2026 ICD-10-CM Diagnosis Code T81.521AObstruction due to foreign body accidentally left in body following infusion or transfusion, initial encounter

ICD-10-CM Codes›S00–T88›T80-T88›T81

ICD-10-CM T81.521A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T81.521A is a billable ICD-10-CM diagnosis code for obstruction due to foreign body accidentally left in body following infusion or transfusion, 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 919 through 921. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Complication of other surgical or medical care, injury, initial encounter.

Code Identity

ICD-10-CM Code
T81.521A
Billable Status
Yes — Valid for Submission
Code Describes
Obstruction due to foreign body accidentally left in body following infusion or transfusion, initial encounter
Short Description
Obst due to fb acc left in body fol infusn/transfusn, init
Parent Code
T81.521
Obstruction due to foreign body accidentally left in body following infusion or transfusion

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT80-T88Complications of surgical and medical care, not elsewhere classified
CategoryT81Complications of procedures, not elsewhere classified
This CodeT81.521AObstruction due to foreign body accidentally left in body following infusion or transfusion, initial encounter

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Complications of procedures, not elsewhere classified (T81). 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 INJ037
Complication of other surgical or medical care, injury, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

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 T81.521A to ICD-9-CMHistory

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

ICD-9-CM
998.4 FB left during procedure
Approximate The match is approximate rather than exact.

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 T81.521AOverview

Is T81.521A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report obstruction due to foreign body accidentally left in body following infusion or transfusion, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T81.521A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for obstruction due to foreign body accidentally left in body following infusion or transfusion, such as an emergency visit or first evaluation.

What MS-DRG does T81.521A group to?

When obstruction due to foreign body accidentally left in body following infusion or transfusion, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 919, 920, 921, with relative weights from 0.6884 to 1.8308 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of T81.521A?

Under the General Equivalence Mappings, obstruction due to foreign body accidentally left in body following infusion or transfusion, initial encounter converts to ICD-9-CM 998.4 (FB left during procedure). 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.