I26.99: Other pulmonary embolism without acute cor pulmonale

The ICD-10-CM code for an acute pulmonary embolism when the record does not document acute cor pulmonale and does not name a septic, saddle, subsegmental, cement or fat embolus.

Billable

FY2027

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At a glance

Code Family

I26: Pulmonary embolism

DRG Grouping

MS-DRG 175 or MS-DRG 176 in MDC 04 under the FY2027 MS-DRG v44 grouper, depending on whether a secondary MCC is reported.

HCC Mapping (v28)

HCC 267: Deep Vein Thrombosis and Pulmonary Embolism.

Condition

Pulmonary embolism

Family Specificity

Twelve billable codes, split first on documented acute cor pulmonale and then on the type of embolus, with I26.99 as the residual entry that carries Pulmonary embolism NOS.

Billable

Yes, a valid five character code. Its parent I26.9 is a subcategory header and cannot be reported.

Which I26 code do I assign?

Category I26 splits first on whether the provider documents acute cor pulmonale: the I26.0- codes carry it and the I26.9- codes do not. Within each branch the fifth character names the embolus itself, whether septic, saddle, subsegmental, cement, fat or other.

When documentation says…

Code

Acute PE with acute cor pulmonale

I26.09

The provider documents acute cor pulmonale alongside the embolism. Acute cor pulmonale is the only axis that moves a case from the I26.9- codes into the I26.0- codes. The note must state it in words.

Saddle embolus at the pulmonary artery bifurcation, no acute cor pulmonale

I26.92

A saddle embolus of the pulmonary artery, without documented acute cor pulmonale. The provider must name the saddle embolus in the record.

Septic pulmonary embolism, no acute cor pulmonale

I26.90

A septic embolus in the pulmonary circulation, without documented acute cor pulmonale. I26.90 carries a Code first note for the underlying infection. Category I26 carries an Excludes2 note for septic (non-pulmonary) arterial embolism (I76).

Single subsegmental thrombotic PE on CT angiography, no acute cor pulmonale

I26.93

A thrombotic embolus confined to a subsegmental pulmonary artery. Assign I26.94 where multiple subsegmental emboli are documented.

Acute pulmonary embolism

I26.99

This is the default code for an acute pulmonary embolism. The FY2027 tabular lists Pulmonary embolism NOS and Acute pulmonary embolism NOS as inclusion terms under I26.99. Assign it where the record documents an acute embolism and names neither acute cor pulmonale nor a septic, saddle, subsegmental, cement or fat embolus.

Chronic pulmonary embolism

I27.82

Chronic pulmonary embolism sits outside category I26 entirely. Category I26 carries an Excludes2 note for I27.82. Both codes may be reported where an acute embolism is documented on top of a chronic one.

History of pulmonary embolism, resolved and off treatment

Z86.711

Personal history of pulmonary embolism. Assign Z86.711 rather than I26.99 once the embolism has resolved and treatment has ended. Code I27.82 carries an Excludes1 note for Z86.711, which means chronic pulmonary embolism and personal history of pulmonary embolism are not reported together for the same condition.

Tabular notes

EXCLUDES1

Category I26 carries one Excludes1 note: cor pulmonale without embolism (I27.81). An Excludes1 note means the two codes are not reported together for the same condition. A patient with chronic cor pulmonale and no documented embolism belongs in I27.81 rather than in category I26. There is no separate code for acute cor pulmonale on its own. The condition is captured only inside the I26.0- codes.

EXCLUDES2

Category I26 carries Excludes2 notes for chronic pulmonary embolism (I27.82), personal history of pulmonary embolism (Z86.711), pulmonary embolism complicating abortion, ectopic or molar pregnancy (O00–O07, O08.2), pulmonary embolism complicating pregnancy, childbirth and the puerperium (O88.-), pulmonary embolism due to trauma (T79.0, T79.1), pulmonary embolism due to complications of surgical and medical care (T80.0, T81.7-, T82.8-), and septic (non-pulmonary) arterial embolism (I76). An Excludes2 note means the excluded condition is not part of I26.99. The patient may carry both conditions. Both codes may be reported where both are documented. An embolism arising in pregnancy, childbirth or the puerperium is described by the O88.2- codes in Chapter 15.

FY2027: EFFECTIVE 1 OCTOBER 2026

The FY2027 codes addenda make no addition, deletion or revision in category I26. The FY2027 tabular addenda make no change to the I26 or I26.99 instructional notes. I26.99 is unchanged in the FY2027 update.

