2026 ICD-10-CM Diagnosis Code P23.1Congenital pneumonia due to Chlamydia
ICD-10-CM Codes›P00–P96›P19-P29›P23
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
P23.1 is a billable ICD-10-CM diagnosis code for congenital pneumonia due to Chlamydia. 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 68 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections, Perinatal infections, and Respiratory perinatal condition.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Chlamydia pneumoniae infection
- Congenital bacterial pneumonia
- Congenital chlamydial pneumonia
- Congenital pneumonia
- Neonatal chlamydial infection
- Neonatal chlamydial pneumonia
- Neonatal pneumonia
- Pneumonia caused by Chlamydia pneumoniae
- Pneumonia caused by Chlamydiaceae
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Chlamydia Infections
Chlamydia is a common sexually transmitted infection (STI). It is caused by bacteria called Chlamydia trachomatis. Anyone can get chlamydia. It often doesn't cause symptoms, so people may not know that they have it. Antibiotics can cure it. But if it's not treated, chlamydia can cause serious health problems.
The full article covers:
- What is chlamydia?
- How is chlamydia spread?
- Who is more likely to get chlamydia?
- What are the symptoms of chlamydia?
- How is chlamydia diagnosed?
- Who should be tested for chlamydia?
- What other problems can chlamydia cause?
- What are the treatments for chlamydia?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert P23.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About P23.1Overview
What is the ICD-10 code for congenital pneumonia due to Chlamydia?
The ICD-10-CM code for congenital pneumonia due to Chlamydia is P23.1 (sometimes written as P231). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is P23.1 (Congenital pneumonia) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report congenital pneumonia due to Chlamydia on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does P23.1 group to?
When congenital pneumonia due to Chlamydia 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 P23.1 a CC or MCC?
CMS lists P23.1 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 68 closely related codes in its exclusion list.
What is the ICD-9 equivalent of P23.1?
Under the General Equivalence Mappings, congenital pneumonia due to Chlamydia converts to ICD-9-CM 770.0 (congenital pneumonia). The mapping is approximate, so confirm the match fits the documentation.
