S01.551 vs S01.551A
S01.551 (Open bite of lip) compared with S01.551A (Open bite of lip, initial encounter), from the official CMS tabular data.
Summary
These codes represent different levels of the same hierarchy: S01.551 is the non-billable header that contains S01.551A, so only S01.551A (or a sibling) is reported.
Registry fact- What is different?
Title wording and billing status.S01.551A’s title adds “initial encounter” to the wording the two share (“Open bite of lip”). S01.551 is a non-billable header; S01.551A is billable.
Registry fact
- Can these codes be reported together?
Not as a pair.S01.551 is the non-billable header that contains S01.551A. A header is not reported on a claim, so the choice is S01.551A or a sibling that matches the documentation.
Registry fact
- Is there an Excludes1 relationship?
None.Neither entry carries an Excludes1 note that names the other code. S01.551 carries 2 Excludes1 notes and S01.551A carries 2 Excludes1 notes covering other codes; the side-by-side table quotes them.
Official rule
- Is there an Excludes2 relationship?
None.Neither entry carries an Excludes2 note that names the other code. S01.551 carries 13 Excludes2 notes and S01.551A carries 13 Excludes2 notes covering other codes; the side-by-side table quotes them.
Official rule
- Is one more specific?
Yes.S01.551A is a subdivision of S01.551 in the tabular hierarchy, so it is the more specific of the two.
Registry fact
- Is one a parent or header code?
Yes.S01.551 is the non-billable header that contains S01.551A. A header stands for the whole family beneath it and is not reported on a claim.
Registry fact
- Are there sequencing instructions?
None.Neither entry carries a Code First or Use Additional Code note that names the other.
Official rule
- Are there other coding relationships?
None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.
MedCoder-derived
Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels
Can these codes be reported together?
Not as a pair — S01.551 is not reportable. S01.551 is the non-billable category that contains S01.551A.
A header stands for the whole family of codes beneath it and is not reported on a claim, so the choice is S01.551A or a sibling that matches the documentation. No Excludes1/Excludes2 relationship exists between these codes in the official tabular list.
Official guidance behind these answers
Section I.B.2 — Level of Detail in Coding · applies to: S01.551 and S01.551A
Diagnosis codes are to be used and reported at their highest number of characters available and to the highest level of specificity documented in the medical record. ICD-10-CM diagnosis codes are composed of codes with 3, 4, 5, 6 or 7 characters. Codes with three characters are included in ICD-10-CM as the heading of a category of codes that may be further subdivided by the use of fourth and/or fifth characters and/or sixth characters, which provide greater detail. A three-character code is to be used only if it is not further subdivided. A code is invalid if it has not been coded to the full number of characters required for that code, including the 7th character, if applicable.
ICD-10-CM Official Guidelines FY2026
Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum
Side by side
| S01.551Open bite of lip | S01.551AOpen bite of lip, initial encounter | |
|---|---|---|
| Billing status | Non-billable header | Billable |
| Classification | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) | S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88) |
| Definition | Open bite of lip is a non-billable ICD-10-CM category code (S01.551). | Open bite of lip, initial encounter is a billable ICD-10-CM diagnosis code (S01.551A). |
| 7th character | The appropriate 7th character is to be added to each code from category S01 | The appropriate 7th character is to be added to each code from category S01 |
| Includes | injuries of ear injuries of eye injuries of face [any part] injuries of gum | injuries of ear injuries of eye injuries of face [any part] injuries of gum |
| Excludes1 | superficial bite of lip (S00.571) open skull fracture (S02.- with 7th character B) | superficial bite of lip (S00.571) open skull fracture (S02.- with 7th character B) |
| Excludes2 | tooth dislocation (S03.2) tooth fracture (S02.5) injury of eye and orbit (S05.-) traumatic amputation of part of head (S08.-) burns and corrosions (T20-T32) effects of foreign body in ear (T16) effects of foreign body in larynx (T17.3) effects of foreign body in mouth NOS (T18.0) effects of foreign body in nose (T17.0-T17.1) effects of foreign body in pharynx (T17.2) effects of foreign body on external eye (T15.-) frostbite (T33-T34) insect bite or sting, venomous (T63.4) | tooth dislocation (S03.2) tooth fracture (S02.5) injury of eye and orbit (S05.-) traumatic amputation of part of head (S08.-) burns and corrosions (T20-T32) effects of foreign body in ear (T16) effects of foreign body in larynx (T17.3) effects of foreign body in mouth NOS (T18.0) effects of foreign body in nose (T17.0-T17.1) effects of foreign body in pharynx (T17.2) effects of foreign body on external eye (T15.-) frostbite (T33-T34) insect bite or sting, venomous (T63.4) |
| Code also | any associated: injury of cranial nerve (S04.-) injury of muscle and tendon of head (S09.1-) intracranial injury (S06.-) wound infection for any associated infection | any associated: injury of cranial nerve (S04.-) injury of muscle and tendon of head (S09.1-) intracranial injury (S06.-) wound infection for any associated infection |
Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.
Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources