2027 ICD-10-CM Diagnosis Code T63.422AToxic effect of venom of ants, intentional self-harm, initial encounter
T63.422A is a billable ICD-10-CM diagnosis code for toxic effect of venom of ants, intentional self-harm, 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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 917 through 918. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: bites; initial encounter; External cause codes: intent of injury, self-harm; and Suicidal ideation/attempt/intentional self-harm.
For Medicare Advantage risk adjustment, T63.422A maps to CMS-HCC Category 155 (Major Depression, Moderate or Severe, without Psychosis) under the V28 model, adding a risk factor of about 0.299 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
T63.422A maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Toxic effect of contact with venomous animals and plants (T63). 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 T63.422A: its own notes plus those printed at T63.4, T63, block T51-T65, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- bite or touch of venomous animal
- pricked or stuck by thorn or leaf
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- 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, if applicable, for anaphylactic shock (T78.2)
- 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 T63
- Ainitial encounter this code
- Dsubsequent encounter
- Ssequela
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name T63.422A, its category, or a range that includes it.
Excludes1 5
These codes carry an Excludes1 note naming T63.422A: they are not reported together with it, unless the two conditions are unrelated.
- Block T07 Injuries involving multiple body regionsinsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block W50-W64 Exposure to animate mechanical forcesToxic effect of contact with venomous animals and plants (T63.-) names T63.-, which includes this code
- W56 Contact with nonvenomous marine animalcontact with venomous marine animal (T63.-) names T63.-, which includes this code
- W57 Bitten or stung by nonvenomous insect and other nonvenomous arthropodscontact with venomous insects and arthropods (T63.2-, T63.3-, T63.4-) names T63.4-, which includes this code
- W64 Exposure to other animate mechanical forcescontact with venomous animal (T63.-) names T63.-, which includes this code
Excludes2 11
These codes carry an Excludes2 note naming T63.422A: its condition is not part of those codes, and both may be reported when the patient has both.
- Block S00-S09 Injuries to the headinsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S10-S19 Injuries to the neckinsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S20-S29 Injuries to the thoraxinsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S30-S39 Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitalsinsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S40-S49 Injuries to the shoulder and upper arminsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S50-S59 Injuries to the elbow and forearminsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S60-S69 Injuries to the wrist, hand and fingersinsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S70-S79 Injuries to the hip and thighvenomous insect bite or sting (T63.4-) names T63.4-, which includes this code
- S71 Open wound of hip and thighbite of venomous animal (T63.-) names T63.-, which includes this code
- Block S80-S89 Injuries to the knee and lower leginsect bite or sting, venomous (T63.4) names T63.4, which includes this code
- Block S90-S99 Injuries to the ankle and footinsect bite or sting, venomous (T63.4) names T63.4, 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.
Patient EducationClinical
Insect Bites and Stings
Most insect bites are harmless, though they sometimes cause discomfort. Bee, wasp, and hornet stings and fire ant bites usually hurt. Mosquito and flea bites usually itch. Insects can also spread diseases. In the United States, some mosquitoes spread West Nile virus.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T63.422A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T63.422AOverview
Is T63.422A (Toxic effect of venom of ants, intentional self-harm) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of venom of ants, intentional self-harm, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in T63.422A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for toxic effect of venom of ants, intentional self-harm, such as an emergency visit or first evaluation.
What MS-DRG does T63.422A group to?
When toxic effect of venom of ants, intentional self-harm, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 918, 917, with relative weights from 0.8716 to 1.5698 depending on complications. Higher weights mean higher Medicare reimbursement.
Can T63.422A be reported with a code from Z77?
Not as a rule. The Excludes1 note at block T51-T65, which applies to T63.422A, lists "contact with and (suspected) exposure to toxic substances (Z77.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
Does T63.422A need an additional code?
When the condition applies, yes. The Use Additional Code note at T63.4, which applies to T63.422A, reads: code, if applicable, for anaphylactic shock (T78.2). The additional code is reported after T63.422A.
What HCC is T63.422A?
T63.422A (toxic effect of venom of ants, intentional self-harm, initial encounter) maps to CMS-HCC Category 155 (Major Depression, Moderate or Severe, without Psychosis), commonly written as HCC 155, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 59 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 132.
Does T63.422A risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, T63.422A adds a risk adjustment factor of about 0.299 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.108 to 0.316 depending on the payment segment). A more severe related category (HCC 151, HCC 152, HCC 153, and HCC 154) supersedes it when both are reported. See the full factor table on the HCC 155 category page.
