
- J7182 CMS LCD: Billing and Coding: Guidance for Anti-Inhibitor Coagulant Complex (AICC) National Coverage Determination (NCD) 110.3 CMS LCD
Convert D66 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| D66 | 2860 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To D66
Other codes in section D65-D69 (Coagulation defects, purpura and other hemorrhagic conditions).
ICD-10 D66, Billing FAQ
Is ICD-10 code D66 billable? +
Yes, D66 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
What other names or terms map to D66? +
ICD-10 D66 includes: Classical hemophilia; Deficiency factor VIII (with functional defect); Hemophilia NOS, and 1 more clinical synonyms.
What codes are Type 1 Excludes for D66? +
Type 1 Excludes (never code together with D66): factor VIII deficiency with vascular defect (D68.0-)
Does D66 affect Medicare Advantage HCC risk adjustment? +
Yes. D66 maps to CMS-HCC v28 category 46. Capture this diagnosis annually for accurate Medicare Advantage risk score.
Is D66 a CC or MCC for inpatient DRG? +
Yes, this code is designated as MCC. Documenting as a secondary diagnosis on inpatient claims can shift the DRG to a higher-weighted category.
What CPT codes are commonly billed with D66? +
Procedures frequently paired with D66 include: J7187, J7201, J7179, J7194, J7180.
What ICD-9 codes does D66 map to? +
Per CMS GEMs, D66 maps to ICD-9 codes: 2860. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on June 1, 2026.
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