2026 ICD-10-CM Diagnosis Code T61.781AOther shellfish poisoning, accidental (unintentional), initial encounter
T61.781A is a billable ICD-10-CM diagnosis code for other shellfish poisoning, accidental (unintentional), 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 917 through 918. Coders also document this condition as accidental poisoning from shellfish. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, accidental/unintentional; External cause codes: poisoning by non-drug; and Toxic effects, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Accidental poisoning from shellfish
- Amnesic shellfish poisoning
- Diarrheic shellfish poisoning
- Neurotoxic shellfish poisoning
- Paralytic shellfish poisoning
- Shellfish poisoning caused by Gonyaulax catenella
- Shellfish poisoning caused by Gonyaulax tamarensis
- Toxic effect from eating shellfish
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Toxic effect of noxious substances eaten as seafood (T61). 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.
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.
Patient EducationClinical
Foodborne Illness
Each year, around 48 million people in the United States get sick from contaminated food. Common causes include bacteria and viruses. Less often, the cause may be a parasite or a harmful chemical, such as a high amount of pesticides. Symptoms of foodborne illness depend on the cause. They can be mild or serious. They usually include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T61.781A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T61.781AOverview
Is T61.781A (Other shellfish poisoning, accidental (unintentional)) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other shellfish poisoning, accidental (unintentional), initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T61.781A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for other shellfish poisoning, accidental (unintentional), such as an emergency visit or first evaluation.
What MS-DRG does T61.781A group to?
When other shellfish poisoning, accidental (unintentional), initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T61.781A?
Under the General Equivalence Mappings, other shellfish poisoning, accidental (unintentional), initial encounter converts to ICD-9-CM 988.0 (toxic eff fish/shellfish) and E865.1 (acc poison-shellfish). 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.
