2027 ICD-10-CM Diagnosis Code T65.851SToxic effect of medetomidine, accidental (unintentional), sequela

ICD-10-CM Codes›S00–T88›T51-T65›T65

ICD-10-CM T65.851S
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

T65.851S is a billable ICD-10-CM diagnosis code for toxic effect of medetomidine, accidental (unintentional), sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 922 through 923. The code is exempt from POA reporting.

Code Identity

ICD-10-CM Code
T65.851S
Billable Status
Yes — Valid for Submission
Code Describes
Toxic effect of medetomidine, accidental (unintentional), sequela
Short Description
Toxic effect of medetomidine, accidental, sequela
Parent Code
T65.851
Toxic effect of medetomidine, accidental (unintentional)

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT51-T65Toxic effects of substances chiefly nonmedicinal as to source
CategoryT65Toxic effect of other and unspecified substances
This CodeT65.851SToxic effect of medetomidine, accidental (unintentional), sequela

Present on Admission (POA)Billing

T65.851S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Toxic effects of substances chiefly nonmedicinal as to source (T51-T65).

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Toxic effect of other and unspecified substances (T65). 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 2027, published by CMS and the National Center for Health Statistics.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to T65.851S: its own notes plus those printed at T65.85, T65, block T51-T65, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From Block T51-T65 Toxic effects of substances chiefly nonmedicinal as to source applies to 1,680 codes
  • contact with and (suspected) exposure to toxic substances (Z77.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes

Use Additional Code

Add a second code, after this one, to fully describe the condition.

From T65.85 Toxic effect of medetomidine applies to 12 codes
  • code to identify associated manifestations, such as:
  • bradycardia NOS (R00.1)
  • somnolence, stupor and coma (R40.-)
From Block T51-T65 Toxic effects of substances chiefly nonmedicinal as to source applies to 1,680 codes
  • code(s):
  • for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
  • personal history of foreign body fully removed (Z87.821)
  • to identify any retained foreign body, if applicable (Z18.-)
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • code to identify any retained foreign body, if applicable (Z18.-)

Notes

General instructions on how these codes are used.

From Block T51-T65 Toxic effects of substances chiefly nonmedicinal as to source applies to 1,680 codes
  • When no intent is indicated code to accidental. Undetermined intent is only for use when there is specific documentation in the record that the intent of the toxic effect cannot be determined.
From Chapter 19 (S00-T88) Injury, poisoning and certain other consequences of external causes applies to 41,187 codes
  • Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
  • The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.

7th Character

Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.

From T65 Toxic effect of other and unspecified substances applies to 192 codes
  • The appropriate 7th character is to be added to each code from category T65
Values for category T65 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter
  • Dsubsequent encounter
  • Ssequela this code

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Clinical InformationClinical

  • Medetomidine

    an agonist of receptors, adrenergic alpha-2 that is used in veterinary medicine for its analgesic and sedative properties. it is the racemate of dexmedetomidine.

Table of Drugs and ChemicalsClinical

Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.

SubstanceAccidentalSelf-harmAssaultUndeter­minedAdverse
Effect		Under­dosing
MedetomidineT65.851T65.852T65.853T65.854––

Code History & ChangesHistory

New Code T65.851S was added to the ICD-10-CM code set for FY 2027, effective October 1, 2026.

Replacement T65.851S replaces the following previously assigned code(s):

  • T65.891S - Toxic effect of substances, accidental, sequela
FY 2027AddedAdded to the ICD-10-CM code setEffective October 1, 2026.
FY 2027CurrentRevised in the current code setEffective October 1, 2026 through September 30, 2027.

Questions About T65.851SOverview

What is the ICD-10 code for toxic effect of medetomidine, accidental (unintentional), sequela?

The ICD-10-CM code for toxic effect of medetomidine, accidental (unintentional), sequela is T65.851S (sometimes written as T65851S). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is T65.851S (Toxic effect of medetomidine, accidental (unintentional)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of medetomidine, accidental (unintentional), sequela on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character S in T65.851S mean?

The final character S makes this a sequela code: it reports a lingering problem that remains after the toxic effect of medetomidine, accidental (unintentional) itself has resolved, not the original event.

What MS-DRG does T65.851S group to?

When toxic effect of medetomidine, accidental (unintentional), sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 923, 922, with relative weights from 0.9980 to 1.6248 depending on complications. Higher weights mean higher Medicare reimbursement.

Is T65.851S exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for toxic effect of medetomidine, accidental (unintentional), sequela on inpatient claims. The code appears in the Toxic effects of substances chiefly nonmedicinal as to source (T51-T65) range of the CMS exempt list.