2026 ICD-10-CM Diagnosis Code A33Tetanus neonatorum

ICD-10-CM Codes›A00–B99›A30-A49›A33

ICD-10-CM A33
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A33 is a billable ICD-10-CM diagnosis code for tetanus neonatorum. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 794. 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 18 closely related codes. The code is restricted by the Medicare Code Editor to newborn patients (age 0). Coders also document this condition as autonomic disorder due to tetanus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Perinatal infections.

Code Identity

ICD-10-CM Code
A33
Billable Status
Yes — Valid for Submission
Code Describes
Tetanus neonatorum
Short Description
Tetanus neonatorum
Same as the full description in the CMS dataset.
Chapter
A30-A49
Other bacterial diseases

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA33Tetanus neonatorum
This CodeA33Tetanus neonatorum

Code EditsBilling

Medicare Code Editor checks that affect claim validity for A33.

Perinatal / Newborn diagnoses
The Medicare Code Editor detects inconsistencies in perinatal / newborn cases by checking a patient's age and any diagnosis on the patient's record. The newborn code edits apply to patients age 0 years only; a subset of diagnoses which will only occur during the perinatal or newborn period of age 0 (e.g., tetanus neonatorum, health examination for newborn under 8 days old).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Autonomic disorder due to tetanus
  • Disorder of autonomic nervous system due to infectious disease
  • Localized tetanus
  • Omphalitis
  • Tetanic opisthotonus
  • Tetanus neonatorum
  • Tetanus omphalitis
  • Tetanus with trismus
  • Trismus
  • Trismus present

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient No · outpatient No
CCSR PNL009
Perinatal infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Trismus

    spasmodic contraction of the masseter muscle resulting in forceful jaw closure. this may be seen with a variety of diseases, including tetanus, as a complication of radiation therapy, trauma, or in association with neoplastic conditions.

  • Tetanus

    a disease caused by tetanospasmin, a powerful protein toxin produced by clostridium tetani. tetanus usually occurs after an acute injury, such as a puncture wound or laceration. generalized tetanus, the most common form, is characterized by tetanic muscular contractions and hyperreflexia. localized tetanus presents itself as a mild condition with manifestations restricted to muscles near the wound. it may progress to the generalized form.

  • Omphalitis

    inflammation of the umbilical cord stump in newborns.

  • Funisitis

    an acute inflammation of the umbilical cord. it is characterized by the presence of polymorphonuclear cells migrating from the fetal umbilical cord vessels through the umbilical cord towards the bacteria containing amniotic fluid.

  • Necrotizing Funisitis|Sclerosing Funisitis|Sclerosing Funisitis

    a ring of karyorrhectic debris that may exhibit dystrophic mineralization and/or identifiable fetal neutrophil infiltrate in wharton's jelly that is oriented towards the amniotic surface. the cord has a denser ring externally and a fainter ring centrally.

  • Grade 1 Trismus, CTCAE|CTCAE Grade 1 Trismus (difficulty, restriction or pain when opening mouth)|Grade 1 Trismus|Grade 1 Trismus (difficulty, restriction or pain when opening mouth)

    decreased rom (range of motion) without impaired eating

  • Grade 2 Trismus, CTCAE|CTCAE Grade 2 Trismus (difficulty, restriction or pain when opening mouth)|Grade 2 Trismus|Grade 2 Trismus (difficulty, restriction or pain when opening mouth)

    decreased rom requiring small bites, soft foods or purees

  • Grade 3 Trismus, CTCAE|CTCAE Grade 3 Trismus (difficulty, restriction or pain when opening mouth)|Grade 3 Trismus|Grade 3 Trismus (difficulty, restriction or pain when opening mouth)

    decreased rom with inability to adequately aliment or hydrate orally

  • Trismus

    lack of ability to open the mouth fully due to decreased range of motion of the muscles of mastication. it may be a symptom of tetanus.

  • Trismus, CTCAE|Trismus|Trismus|Trismus (difficulty, restriction or pain when opening mouth)

    a disorder characterized by lack of ability to open the mouth fully due to a decrease in the range of motion of the muscles of mastication.

Patient EducationClinical

Tetanus

Tetanus is a serious illness caused by Clostridium bacteria. The bacteria live in soil, saliva, dust, and manure. The bacteria can enter the body through a deep cut, like those you might get from stepping on a nail, or through a burn.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A33 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
771.3 Tetanus neonatorum
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A33Overview

What is the ICD-10 code for tetanus neonatorum?

The ICD-10-CM code for tetanus neonatorum is A33. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is A33 (Tetanus neonatorum) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report tetanus neonatorum on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A33 group to?

When tetanus neonatorum is the principal diagnosis on an inpatient stay, it groups to MS-DRG 794 (neonate with Other Significant Problems), which carries a relative weight of 1.4759. Higher weights mean higher Medicare reimbursement.

Is A33 a CC or MCC?

CMS lists A33 as an MCC (major complication or comorbidity) for FY 2026. 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 18 closely related codes in its exclusion list.

Who can A33 be reported for?

The Medicare Code Editor checks tetanus neonatorum against patient demographics: this code is intended for newborn patients (age 0). Claims outside these limits are flagged as inconsistent.