2027 ICD-10-CM Diagnosis Code S80.229ABlister (nonthermal), unspecified knee, initial encounter

ICD-10-CM Codes›S00–T88›S80-S89›S80

ICD-10-CM S80.229A
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

S80.229A is a billable ICD-10-CM diagnosis code for blister (nonthermal), unspecified knee, 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 606 through 607, 963 through 965. Coders also document this condition as traumatic blister of knee. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Superficial injury; contusion, initial encounter.

Code Identity

ICD-10-CM Code
S80.229A
Billable Status
Yes — Valid for Submission
Code Describes
Blister (nonthermal), unspecified knee, initial encounter
Short Description
Blister (nonthermal), unspecified knee, initial encounter
Same as the full description in the CMS dataset.
Parent Code
S80.229
Blister (nonthermal), unspecified knee

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionS80-S89Injuries to the knee and lower leg
CategoryS80Superficial injury of knee and lower leg
This CodeS80.229ABlister (nonthermal), unspecified knee, initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Traumatic blister of knee
  • Traumatic blister of knee, infected

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Superficial injury of knee and lower leg (S80). 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 S80.229A: its own notes plus those printed at S80, block S80-S89, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.

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 S80 Superficial injury of knee and lower leg applies to 144 codes
  • superficial injury of ankle and foot (S90.-)
From Block S80-S89 Injuries to the knee and lower leg applies to 4,680 codes
  • burns and corrosions (T20-T32)
  • frostbite (T33-T34)
  • injuries of ankle and foot, except fracture of ankle and malleolus (S90-S99)
  • insect bite or sting, venomous (T63.4)
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 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 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 S80 Superficial injury of knee and lower leg applies to 144 codes
  • The appropriate 7th character is to be added to each code from category S80
Values for category S80 Encounter: Initial, Subsequent, Sequela
  • Ainitial encounter this code
  • Dsubsequent encounter
  • Ssequela

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

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INJ017
Superficial injury; contusion, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Blister

    visible accumulations of fluid within or beneath the epidermis.

Patient EducationClinical

Blisters

Blisters are fluid-filled sacs on the outer layer of your skin. They form because of rubbing, heat, or diseases of the skin. They are most common on your hands and feet.

The full article covers:

  • What are blisters?
  • What causes blisters?
  • What are the treatments for blisters?
  • Can blisters be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert S80.229A to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
916.2 Blister hip & leg
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About S80.229AOverview

What is the ICD-10 code for blister (nonthermal), unspecified knee, initial encounter?

The ICD-10-CM code for blister (nonthermal), unspecified knee, initial encounter is S80.229A (sometimes written as S80229A). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is S80.229A (Blister (nonthermal), unspecified knee) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report blister (nonthermal), unspecified knee, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What does the 7th character A in S80.229A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for blister (nonthermal), unspecified knee, such as an emergency visit or first evaluation.

What MS-DRG does S80.229A group to?

When blister (nonthermal), unspecified knee, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 964, 965, 607, 963, 606, with relative weights from 0.8772 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of S80.229A?

Under the General Equivalence Mappings, blister (nonthermal), unspecified knee, initial encounter converts to ICD-9-CM 916.2 (blister hip & leg). The mapping is approximate, so confirm the match fits the documentation.