2026 ICD-10-CM Diagnosis Code T18.0XXAForeign body in mouth, initial encounter

ICD-10-CM Codes›S00–T88›T15-T19›T18

ICD-10-CM T18.0XXA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T18.0XXA is a billable ICD-10-CM diagnosis code for foreign body in mouth, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 157 through 159. Coders also document this condition as foreign body in mouth. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Effect of foreign body entering opening, initial encounter; External cause codes: intent of injury, accidental/unintentional; and External cause codes: other specified, classifiable and NEC; initial encounter.

Code Identity

ICD-10-CM Code
T18.0XXA
Billable Status
Yes — Valid for Submission
Code Describes
Foreign body in mouth, initial encounter
Short Description
Foreign body in mouth, initial encounter
Same as the full description in the CMS dataset.
Parent Code
T18.0
Foreign body in mouth

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT15-T19Effects of foreign body entering through natural orifice
CategoryT18Foreign body in alimentary tract
This CodeT18.0XXAForeign body in mouth, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Foreign body in mouth
  • Foreign body in oral mucosa
  • Foreign body of oral cavity and salivary gland
  • Gingival foreign body
  • Glass in head
  • Glass in mouth
  • Metal foreign body in mouth
  • Separated endodontic instrument in root canal of tooth

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Foreign body in alimentary tract (T18). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

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

CCSR INJ020
Effect of foreign body entering opening, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR EXT020
External cause codes: intent of injury, accidental/unintentional
Default principal diagnosis: inpatient No · outpatient No
CCSR EXT018
External cause codes: other specified, classifiable and NEC; initial encounter
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Foreign Bodies

If you've ever gotten a splinter or had sand in your eye, you've had experience with a foreign body. A foreign body is something that is stuck inside you but isn't supposed to be there. You may inhale or swallow a foreign body, or you may get one from an injury to almost any part of your body.

Read the full article at MedlinePlus

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

Convert T18.0XXA to ICD-9-CMHistory

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

ICD-9-CM
935.0 Foreign body in mouth
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
E915 FB entering oth orifice
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

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 T18.0XXAOverview

Is T18.0XXA (Foreign body in mouth) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report foreign body in mouth, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T18.0XXA mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for foreign body in mouth, such as an emergency visit or first evaluation.

What MS-DRG does T18.0XXA group to?

When foreign body in mouth, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 157, 158, 159, with relative weights from 0.7085 to 1.7168 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of T18.0XXA?

Under the General Equivalence Mappings, foreign body in mouth, initial encounter converts to ICD-9-CM 935.0 (foreign body in mouth) and E915 (FB entering oth orifice). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.