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B50.9 ICD-10-CM Code: Plasmodium falciparum malaria, unspecified

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term · 2 Excludes1

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 867 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH MCC (MDC 18)
  • MS-DRG 868 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITH CC (MDC 18)
  • MS-DRG 869 — OTHER INFECTIOUS AND PARASITIC DISEASES DIAGNOSES WITHOUT CC/MCC (MDC 18)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B50.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on B50.9 itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • mixed infections of Plasmodium falciparum with any other Plasmodium species

Source: inherited from B50

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Source: inherited from B50-B64

Coder workflow for B50.9

MedCoder structured workflow — derived from this code’s own official record

Before you code B50.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, B50.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewB50.0, B50.8

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with B50.9. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — B50.9 is appropriate when the documentation goes no further.

    ReviewB50.0, B50.8

  2. Does the documentation support a condition named in B50.9’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewA06, A07

Consider B50.9. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting B50.9(2 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with B50.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareA06, A07

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewB50.0, B50.8

Documentation: Both the condition B50.9 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewA06, A07

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse B50.9 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of B50.9 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • A06— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of amebiasis moves the case to A06; the two are not reported together unless documented as unrelated.

    Full comparison: B50.9 vs A06 →

  • A07— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of other protozoal intestinal diseases moves the case to A07; the two are not reported together unless documented as unrelated.

    Full comparison: B50.9 vs A07 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Code Overview

Plasmodium falciparum malaria, unspecified is a billable ICD-10-CM diagnosis code (B50.9).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (14)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • MCC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name B50.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 4 Excludes1 notes: B51 — Plasmodium vivax malaria (via B50.-), B52 — Plasmodium malariae malaria (via B50.-), B53.0 — Plasmodium ovale malaria (via B50.-), B53.1 — Malaria due to simian plasmodia (via B50.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: J82 — Pulmonary eosinophilia, not elsewhere classified (via B50.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 2 Code First instructions: D63.8 — Anemia in other chronic diseases classified elsewhere (via B50.-), D77 — Other disorders of blood and blood-forming organs in diseases classified elsewhere (via B50.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: MCC — Major Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 32 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 867 (MDC 18), DRG 868 (MDC 18), DRG 869 (MDC 18).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INF009 — Parasitic, other specified and unspecified infections (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as MCC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

B50.0 — Plasmodium falciparum malaria with cerebral complications, B50.8 — Other severe and complicated Plasmodium falciparum malaria, B51.0 — Plasmodium vivax malaria with rupture of spleen, B51.8 — Plasmodium vivax malaria with other complications, B51.9 — Plasmodium vivax malaria without complication, B52.0 — Plasmodium malariae malaria with nephropathy, B52.8 — Plasmodium malariae malaria with other complications, B52.9 — Plasmodium malariae malaria without complication, B53.0 — Plasmodium ovale malaria, B53.1 — Malaria due to simian plasmodia, B53.8 — Other malaria, not elsewhere classified, B54 — Unspecified malaria, B55.0 — Visceral leishmaniasis, B55.1 — Cutaneous leishmaniasis, B55.2 — Mucocutaneous leishmaniasis, B55.9 — Leishmaniasis, unspecified, B56.0 — Gambiense trypanosomiasis, B56.1 — Rhodesiense trypanosomiasis, B56.9 — African trypanosomiasis, unspecified, B57.0 — Acute Chagas' disease with heart involvement, +11 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Parasitic, other specified and unspecified infections).

A77.8 — Other spotted fevers, A77.9 — Spotted fever, unspecified, A79.0 — Trench fever, A79.1 — Rickettsialpox due to Rickettsia akari, A79.81 — Rickettsiosis due to Ehrlichia sennetsu, A79.82 — Anaplasmosis [A. phagocytophilum], A79.89 — Other specified rickettsioses, A79.9 — Rickettsiosis, unspecified, B50.0 — Plasmodium falciparum malaria with cerebral complications, B50.8 — Other severe and complicated Plasmodium falciparum malaria, B51.0 — Plasmodium vivax malaria with rupture of spleen, B51.8 — Plasmodium vivax malaria with other complications, B51.9 — Plasmodium vivax malaria without complication, B52.0 — Plasmodium malariae malaria with nephropathy, B52.8 — Plasmodium malariae malaria with other complications, B52.9 — Plasmodium malariae malaria without complication, B53.0 — Plasmodium ovale malaria, B53.1 — Malaria due to simian plasmodia, B53.8 — Other malaria, not elsewhere classified, B54 — Unspecified malaria, +235 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Malaria, malarial”, “Fever”; these codes share that main term but sit in a different category of the Tabular List.

A98.2 — Kyasanur Forest disease (hemorrhagic NOS, Kyasanur forest), A98.5 — Hemorrhagic fever with renal syndrome (Songo), A98.8 — Other specified viral hemorrhagic fevers (hemorrhagic NOS, viral, specified NEC), A99 — Unspecified viral hemorrhagic fever (hemorrhagic NOS, viral), B00.1 — Herpesviral vesicular dermatitis (sore), B08.8 — Other specified viral infections characterized by skin and mucous membrane lesions (aphthous), B30.2 — Viral pharyngoconjunctivitis (pharyngoconjunctival), B33.1 — Ross River disease (Ross River), B33.8 — Other specified viral diseases (Tahyna), B38.0 — Acute pulmonary coccidioidomycosis (desert), B51.0 — Plasmodium vivax malaria with rupture of spleen (vivax, with, ruptured spleen), B51.8 — Plasmodium vivax malaria with other complications (vivax, with, complications NEC), B51.9 — Plasmodium vivax malaria without complication (vivax), B52.0 — Plasmodium malariae malaria with nephropathy (malariae, with, glomerular disorder), B52.8 — Plasmodium malariae malaria with other complications (malariae, with, complications NEC), B52.9 — Plasmodium malariae malaria without complication (quartan), B53.0 — Plasmodium ovale malaria (Plasmodium ovale), B53.1 — Malaria due to simian plasmodia (Plasmodium, simian), B53.8 — Other malaria, not elsewhere classified (specified type NEC), B54 — Unspecified malaria, +118 more

Contextual Map

Every relationship of B50.9 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run B50.9 with these 7 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

  • B51 — Plasmodium vivax malaria[Excludes1](via B50.-): “plasmodium vivax with Plasmodium falciparum (B50.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • B52 — Plasmodium malariae malaria[Excludes1](via B50.-): “Plasmodium falciparum (B50.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • B53.0 — Plasmodium ovale malaria[Excludes1](via B50.-): “Plasmodium ovale with Plasmodium falciparum (B50.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
  • B53.1 — Malaria due to simian plasmodia[Excludes1](via B50.-): “Malaria due to simian plasmodia with Plasmodium falciparum (B50.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes

Referenced by Code First instructions

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites[MDC crossing]: “Infectious and Parasitic Diseases, Systemic or Unspecified Sites — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries (14)

  • Chagres fever[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Estivo-autumnal malaria (fever)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), Chagres[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), continued malarial[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), estivo-autumnal (malarial)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), intermittent (bilious), pernicious[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), Panama (malarial)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), subtertian[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 6 more

Nearest codes

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "B50.9 — Plasmodium falciparum malaria, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/b50.9-plasmodium-falciparum-malaria-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Plasmodium falciparum malaria, unspecified

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to B50.9 in its code family, with their registry titles.

View all codes in the B50 family