2026 ICD-10-CM Diagnosis Code T18.5XXAForeign body in anus and rectum, initial encounter

ICD-10-CM Codes›S00–T88›T15-T19›T18

ICD-10-CM T18.5XXA
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T18.5XXA is a billable ICD-10-CM diagnosis code for foreign body in anus and rectum, 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 393 through 395. Coders also document this condition as foreign body in anus. 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
T18.5XXA
Billable Status
Yes — Valid for Submission
Code Describes
Foreign body in anus and rectum, initial encounter
Short Description
Foreign body in anus and rectum, initial encounter
Same as the full description in the CMS dataset.
Parent Code
T18.5
Foreign body in anus and rectum

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 CodeT18.5XXAForeign body in anus and rectum, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Foreign body in anus
  • Foreign body in anus and rectum
  • Foreign body in colon
  • Foreign body in rectosigmoid junction
  • Foreign body in rectum
  • Foreign body in sigmoid colon
  • Foreign body of large intestine

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 T18.5XXA to ICD-9-CMHistory

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

ICD-9-CM
937 Foreign body anus/rectum
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 T18.5XXAOverview

Is T18.5XXA (Foreign body in anus and rectum) a billable code?

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

What does the 7th character A in T18.5XXA mean?

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

What MS-DRG does T18.5XXA group to?

When foreign body in anus and rectum, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 393, 394, 395, with relative weights from 0.6490 to 1.5993 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of T18.5XXA?

Under the General Equivalence Mappings, foreign body in anus and rectum, initial encounter converts to ICD-9-CM 937 (foreign body anus/rectum) 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.