2027 ICD-10-CM Diagnosis Code S99.821AOther specified injuries of right foot, initial encounter
S99.821A is a billable ICD-10-CM diagnosis code for other specified injuries of right foot, 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 913 through 914, 963 through 965. Coders also document this condition as calcaneal petechiae. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified injury.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Calcaneal petechiae
- Calcaneal petechiae of right foot
- Foreign body in heel
- Foreign body of right heel
- Petechiae
- Petechiae of skin
- Traumatic petechiae
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Other and unspecified injuries of ankle and foot (S99). 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 S99.821A: its own notes plus those printed at S99.8, block S90-S99, 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.
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.
- 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 subcategory S99.8
- 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 S99.821A, its category, or a range that includes it.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Foot Injuries and Disorders
Each of your feet has 26 bones, 33 joints, and more than 100 tendons, muscles, and ligaments. No wonder a lot of things can go wrong. Here are a few common problems:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S99.821A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S99.821AOverview
What is the ICD-10 code for other specified injuries of right foot, initial encounter?
The ICD-10-CM code for other specified injuries of right foot, initial encounter is S99.821A (sometimes written as S99821A). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is S99.821A (Other specified injuries of right foot) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other specified injuries of right foot, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in S99.821A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for other specified injuries of right foot, such as an emergency visit or first evaluation.
What MS-DRG does S99.821A group to?
When other specified injuries of right foot, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 964, 965, 914, 913, 963, with relative weights from 0.9281 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S99.821A?
Under the General Equivalence Mappings, other specified injuries of right foot, initial encounter converts to ICD-9-CM 959.7 (lower leg injury NOS). The mapping is approximate, so confirm the match fits the documentation.
