If you’ve ever stared at a chest X-ray report that says “multifocal opacities” and thought, “Okay… but what code do I use for this?” — you’re not alone.
Multifocal pneumonia can sound vague at first. It’s not a specific bug like pneumococcal pneumonia, and it’s not clearly tied to a single lobe like lobar pneumonia. It simply means there are multiple infected areas in the lungs, and depending on the documentation, it can fall under a few different ICD-10 codes.
And here’s where things get tricky: ICD-10 doesn’t have a code labeled ‘multifocal pneumonia’. That means your job is to translate the clinical picture into the right billing language — a core part of accurate medical coding.
At Cadence Collaborative, we help teams do exactly that every day. This guide breaks it down clearly so you can stop second-guessing and start coding with confidence.
What Is Multifocal Pneumonia
Multifocal pneumonia is a clinical description, not a diagnosis code. It means that more than one area of the lung is involved — often seen on imaging like chest X-rays or CT scans — and can appear in both lungs or in multiple lobes of the same lung.
But when it comes to ICD-10, you’ll need to assign a code that reflects:
- The cause or type of pneumonia, if known
- Whether it’s bacterial, viral, fungal, or unspecified
- Whether it’s in one lung or both (bilateral)
- Whether it’s associated with another condition (like COVID-19 or aspiration)
The phrase “multifocal” itself isn’t enough — ICD-10 wants specifics.
Which ICD-10 Codes to Use for Multifocal Pneumonia
There’s no single ICD-10 code labeled “multifocal pneumonia,” but that doesn’t mean you’re out of options. The right code depends on how well the provider has documented the cause and characteristics of the pneumonia.
Let’s walk through the most commonly used codes — and when to choose each one.
1. J18.9 – Pneumonia, Unspecified Organism
This is probably the most commonly used fallback when the exact type of pneumonia isn’t known or specified.
If the provider writes something like “multifocal pneumonia” without identifying a cause, or the documentation doesn’t point to a specific organism, this is usually the safe choice.
Use this when:
- The note says “multifocal pneumonia” but doesn’t specify bacterial, viral, or other causes
- Labs and cultures are still pending
- Imaging shows bilateral infiltrates or multiple opacities, but no confirmed etiology
2. J18.1 – Lobar Pneumonia, Unspecified Organism
Yes, it says “lobar,” but it’s often used when documentation indicates localized pneumonia, including when it involves multiple lobes.
Multifocal doesn’t always mean widespread or bilateral. If the radiology report mentions multiple lobes on one side, this might be appropriate.
Use this when:
- Imaging specifies more than one lobe, but only in one lung
- No causative agent is identified
- Documentation reflects consolidation in defined areas
3. J15.9 – Bacterial Pneumonia, Unspecified
If the provider clearly states it’s bacterial — but doesn’t identify the specific organism — this is your go-to.
Use this when:
- The chart says “bacterial multifocal pneumonia.”
- Sputum or blood cultures are inconclusive or pending
- Empiric antibiotics are being used without a confirmed pathogen
4. J12.9 – Viral Pneumonia, Unspecified
Same idea here. If the documentation leans viral, but you don’t have a specific virus identified (and it’s not COVID), this is the best fit.
Use this when:
- Provider suspects viral etiology but hasn’t confirmed
- Flu or RSV is suspected but not tested/confirmed
- Imaging shows diffuse or patchy infiltrates, and symptoms suggest a viral illness
5. J12.82 – Pneumonia Due to COVID-19
This is now a very common code when multifocal pneumonia is part of a COVID diagnosis. It reflects pneumonia confirmed as being related to the SARS-CoV-2 virus.
Use this when:
- COVID-19 is confirmed (lab test or documented diagnosis)
- Imaging shows bilateral or multifocal infiltrates
- Clinical picture supports COVID pneumonia
Always pair this with U07.1 for the actual COVID diagnosis.
6. J69.0 – Pneumonitis Due to Inhalation of Food and Vomit (Aspiration Pneumonia)
Aspiration pneumonia can also appear as multifocal, especially in patients with dysphagia or altered consciousness.
Use this when:
- The note says “aspiration pneumonia” or “suspected aspiration”.
- Imaging shows posterior or dependent lobe involvement
- There’s a clinical history of choking, vomiting, or feeding-related issues
How to Code When Multifocal Pneumonia Is Documented but the Cause Is Unclear
Sometimes, the only thing you’ve got to work with is a radiology report that says “multifocal opacities” and a provider note that doesn’t get much more specific than “pneumonia.” No confirmed organism. No viral test. Cultures still pending.
Now what?
Don’t Over-Assume — Use J18.9 When in Doubt
In situations where there’s no confirmed pathogen, no clear etiology, and the documentation doesn’t specify whether the pneumonia is bacterial, viral, or aspiration-related, the most appropriate code is:
J18.9 – Pneumonia, Unspecified Organism
It might feel vague, but ICD-10 allows this when the clinical picture supports pneumonia and the cause hasn’t been confirmed yet. It’s also clean code for payers, which is widely accepted and unlikely to raise red flags when properly documented.
Avoid Guessing Based on Treatment Alone
Just because the patient is on antibiotics doesn’t automatically mean it’s bacterial. And just because they have cold-like symptoms doesn’t mean it’s viral.
Treatment plans should always support the code, but they’re not enough on their own. Let the provider’s documented assessment drive the choice of ICD-10.
If You’re Waiting on Test Results, Code What You Know
Pending a confirmed lab doesn’t mean you can’t code the visit.
Go with the most specific code available based on what’s documented today.
If additional info comes in later (like a confirmed pathogen), you can update the claim or append with a corrected diagnosis if needed.
Push for Better Documentation When You Can
If your providers frequently write vague terms like “multifocal pneumonia” without identifying cause or laterality, that’s a great opportunity for internal education.
You can’t code what isn’t written — but you can encourage better habits:
- Ask for specificity (bacterial, viral, aspiration, etc.)
- Clarify laterality (right, left, or bilateral)
- Encourage documentation of clinical reasoning (“suspect aspiration due to dysphagia”)
Clearer notes = better coding = fewer denials.
Common Documentation Pitfalls That Lead to the Wrong ICD-10 Code
Multifocal pneumonia doesn’t just require good clinical judgment — it also demands clear, specific documentation.
Otherwise, even the best-intentioned coding can lead to the wrong ICD-10, resulting in denials, incorrect grouping, or underreporting of severity.
Let’s look at the most common documentation mistakes and how to avoid them.
1. Vague Language Like “Pneumonia” Without Details
“Pneumonia” on its own doesn’t tell us:
- What kind?
- What caused it?
- Where is it located?
- How severe is it?
If the provider only writes “pneumonia,” the coder is forced to default to J18.9, which is fine if that’s truly all we know, but not ideal if more detail is actually available.
Better: “Multifocal pneumonia, likely bacterial, bilateral opacities seen on chest X-ray.”
2. No Mention of Etiology Even When Labs Are Available
Sometimes the lab report is right there, confirming streptococcus pneumoniae, influenza A, or even COVID, but the provider never ties it back to the diagnosis.
If the documentation doesn’t explicitly state the connection, coders often have to play it safe with “unspecified” codes, even when the cause is known.
Fix: Encourage providers to link test results directly to the diagnosis.
“Pneumonia due to confirmed COVID-19 infection (U07.1 + J12.82)”
3. Confusing Laterality or Distribution
“Multifocal” should prompt some clarification:
Are we talking about both lungs? Multiple lobes on the same side? Upper and lower segments?
Without that detail, it’s hard to defend coding for bilateral disease or justify higher-severity groupings.
Better: “Bilateral multifocal pneumonia involving lower lobes.”
4. Using the Term “Multifocal” Without Defining the Pattern
Providers often copy-paste terms from radiology reports, like “multifocal opacities” — without clarifying what that means in their assessment.
