2026 ICD-10-CM Diagnosis Code S01.551AOpen bite of lip, initial encounter
S01.551A is a billable ICD-10-CM diagnosis code for open bite of lip, 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 157 through 159, 963 through 965. Coders also document this condition as dog bite of face. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Any dental condition including traumatic injury; and Open wounds of head and neck, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Dog bite of face
- Dog bite of mouth
- Open wound of face due to animal bite
- Open wound of face due to bite
- Open wound of face due to dog bite
- Open wound of lip due to dog bite
- Open wound of lip due to human bite
- Open wound of mouth due to bite
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Open wound of head (S01). 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.
Patient EducationClinical
Animal Bites
Wild animals usually avoid people. They might attack, however, if they feel threatened, are sick, or are protecting their young or territory. Attacks by pets are more common. Animal bites rarely are life-threatening, but if they become infected, you can develop serious medical problems.
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Convert S01.551A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S01.551AOverview
Is S01.551A (Open bite of lip) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report open bite of lip, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in S01.551A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for open bite of lip, such as an emergency visit or first evaluation.
What MS-DRG does S01.551A group to?
When open bite of lip, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 157, 158, 159, 963, 964, 965, with relative weights from 0.7085 to 2.7338 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S01.551A?
Under the General Equivalence Mappings, open bite of lip, initial encounter converts to ICD-9-CM 873.43 (open wound of lip). 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.
