2026 ICD-10-CM Diagnosis Code P35.9Congenital viral disease, unspecified
ICD-10-CM Codes›P00–P96›P35-P39›P35
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
P35.9 is a billable ICD-10-CM diagnosis code for congenital viral disease, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 190 closely related codes. Coders also document this condition as acquired neutropenia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Perinatal infections and Viral infection.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acquired neutropenia
- Acquired neutropenia in newborn
- Congenital viral disease
- Transient neonatal neutropenia
- Transient neonatal neutropenia due to congenital viral infection
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disease, diseased See Also: Syndrome;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Uncommon Infant and Newborn Problems
It can be scary when your baby is sick, especially when it is not an everyday problem like a cold or a fever. You may not know whether the problem is serious or how to treat it. If you have concerns about your baby's health, call your health care provider right away.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert P35.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About P35.9Overview
What is the ICD-10 code for congenital viral disease, unspecified?
The ICD-10-CM code for congenital viral disease, unspecified is P35.9 (sometimes written as P359). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is P35.9 (Congenital viral diseases) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report congenital viral disease, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does P35.9 group to?
When congenital viral disease, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 791, 793, with relative weights from 4.0590 to 4.1696 depending on complications. Higher weights mean higher Medicare reimbursement.
Is P35.9 a CC or MCC?
CMS lists P35.9 as an MCC (major complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 190 closely related codes in its exclusion list.
What is the ICD-9 equivalent of P35.9?
Under the General Equivalence Mappings, congenital viral disease, unspecified converts to ICD-9-CM 771.2 (congenital infec NEC). The mapping is approximate, so confirm the match fits the documentation.