A coder can’t assume “multifocal” = bilateral or severe. They need the provider to define what’s meant and how it impacts care decisions.
Fix: Document what “multifocal” means clinically:
“Infiltrates noted in both upper and lower lobes, suggesting diffuse involvement.”
5. Forgetting to Update the Code After New Info Comes In
Maybe the initial documentation was vague, so the coder billed J18.9. But now there’s a confirmed organism or a clarified diagnosis.
If that info doesn’t get looped back to coding or billing, the claim may underrepresent the condition’s complexity and miss out on more appropriate reimbursement.
Fix: Build a process for updating diagnosis codes based on new information, even post-discharge or post-visit. Coders and billers should have a clear workflow for these updates.
How Pneumonia Coding Affects DRG and Reimbursement
ICD-10 codes don’t just live on claim forms — they directly influence how hospitals and inpatient services are reimbursed. That’s especially true for conditions like pneumonia, which are part of common Diagnosis-Related Groups (DRGs).
Let’s unpack how the code you choose for multifocal pneumonia can change what your organization gets paid.
DRGs for Pneumonia: The Basics
Inpatient admissions for pneumonia typically fall into one of these Medicare Severity DRG categories:
- DRG 193: Simple pneumonia and pleurisy with major complications or comorbidities (MCC)
- DRG 194: Simple pneumonia and pleurisy with complications or comorbidities (CC)
- DRG 195: Simple pneumonia and pleurisy without CC/MCC
The ICD-10 code you assign — and what other diagnoses are captured — determines which DRG the case lands in. And each step up adds significantly more reimbursement.
How Multifocal Pneumonia Impacts DRG Assignment
When a provider clearly documents bilateral or multifocal pneumonia, it’s more likely to:
- Reflect higher severity
- Justify the inclusion of complications or comorbidities (CCs)
- Qualify for MCCs when tied to respiratory failure or sepsis
This documentation can push a case from DRG 195 (lowest) to DRG 194 or 193, resulting in thousands more in reimbursement, and more accurately reflecting the resource intensity of care.
The Danger of Vague Coding
If “pneumonia” is coded generically without clear supporting detail, it can cause:
- A lower-weighted DRG, even if the patient had bilateral or severe disease
- Lost revenue due to misclassification
- Audits or medical necessity denials if the coding doesn’t match the clinical picture
Coders can only work with what’s documented. So if a multifocal case is coded as basic pneumonia, your DRG will follow suit — even if your clinical team did way more work.
Final Tip: Get CDI and Coding Working Together
Want cleaner claims and more accurate DRG capture? Bring your clinical documentation improvement (CDI) team and coders into alignment.
Train providers to recognize when pneumonia documentation impacts DRG. Build templates that prompt specificity. And regularly audit pneumonia cases to catch under-coded scenarios.
Final Checklist: Are You Coding Multifocal Pneumonia Correctly?
Before you submit that claim or finalize that inpatient chart, run through this quick list:
- Is the provider using specific language beyond just “pneumonia”?
- Is the etiology (bacterial, viral, aspiration, etc.) clearly documented or confirmed?
- Is the ICD-10 code aligned with what’s actually in the chart?
- Does documentation clarify whether it’s bilateral or multilobar?
- Are you using J18.9 only when no other detail is available?
- If the patient has a known pathogen (like COVID or strep), is that reflected in the code?
- Has the coding team looped back to update the claim if new info (labs or imaging) came in post-discharge?
Get these answers right, and you’re not just avoiding denials — you’re making sure the clinical story is accurately told, and the work your team put in is fully reflected in reimbursement.
Ready to Level Up Your Coding?
At Cadence Collaborative, we help teams streamline the messy, high-stakes parts of medical billing, ICD-10 coding, and revenue cycle management — especially for complex inpatient conditions like pneumonia.
Whether you need help cleaning up documentation workflows, aligning coding with reimbursement strategy, or just getting fewer denials, our team’s ready to dive in. Contact us today!
