2027 ICD-10-CM Diagnosis Code T61.781SOther shellfish poisoning, accidental (unintentional), sequela
T61.781S is a billable ICD-10-CM diagnosis code for other shellfish poisoning, 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. Coders also document this condition as accidental poisoning from shellfish. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Poisoning/toxic effect/adverse effects/underdosing, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
T61.781S 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).
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 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 T61.781S: its own notes plus those printed at T61, 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.
- allergic reaction to food, such as:
- anaphylactic reaction or shock due to adverse food reaction (T78.0-)
- bacterial foodborne intoxications (A05.-)
- dermatitis (L23.6, L25.4, L27.2)
- food protein-induced enterocolitis syndrome (K52.21)
- food protein-induced enteropathy (K52.22)
- gastroenteritis (noninfective) (K52.29)
- toxic effect of aflatoxin and other mycotoxins (T64)
- toxic effect of cyanides (T65.0-)
- toxic effect of harmful algae bloom (T65.82-)
- toxic effect of hydrogen cyanide (T57.3-)
- toxic effect of mercury (T56.1-)
- toxic effect of red tide (T65.82-)
- 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.
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify any retained foreign body, if applicable (Z18.-)
Notes
General instructions on how these codes are used.
- 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.
- 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.
- The appropriate 7th character is to be added to each code from category T61
- Ainitial encounter
- Dsubsequent encounter
- Ssequela this code
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name T61.781S, its category, or a range that includes it.
Excludes2 3
These codes carry an Excludes2 note naming T61.781S: its condition is not part of those codes, and both may be reported when the patient has both.
- T63 Toxic effect of contact with venomous animals and plantsingestion of toxic animal or plant (T61.-, T62.-) names T61.-, which includes this code
- T63.5 Toxic effect of contact with venomous fishpoisoning by ingestion of fish (T61.-) names T61.-, which includes this code
- T63.6 Toxic effect of contact with other venomous marine animalspoisoning by ingestion of shellfish (T61.78-) names T61.78-, which includes this code
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.
| Substance | Accidental | Self-harm | Assault | Undetermined | Adverse Effect | Underdosing |
|---|---|---|---|---|---|---|
| Fish, noxious, nonbacterial::shell | T61.781 | T61.782 | T61.783 | T61.784 | – | – |
| Food, foodstuffs, noxious, nonbacterial, NEC::shellfish | T61.781 | T61.782 | T61.783 | T61.784 | – | – |
| Mussel, noxious | T61.781 | T61.782 | T61.783 | T61.784 | – | – |
| Shellfish, noxious, nonbacterial | T61.781 | T61.782 | T61.783 | T61.784 | – | – |
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 T61.781S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T61.781SOverview
What is the ICD-10 code for other shellfish poisoning, accidental (unintentional), sequela?
The ICD-10-CM code for other shellfish poisoning, accidental (unintentional), sequela is T61.781S (sometimes written as T61781S). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is T61.781S (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), sequela on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character S in T61.781S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the other shellfish poisoning, accidental (unintentional) itself has resolved, not the original event.
What MS-DRG does T61.781S group to?
When other shellfish poisoning, 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 T61.781S 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 other shellfish poisoning, 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.
