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S31.65AA ICD-10-CM Code: Open bite of abdominal wall, unspecified flank with penetration into peritoneal cavity, initial encounter

Compare with another code for S31.65AACheck this code on a claim

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

7th character
Required — see the character table on this page
Tabular directives
7 inclusion terms · 2 Excludes1 · 8 Excludes2 · 3 code-also instructions

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too, and is marked with where it comes from.

7th character:A· The appropriate 7th character is to be added to each code from category S31All 7th characters

Excludes1Not reported with this code unless documented as unrelated
  • superficial bite of abdominal wall (S30.861, S30.871) (from S31.65)
  • traumatic amputation of part of abdomen, lower back and pelvis (S38.2-, S38.3) (from S31)
Code alsofrom S31May be needed with this code
Excludes2Not included here; may be reported together
  • open wound of hip (S71.00-S71.02) (from S31)
  • open fracture of pelvis (S32.1--S32.9 with 7th character B) (from S31)
  • burns and corrosions (T20-T32) (from S30-S39)
  • effects of foreign body in anus and rectum (T18.5) (from S30-S39)

+4 more in Instructions

IncludesWhat this code covers
  • injuries to the abdominal wall (from S30-S39)
  • injuries to the anus (from S30-S39)
  • injuries to the buttock (from S30-S39)
  • injuries to the external genitalia (from S30-S39)

+3 more in Instructions

Where it sits Source: CMS/NCHS

Under:Chapter 19: Injury, Poisoning and Certain Other Consequences of External CausesS30-S39 Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitalsS31 Open wound of abdomen, lower back, pelvis and external genitalsS31.6 Open wound of abdominal wall with penetration into peritoneal cavityS31.65 Open bite of abdominal wall with penetration into peritoneal cavityS31.65A Open bite of abdominal wall, unspecified flank with penetration into peritoneal cavity

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

  • MS-DRG 393 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH MCC (MDC 06)
  • MS-DRG 394 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITH CC (MDC 06)
  • MS-DRG 395 — OTHER DIGESTIVE SYSTEM DIAGNOSES WITHOUT CC/MCC (MDC 06)
  • MS-DRG 963 — OTHER MULTIPLE SIGNIFICANT TRAUMA WITH MCC (MDC 24)
  • MS-DRG 964 — OTHER MULTIPLE SIGNIFICANT TRAUMA WITH CC (MDC 24)
  • MS-DRG 965 — OTHER MULTIPLE SIGNIFICANT TRAUMA WITHOUT CC/MCC (MDC 24)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for S31.65AA in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on S31.65AA itself; “inherited from” names the category or block whose note applies here.

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • injuries to the abdominal wall
  • injuries to the anus
  • injuries to the buttock
  • injuries to the external genitalia
  • injuries to the flank
  • injuries to the groin

Source: inherited from S30-S39

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Open bite of abdominal wall, flank NOS, with penetration into peritoneal cavity

Source: inherited from S31.65A

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Code Also

Additional codes that may be required to fully describe the encounter.

Source: inherited from S31

7th Character Guide

"The appropriate 7th character is to be added to each code from category S31"

  • A — initial encounter (this page’s code)
  • D — subsequent encounter
  • S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

S31.65AA, S31.65AD, S31.65AS

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for S31.65AA

MedCoder structured workflow — derived from this code’s own official record

Before you code S31.65AA

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, S31.65AA may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by the presence or absence of the associated condition, open versus closed. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewS31.654A, S31.655A, S31.656A, S31.657A

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. This page’s code carries “A”. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

    See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

  3. Laterality is coded in this family. Confirm the side documented — right, left, or bilateral — and select the matching code (this page’s code: unspecified). The unspecified-side code applies only when the record states no side. Laterality is assigned from the documented side; where a bilateral code exists and both sides are documented, it is used instead of two unilateral codes (Guidelines I.B.13).

    ReviewS31.656A · right, S31.657A · left

    Guide: Laterality coding →

  4. S31.65AA’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).

    Guide: Combination codes →

  5. Confirm the injury type, the anatomical site at the most specific level documented, laterality where the family codes it, and the encounter for the 7th character. Each injury is coded separately unless the classification provides a combination code, and a superficial injury is not coded when a more severe injury of the same site is documented. Injury chapter guidelines (Guidelines I.C.19.b, I.C.19.b.1).

    Guide: 7th characters: initial, subsequent, sequela →

  6. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with S31.65AA. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — S31.65AA is appropriate when the documentation goes no further.

    ReviewS31.654A, S31.655A, S31.656A, S31.657A

  2. Does the documentation support a condition named in S31.65AA’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewS30.861, S30.871, S38.2, S38.3

  3. Is the side documented?
    Yes → Select the code for the documented side (or the bilateral code when both sides are documented and one exists).
    No → Use the unspecified-side code only when the record states no side; a query is the alternative.

    ReviewS31.656A · right, S31.657A · left

  4. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
    Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
    No → The code is invalid without its 7th character — query for the missing element.

Consider S31.65AA. Then review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
Anatomical site
At the most specific level the record states; a site the classification separates cannot be assumed from a procedure or a measurement.
Laterality
Right, left or bilateral as documented; unspecified only when the record states no side (Guidelines I.B.13).
Encounter type
Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).
The associated condition or complication
Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).
Open or closed; displaced or nondisplaced
Defaults apply when the record is silent: closed, and displaced (Guidelines I.C.19.c).
External cause, place and activity
For the external cause codes reported with the injury or poisoning, where documented (Guidelines I.C.20.a).
Any detail beyond this code’s title
What the record states that a more specific code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting S31.65AA(2 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with S31.65AA: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareS30.861, S30.871, S38.2, S38.3

    See the official tabular notes · Guidelines I.A.12.a

  • Excludes2 — not part of S31.65AA(8 notes)

    Coding workflow: The conditions named in this note are not included in S31.65AA. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareS32.1, S32.9, T18.5, T19, T63.4

    See the official tabular notes · Guidelines I.A.12.b

  • Code Also — related condition(3 notes)

    Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

    ReviewS24.0, S24.1, S34.0, S34.1

    See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewS31.654A, S31.655A, S31.656A, S31.657A

Documentation: Both the condition S31.65AA describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewS30.861, S30.871, S38.2, S38.3

Documentation: The patient returns during the healing or recovery phase after active treatment of the same condition.

Coding question: Which 7th character applies?

Path: Review the official 7th-character definitions for this family in the 7th Character Guide.

Reason: “Initial encounter” means active treatment, not the first visit; care during recovery takes “subsequent encounter”, and a complication arising from the original condition takes “sequela” (Guidelines I.C.19.a).

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse S31.65AA with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of S31.65AA — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • S30.861— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of superficial bite of abdominal wall moves the case to S30.861; the two are not reported together unless documented as unrelated.

    Full comparison: S31.65AA vs S30.861 →

  • S30.871— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of superficial bite of abdominal wall moves the case to S30.871; the two are not reported together unless documented as unrelated.

    Full comparison: S31.65AA vs S30.871 →

  • S38.2— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of traumatic amputation of part of abdomen, lower back and pelvis moves the case to S38.2; the two are not reported together unless documented as unrelated.

    Full comparison: S31.65AA vs S38.2 →

  • S38.3— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of traumatic amputation of part of abdomen, lower back and pelvis moves the case to S38.3; the two are not reported together unless documented as unrelated.

    Full comparison: S31.65AA vs S38.3 →

  • S31.656A— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition with a different side named (the opposite side, both sides, or none); the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented right side moves the case to S31.656A.

    Full comparison: S31.65AA vs S31.656A →

  • S31.657A— Laterality relationship (Review)

    Same condition; these differ only in which side is documented.

    The same condition with a different side named (the opposite side, both sides, or none); the documented side decides, and a bilateral code, where one exists, replaces the pair when both sides are documented.

    What moves you there: A documented left side moves the case to S31.657A.

    Full comparison: S31.65AA vs S31.657A →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Open bite of abdominal wall, unspecified flank with penetration into peritoneal cavity, initial encounter is a billable ICD-10-CM diagnosis code (S31.65AA).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. A 7th character applies in this family. Confirm the documented encounter matches the character assigned. See the official 7th-character definitions and this code’s variants
  2. 3 Code Also notes — a second code may apply; the guidelines leave its sequencing to the circumstances of the encounter. See the Code Also notes
  3. 2 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  4. 8 Excludes2 entries — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

  • MCC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name S31.65AA or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes2 note: S31.1 — Open wound of abdominal wall without penetration into peritoneal cavity (via S31.6.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 1 Use Additional Code instruction: S38.1 — Crushing injury of abdomen, lower back, and pelvis (via S31.-).

These codes instruct coders to additionally report this code when it applies.

Referenced by 5 Code Also instructions: S34 — Injury of lumbar and sacral spinal cord and nerves at abdomen, lower back and pelvis level (via S31.-), S35 — Injury of blood vessels at abdomen, lower back and pelvis level (via S31.-), S36 — Injury of intra-abdominal organs (via S31.-), S37 — Injury of urinary and pelvic organs (via S31.-), S39 — Other and unspecified injuries of abdomen, lower back, pelvis and external genitals (via S31.-).

These codes suggest coding this condition alongside when both are present.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: MCC — Major Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 160 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 957-959 (Other O.R. Procedures for Multiple Significant Trauma); DRGs 963-965 (Other Multiple Significant Trauma).

