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P37.1 ICD-10-CM Code: Congenital toxoplasmosis

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

Coding at a Glance

Tabular directives
1 inclusion term · 14 Excludes2

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 v43, Appendix B.

  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)

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 P37.1 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on P37.1 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Hydrocephalus due to congenital toxoplasmosis

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Coder workflow for P37.1

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

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).

Official instructions as workflow

  • Excludes2 — not part of P37.1(14 notes)

    Coding workflow: The conditions named in this note are not included in P37.1. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareA50, P77, P78.3, A54.31, A33, Z21

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

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.

Code Overview

Congenital toxoplasmosis is a billable ICD-10-CM diagnosis code (P37.1).

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 (FY2026). 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 P37.1 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 3 Excludes1 notes across 3 chapters: B58 — Toxoplasmosis, G91.4 — Hydrocephalus in diseases classified elsewhere, Q03 — Congenital hydrocephalus.

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: P00.2 — Newborn affected by maternal infectious and parasitic diseases (via P37.-).

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

Referenced by 3 Code First instructions across 3 chapters: G05 — Encephalitis, myelitis and encephalomyelitis in diseases classified elsewhere, H32 — Chorioretinal disorders in diseases classified elsewhere, K77 — Liver disorders in diseases classified elsewhere.

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 (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 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 188 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 791 (MDC 15), DRG 793 (MDC 15).

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

Clinical classification (AHRQ CCSR):PNL009 — Perinatal infections (default); INF009 — Parasitic, other specified and unspecified infections.

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.

M32.14 — Glomerular disease in systemic lupus erythematosus, M32.15 — Tubulo-interstitial nephropathy in systemic lupus erythematosus, M32.19 — Other organ or system involvement in systemic lupus erythematosus, M32.8 — Other forms of systemic lupus erythematosus, M32.9 — Systemic lupus erythematosus, unspecified, P35.2 — Congenital herpesviral [herpes simplex] infection, P35.3 — Congenital viral hepatitis, P35.4 — Congenital Zika virus disease, P35.8 — Other congenital viral diseases, P35.9 — Congenital viral disease, unspecified, P37.0 — Congenital tuberculosis, P37.2 — Neonatal (disseminated) listeriosis, P37.3 — Congenital falciparum malaria, P37.4 — Other congenital malaria, P37.8 — Other specified congenital infectious and parasitic diseases, P37.9 — Congenital infectious or parasitic disease, unspecified, T56.0X1A — Toxic effect of lead and its compounds, accidental (unintentional), initial encounter, T56.0X2A — Toxic effect of lead and its compounds, intentional self-harm, initial encounter, T56.0X3A — Toxic effect of lead and its compounds, assault, initial encounter, T56.0X4A — Toxic effect of lead and its compounds, undetermined, initial encounter, +167 more

Same clinical category (CCSR)

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

P36.10 — Sepsis of newborn due to unspecified streptococci, P36.19 — Sepsis of newborn due to other streptococci, P36.2 — Sepsis of newborn due to Staphylococcus aureus, P36.30 — Sepsis of newborn due to unspecified staphylococci, P36.39 — Sepsis of newborn due to other staphylococci, P36.4 — Sepsis of newborn due to Escherichia coli, P36.5 — Sepsis of newborn due to anaerobes, P36.8 — Other bacterial sepsis of newborn, P36.9 — Bacterial sepsis of newborn, unspecified, P37.0 — Congenital tuberculosis, P37.2 — Neonatal (disseminated) listeriosis, P37.3 — Congenital falciparum malaria, P37.4 — Other congenital malaria, P37.5 — Neonatal candidiasis, P37.8 — Other specified congenital infectious and parasitic diseases, P37.9 — Congenital infectious or parasitic disease, unspecified, P38.1 — Omphalitis with mild hemorrhage, P38.9 — Omphalitis without hemorrhage, P39.0 — Neonatal infective mastitis, P39.1 — Neonatal conjunctivitis and dacryocystitis, +307 more

Same Index main term, other category

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

K75.9 — Inflammatory liver disease, unspecified, M32.19 — Other organ or system involvement in systemic lupus erythematosus (lupus erythematosus, systemic), O29.01 — Aspiration pneumonitis due to anesthesia during pregnancy (postanesthetic, in pregnancy), O33.6 — Maternal care for disproportion due to hydrocephalic fetus (causing disproportion), O66.3 — Obstructed labor due to other abnormalities of fetus (causing disproportion, with obstructed labor), O74.0 — Aspiration pneumonitis due to anesthesia during labor and delivery (aspiration, obstetric), O89.01 — Aspiration pneumonitis due to anesthesia during the puerperium (postanesthetic, postpartum, puerperal), P24.01 — Meconium aspiration with respiratory symptoms (meconium), P35.0 — Congenital rubella syndrome (congenital rubella), P35.3 — Congenital viral hepatitis (viral, virus, congenital), P59.29 — Neonatal jaundice from other hepatocellular damage (newborn), Q02 — Microcephaly, Q03.0 — Malformations of aqueduct of Sylvius (aqueduct Sylvius stricture), Q03.1 — Atresia of foramina of Magendie and Luschka (foramen Magendie block, congenital), Q03.8 — Other congenital hydrocephalus (congenital, specified NEC), Q03.9 — Congenital hydrocephalus, unspecified (newborn), Q05.0 — Cervical spina bifida with hydrocephalus (congenital, with spina bifida, cervical), Q05.1 — Thoracic spina bifida with hydrocephalus (congenital, with spina bifida, dorsal), Q05.2 — Lumbar spina bifida with hydrocephalus (congenital, with spina bifida, lumbar), Q05.3 — Sacral spina bifida with hydrocephalus (congenital, with spina bifida, sacral), +180 more

Contextual Map

Every relationship of P37.1 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 P37.1 with these 7 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes

Referenced by Code First instructions

Clinical classification (CCSR)

MS-DRG Grouper

  • MCC — Major Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (MCC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
  • DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
  • DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

Index entries (14)

  • Chorioretinitis, in (due to), toxoplasmosis (acquired), congenital (active)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Encephalitis (chronic) (hemorrhagic) (idiopathic) (nonepidemic) (spurious) (subacute), in (due to), toxoplasmosis (acquired), congenital[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hepatitis, in (due to), toxoplasmosis (acquired), congenital (active)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Hydrocephalus (acquired) (external) (internal) (malignant) (recurrent), due to toxoplasmosis (congenital)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Infection, infected, infective (opportunistic), congenital, toxoplasmosis (acute) (subacute) (chronic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Lymphadenopathy (generalized), due to toxoplasmosis (acquired), congenital (acute) (subacute) (chronic)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Meningoencephalitis, in (due to), toxoplasmosis (acquired), congenital[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Meningoencephalomyelitis, due to, Toxoplasma or toxoplasmosis (acquired), congenital[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 FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 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 — v43 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. "P37.1 — Congenital toxoplasmosis." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/p37.1-congenital-toxoplasmosis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Congenital toxoplasmosis

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), 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 P37.1 in its code family, with their registry titles.

View all codes in the P37 family