2027 ICD-10-CM Diagnosis Code J18.9Pneumonia, unspecified organism
ICD-10-CM Codes›J00–J99›J09-J18›J18
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Not Chronic
J18.9 is a billable ICD-10-CM diagnosis code for pneumonia, unspecified organism. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 193 through 195, 791, 793, 974 through 976. 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 129 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Pneumonia (except that caused by tuberculosis).
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acute erosive gastritis
- Acute gastroenteritis
- Acute pneumonia
- Acute ulcerative gastroenteritis complicating pneumonia
- Atypical pneumonia
- Bilateral pneumonia
- Chronic pneumonia
- Community acquired pneumonia
- Disorder of respiratory system co-occurrent with human immunodeficiency virus infection
- Erosive gastritis
- Foreign body pneumonia
- Hemorrhagic pneumonia
- Hospital acquired pneumonia
- Infectious disease of lung
- Obliterative bronchiolitis due to infectious disease
- Organized pneumonia
- Organizing pneumonia following infectious disease of lung
- Ornithosis
- Ornithosis with pneumonia
- Pleural effusion associated with pulmonary infection
- Pneumonia
- Pneumonia caused by Chlamydiaceae
- Pneumonia with AIDS
- Pneumonitis
- Pneumonitis due to foreign body
- Postoperative lower respiratory tract infection
- Postoperative pneumonia
- Recurrent bronchopulmonary infection
- Recurrent infection of upper and lower respiratory tract
- Recurrent lower respiratory tract infection
- Recurrent pneumonia
- Recurrent sinopulmonary infection
- Recurrent upper respiratory tract infection
- Respiratory disorder with AIDS
- Secondary organizing pneumonia
- Unresolved pneumonia
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to J18.9: its own notes plus those printed at J18, block J09-J18, and Chapter 10. A note printed at a category, block or chapter applies to every code under it.
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.
- abscess of lung with pneumonia (J85.1)
- aspiration pneumonia due to anesthesia during labor and delivery (O74.0)
- aspiration pneumonia due to anesthesia during pregnancy (O29)
- aspiration pneumonia due to anesthesia during puerperium (O89.0)
- aspiration pneumonia due to solids and liquids (J69.-)
- aspiration pneumonia NOS (J69.0)
- lipid pneumonia (J69.1)
- pneumonitis due to external agents (J67-J70)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- smoke inhalation (T59.81-)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Code First
The underlying condition named in the note is sequenced before this code.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code, if applicable, to identify resistance to antimicrobial drugs (Z16.-)
Code Also
A second code may be needed to fully describe the condition; the note gives no sequencing direction.
Notes
General instructions on how these codes are used.
- When a respiratory condition is described as occurring in more than one site and is not specifically indexed, it should be classified to the lower anatomic site (e.g. tracheobronchitis to bronchitis in J40).
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name J18.9, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming J18.9: they are not reported together with it, unless the two conditions are unrelated.
- J16 Pneumonia due to other infectious organisms, not elsewhere classifiedpneumonia NOS (J18.9)
Use Additional Code 1
These codes say to use an additional code from the note, and J18.9 is one of the codes named.
- J95.89 Other postprocedural complications and disorders of respiratory system, not elsewhere classified
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Infection, infected, infective (opportunistic) B99.9
lung See Also: Pneumonia; J18.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Pneumonia
infection of the lung often accompanied by inflammation.
Patient EducationClinical
Pneumonia
Pneumonia is an infection in one or both of your lungs. It causes the air sacs of your lungs to fill up with fluid or pus. Pneumonia can range from mild to severe, depending on what caused it, your age, and your overall health.
The full article covers:
- What is pneumonia?
- What causes pneumonia?
- Who is more likely to develop pneumonia?
- What are the symptoms of pneumonia?
- What other problems can pneumonia cause?
- How is pneumonia diagnosed?
- What are the treatments for pneumonia?
- Can pneumonia be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert J18.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About J18.9Overview
What is the ICD-10 code for pneumonia, unspecified organism?
The ICD-10-CM code for pneumonia, unspecified organism is J18.9 (sometimes written as J189). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is J18.9 (Pneumonia, unspecified organism) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report pneumonia, unspecified organism on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does J18.9 group to?
When pneumonia, unspecified organism is the principal diagnosis on an inpatient stay, it groups to MS-DRG 195, 793, 791, 193, 194, 974, 976, 975, with relative weights from 0.6062 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is J18.9 a CC or MCC?
CMS lists J18.9 as an MCC (major complication or comorbidity) for FY 2027. 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 129 closely related codes in its exclusion list.
Can J18.9 be reported with P23.0?
Not as a rule. The Excludes1 note at J18, which applies to J18.9, lists "congenital pneumonia (P23.0)". 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).