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

HCC 267: Deep Vein Thrombosis and Pulmonary Embolism.

Code I26.99 maps to HCC 267 in the CMS-HCC v28 ICD-10-CM mapping.

Code I27.82, chronic pulmonary embolism, maps to the same HCC 267.

Code Z86.711, personal history of pulmonary embolism, maps to no HCC. A resolved embolism carries no risk adjustment weight.

For Medicare Advantage risk adjustment, the diagnosis must appear on a dated encounter note from the calendar year rather than only on a problem list.

MS-DRG v44 (FY2027)

MS-DRG 175: Pulmonary Embolism with MCC or Acute Cor Pulmonale.

MS-DRG 176: Pulmonary Embolism without MCC.

Both MS-DRGs sit in MDC 04, Diseases and Disorders of the Respiratory System.

With I26.99 as the principal diagnosis, the case groups to MS-DRG 176 unless a secondary diagnosis on the MCC list is also reported. A reported secondary MCC moves the case to MS-DRG 175.

Under the FY2027 MS-DRG v44 grouper, a principal diagnosis from the I26.0- codes groups to MS-DRG 175 without any MCC. The v44 title of MS-DRG 175, Pulmonary Embolism with MCC or Acute Cor Pulmonale, names acute cor pulmonale as an alternative to an MCC.

Reported as a secondary diagnosis, I26.99 carries MCC severity under Appendix C of the FY2027 MS-DRG Definitions Manual, Version 44.0. Code I27.82 carries CC severity in the same appendix.

A principal diagnosis never acts as its own MCC. Reporting I26.99 first does not by itself produce MS-DRG 175.

Version 44.0 of the grouper applies to discharges on or after 1 October 2026.

Medicare and commercial payers

These MS-DRG rules apply to Medicare Fee for Service inpatient claims. The CMS-HCC v28 rules apply to Medicare Advantage plans for payment year 2026.

Code I26.99 is complete at five characters and needs no further characters.

WHERE SPECIFICITY IS LOST

Where the provider documented acute cor pulmonale and I26.99 was assigned instead of an I26.0- code, the case loses the MS-DRG 175 assignment that the I26.0- codes carry on their own.

Where the embolism has resolved and I26.99 was assigned instead of Z86.711, the claim reports an active acute condition. The Index sends a healed or old pulmonary embolism to Z86.711.

Where the provider documented chronic pulmonary embolism and I26.99 was assigned, the record misses I27.82. Both codes map to HCC 267, which leaves the risk adjustment value unchanged. The severity designation differs. Code I26.99 is an MCC and I27.82 is a CC.

Where the record names a saddle embolus and I26.99 was assigned, the claim loses I26.92.

SEVERITY DESIGNATION (MS-DRG V44.0)

I26.99 is an MCC. It appears in Appendix H, diagnoses defined as major complications or comorbidities, in the ICD-10 MS-DRG Definitions Manual Version 44.0. As a secondary diagnosis it can move a case to the with-MCC tier of its DRG pair.

Documentation checklist to support I26.99

Chart elements that support code selection and reduce specificity-driven denials.

A provider statement of pulmonary embolism, with the acuity documented as acute.

An explicit statement of whether acute cor pulmonale is present. The absence of acute cor pulmonale is what places the case in the I26.9- codes.

The embolus type where it is known: septic, saddle, subsegmental, cement or fat. Naming none of these supports I26.99.

The imaging that established the embolism, such as CT pulmonary angiography, referenced in the provider note rather than left in the radiology report alone.

Anticoagulation started or continued, to support Z79.01 where long term current use applies.

For an embolism arising in pregnancy, childbirth or the puerperium, the timing detail needed for a code from the O88.2- group.

For a prior embolism, whether it has resolved and whether treatment has ended. That is what separates Z86.711 from an active code.

For outpatient encounters, a confirmed diagnosis. A probable or suspected pulmonary embolism is not coded as confirmed in the outpatient setting.

FAQ

Why is an ordinary acute pulmonary embolism coded I26.99 rather than something more generic?

The FY2027 tabular puts the generic terms there. Under I26.99 it lists three inclusion terms: Acute pulmonary embolism NOS, Pulmonary embolism NOS, and Other thrombotic pulmonary embolism without acute cor pulmonale. The descriptor reads Other pulmonary embolism without acute cor pulmonale because Other is the residual slot inside the I26.9- branch. Category I26 has no code titled unspecified pulmonary embolism. Code I26.99 is the entry that does that work.

Is I26.99 a billable code?

Yes. Code I26.99 is a valid five character billable code. Its parent I26.9, pulmonary embolism without acute cor pulmonale, is a subcategory header and cannot be reported on a claim. Category I26 as a whole cannot be reported either.

When do I use I27.82 instead of I26.99?

Use I27.82 where the provider documents chronic pulmonary embolism. The chronic form sits in category I27, not in category I26. Category I26 carries an Excludes2 note for I27.82. Both codes may be reported where an acute embolism is documented on top of a chronic one. Code I27.82 also carries its own instruction to add Z79.01 for associated long term current use of anticoagulants.

Where does a resolved pulmonary embolism go?

A resolved pulmonary embolism goes to Z86.711, personal history of pulmonary embolism. Category I26 carries an Excludes2 note for Z86.711. Assigning I26.99 for an embolism that has resolved reports an active acute condition on the claim. Code I27.82 carries an Excludes1 note for Z86.711, which means chronic pulmonary embolism and personal history of pulmonary embolism are not reported together for the same condition.

Does I26.99 map to an HCC under CMS-HCC v28?

Yes. Code I26.99 maps to HCC 267, Deep Vein Thrombosis and Pulmonary Embolism, in the CMS-HCC v28 ICD-10-CM mapping. Code I27.82 maps to the same HCC. Code Z86.711 maps to no HCC.

Is I26.99 a CC or an MCC?

Reported as a secondary diagnosis, I26.99 carries MCC severity under Appendix C of the FY2027 MS-DRG Definitions Manual, Version 44.0. Code I27.82 carries CC severity in the same appendix. Severity designation and HCC mapping are separate questions and must be checked separately.

How is I26.99 sequenced on an inpatient claim?

Under Section II of the FY2027 ICD-10-CM Official Guidelines, the principal diagnosis is the condition established after study to be chiefly responsible for the admission. Where the embolism is the reason for admission, I26.99 is sequenced first and the case groups to MS-DRG 175 or MS-DRG 176. Where the embolism develops during a stay for another condition, it is reported as a secondary diagnosis. In the outpatient setting a suspected embolism is not coded as confirmed. On the inpatient side a diagnosis documented as probable or suspected at the time of discharge is coded as confirmed.

What changed for I26.99 in FY2027?

I26.99 is unchanged in the FY2027 update. The FY2027 update, effective 1 October 2026, makes no addition, deletion or revision in category I26 and no change to its instructional notes.

Related codes

Codes in the same family as I26.99. Only codes with a published page render as links.

Sibling codes in the I26 family

I26.01: Septic pulmonary embolism with acute cor pulmonale.
I26.02: Saddle embolus of pulmonary artery with acute cor pulmonale.
I26.03: Cement embolism of pulmonary artery with acute cor pulmonale.
I26.04: Fat embolism of pulmonary artery with acute cor pulmonale.
I26.09: Other pulmonary embolism with acute cor pulmonale.
I26.90: Septic pulmonary embolism without acute cor pulmonale.
I26.92: Saddle embolus of pulmonary artery without acute cor pulmonale.
I26.93: Single subsegmental thrombotic pulmonary embolism without acute cor pulmonale.
I26.94: Multiple subsegmental thrombotic pulmonary emboli without acute cor pulmonale.
I26.95: Cement embolism of pulmonary artery without acute cor pulmonale.
I26.96: Fat embolism of pulmonary artery without acute cor pulmonale.

Additional codes to consider

Codes outside the I26 family considered alongside I26.99.

Companion: code alongside when documented

I27.24: Chronic thromboembolic pulmonary hypertension, which carries its own instruction to code the associated pulmonary embolism.
Z79.01: Long term (current) use of anticoagulants, when the provider documents anticoagulant therapy for an extended period (Guideline I.C.21.c.3).

Consider instead

I26.09: Other pulmonary embolism with acute cor pulmonale, where the provider documents acute cor pulmonale.
I26.92: Saddle embolus of pulmonary artery without acute cor pulmonale, where the record names a saddle embolus.
I27.82: Chronic pulmonary embolism.
Z86.711: Personal history of pulmonary embolism, where the embolism has resolved and treatment has ended.
I27.81: Cor pulmonale (chronic), where no embolism is documented.
O88.2-: Obstetric thromboembolism, for an embolism arising in pregnancy, childbirth or the puerperium.
T79.1XX-: Fat embolism (traumatic).
T80.0XX-: Air embolism following infusion, transfusion and therapeutic injection.
I76: Septic arterial embolism, for a septic embolism outside the pulmonary circulation.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software