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T65.851S vs Z77

T65.851S (Toxic effect of medetomidine, accidental (unintentional), sequela) compared with Z77 (Other contact with and (suspected) exposures hazardous to health), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.

Relationship

Conflict

Excludes1 conflict

T65.851S
Toxic effect of medetomidine, accidental (unintentional), sequela
↔
Z77
Other contact with and (suspected) exposures hazardous to health

Not coded here — these two are mutually exclusive.

“contact with and (suspected) exposure to toxic substances (Z77.-)”

An Excludes1 note means the two conditions cannot occur together, so the pair should not be reported for the same encounter. The sole exception is when the conditions are documented as unrelated to each other.

Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Informational

Excludes2 relationship

Z77
Other contact with and (suspected) exposures hazardous to health
↔
T65.851S
Toxic effect of medetomidine, accidental (unintentional), sequela

Distinct conditions — both may be reported.

“toxic effects of substances chiefly nonmedicinal as to source (T51-T65)”

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source: CMS ICD-10-CM tabular instructional notes

Can these codes be reported together?

No — do not report together. T65.851S carries an Excludes1 note covering Z77: “contact with and (suspected) exposure to toxic substances (Z77.-)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Yes, when both are documented. Z77 carries an Excludes2 note covering T65.851S: “toxic effects of substances chiefly nonmedicinal as to source (T51-T65)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

Side by side

T65.851SToxic effect of medetomidine, accidental (unintentional), sequelaZ77Other contact with and (suspected) exposures hazardous to health
Billing statusBillableNon-billable header

Report instead: Z77.010, Z77.011, Z77.012, Z77.013, Z77.018

ClassificationS00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)Z00-Z99 — Factors Influencing Health Status and Contact with Health Services (Z00-Z99)
Definition—Other contact with and (suspected) exposures hazardous to health is a non-billable ICD-10-CM category code (Z77).
7th characterThe appropriate 7th character is to be added to each code from category T65—
Includes
Toxic effect of medetomidine NOS
contact with and (suspected) exposures to potential hazards to health
Use additional code
code to identify associated manifestations, such as:
bradycardia NOS (R00.1)
somnolence, stupor and coma (R40.-)
—
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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources