2027 ICD-10-CM Diagnosis Code B25.9Cytomegaloviral disease, unspecified
ICD-10-CM Codes›A00–B99›B25-B34›B25
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 6
- Not Chronic
B25.9 is a billable ICD-10-CM diagnosis code for cytomegaloviral disease, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 865 through 866, 974 through 976. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 19 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Viral infection.
For Medicare Advantage risk adjustment, B25.9 maps to CMS-HCC Category 6 (Opportunistic Infections) under the V28 model, adding a risk factor of about 0.381 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
B25.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Cytomegalovirus infection
- Cytomegalovirus infection of skin
- Cytomegalovirus viremia
- Disseminated cytomegalovirus infection
- Infection caused by Cytomegalovirus co-occurrent with human immunodeficiency virus infection
- Infection of central nervous system caused by Cytomegalovirus
- Myelitis caused by Cytomegalovirus
- Myelitis caused by herpes virus
- Ulcer of skin caused by Cytomegalovirus
- Ulcerative cytomegalovirus lesion
- Viremia
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to B25.9: its own notes plus those printed at B25 and Chapter 1. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- diseases generally recognized as communicable or transmissible
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- carrier or suspected carrier of infectious disease (Z22.-)
- certain localized infections - see body system-related chapters
- infectious and parasitic diseases complicating pregnancy, childbirth and the puerperium (O98.-)
- infectious and parasitic diseases specific to the perinatal period (P35-P39)
- influenza and other acute respiratory infections (J00-J22)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify resistance to antimicrobial drugs (Z16.-)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name B25.9, its category, or a range that includes it.
Applicable To 1
These notes mention B25.9.
- O98.5 Other viral diseases complicating pregnancy, childbirth and the puerperium
Excludes1 1
These codes carry an Excludes1 note naming B25.9: they are not reported together with it, unless the two conditions are unrelated.
- B34 Viral infection of unspecified sitecytomegaloviral disease NOS (B25.9)
Excludes2 2
These codes carry an Excludes2 note naming B25.9: its condition is not part of those codes, and both may be reported when the patient has both.
Use Additional Code 1
These codes say to use an additional code from the note, and B25.9 is one of the codes named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
inclusion B25.9
salivary gland B25.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Cytomegalovirus Infections
infection with cytomegalovirus, characterized by enlarged cells bearing intranuclear inclusions. infection may be in almost any organ, but the salivary glands are the most common site in children, as are the lungs in adults.
Patient EducationClinical
Cytomegalovirus Infections
Cytomegalovirus (CMV) is a virus found around the world. It is related to the viruses that cause chickenpox and infectious mononucleosis (mono). Between 50% and 80% of adults in the United States have had a CMV infection by age 40. Once CMV is in a person's body, it stays there for life.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert B25.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About B25.9Overview
What is the ICD-10 code for cytomegaloviral disease, unspecified?
The ICD-10-CM code for cytomegaloviral disease, unspecified is B25.9 (sometimes written as B259). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is B25.9 (Cytomegaloviral disease) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report cytomegaloviral disease, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does B25.9 group to?
When cytomegaloviral disease, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 974, 976, 975, 866, 865, with relative weights from 0.7879 to 3.0488 depending on complications. Higher weights mean higher Medicare reimbursement.
Is B25.9 a CC or MCC?
CMS lists B25.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 19 closely related codes in its exclusion list.
Can B25.9 be reported with P35.1?
Not as a rule. The Excludes1 note at B25, which applies to B25.9, lists "congenital cytomegalovirus infection (P35.1)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is B25.9?
B25.9 (cytomegaloviral disease, unspecified) maps to CMS-HCC Category 6 (Opportunistic Infections), commonly written as HCC 6, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 6 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 5.
Does B25.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, B25.9 adds a risk adjustment factor of about 0.381 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.381 to 0.833 depending on the payment segment). HCC 6 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 6 category page.