Named in the grouper logic of 6 MS-DRGs: DRG 393 (MDC 06), DRG 394 (MDC 06), DRG 395 (MDC 06), DRG 963 (MDC 24), DRG 964 (MDC 24), DRG 965 (MDC 24).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INJ013 — Open wounds of trunk, initial encounter (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as MCC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

S31.64AA — Puncture wound of abdominal wall with foreign body, unspecified flank with penetration into peritoneal cavity, initial encounter, S31.650A — Open bite of abdominal wall, right upper quadrant with penetration into peritoneal cavity, initial encounter, S31.651A — Open bite of abdominal wall, left upper quadrant with penetration into peritoneal cavity, initial encounter, S31.652A — Open bite of abdominal wall, epigastric region with penetration into peritoneal cavity, initial encounter, S31.653A — Open bite of abdominal wall, right lower quadrant with penetration into peritoneal cavity, initial encounter, S31.654A — Open bite of abdominal wall, left lower quadrant with penetration into peritoneal cavity, initial encounter, S31.655A — Open bite of abdominal wall, periumbilic region with penetration into peritoneal cavity, initial encounter, S31.656A — Open bite of abdominal wall, right flank with penetration into peritoneal cavity, initial encounter, S31.657A — Open bite of abdominal wall, left flank with penetration into peritoneal cavity, initial encounter, S31.659A — Open bite of abdominal wall, unspecified quadrant with penetration into peritoneal cavity, initial encounter, S31.831A — Laceration without foreign body of anus, initial encounter, S31.832A — Laceration with foreign body of anus, initial encounter, S31.833A — Puncture wound without foreign body of anus, initial encounter, S31.834A — Puncture wound with foreign body of anus, initial encounter, S31.835A — Open bite of anus, initial encounter, S31.839A — Unspecified open wound of anus, initial encounter, S36.81XA — Injury of peritoneum, initial encounter, S36.892A — Contusion of other intra-abdominal organs, initial encounter, S36.893A — Laceration of other intra-abdominal organs, initial encounter, S36.898A — Other injury of other intra-abdominal organs, initial encounter, +139 more

Same condition, different side

Same title, differing only in which side of the body it names: right, left, bilateral or unspecified.

S31.656A — Open bite of abdominal wall, right flank with penetration into peritoneal cavity, initial encounter (right)Compare S31.65AA vs S31.656A →, S31.657A — Open bite of abdominal wall, left flank with penetration into peritoneal cavity, initial encounter (left)Compare S31.65AA vs S31.657A →

Same injury, other encounter phase

Same injury, coded at a different phase of treatment via the 7th character.

S31.65AD — Open bite of abdominal wall, unspecified flank with penetration into peritoneal cavity, subsequent encounterCompare S31.65AA vs S31.65AD →, S31.65AS — Open bite of abdominal wall, unspecified flank with penetration into peritoneal cavity, sequelaCompare S31.65AA vs S31.65AS →

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Open wounds of trunk, initial encounter).

S31.64AA — Puncture wound of abdominal wall with foreign body, unspecified flank with penetration into peritoneal cavity, initial encounter, S31.650A — Open bite of abdominal wall, right upper quadrant with penetration into peritoneal cavity, initial encounter, S31.651A — Open bite of abdominal wall, left upper quadrant with penetration into peritoneal cavity, initial encounter, S31.652A — Open bite of abdominal wall, epigastric region with penetration into peritoneal cavity, initial encounter, S31.653A — Open bite of abdominal wall, right lower quadrant with penetration into peritoneal cavity, initial encounter, S31.654A — Open bite of abdominal wall, left lower quadrant with penetration into peritoneal cavity, initial encounter, S31.655A — Open bite of abdominal wall, periumbilic region with penetration into peritoneal cavity, initial encounter, S31.656A — Open bite of abdominal wall, right flank with penetration into peritoneal cavity, initial encounter, S31.657A — Open bite of abdominal wall, left flank with penetration into peritoneal cavity, initial encounter, S31.659A — Open bite of abdominal wall, unspecified quadrant with penetration into peritoneal cavity, initial encounter, S31.801A — Laceration without foreign body of unspecified buttock, initial encounter, S31.802A — Laceration with foreign body of unspecified buttock, initial encounter, S31.803A — Puncture wound without foreign body of unspecified buttock, initial encounter, S31.804A — Puncture wound with foreign body of unspecified buttock, initial encounter, S31.805A — Open bite of unspecified buttock, initial encounter, S31.809A — Unspecified open wound of unspecified buttock, initial encounter, S31.811A — Laceration without foreign body of right buttock, initial encounter, S31.812A — Laceration with foreign body of right buttock, initial encounter, S31.813A — Puncture wound without foreign body of right buttock, initial encounter, S31.814A — Puncture wound with foreign body of right buttock, initial encounter, +267 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of S31.65AA in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run S31.65AA with these 7 related codes in Claim Check

Hierarchy

Referenced by Excludes2 notes

Referenced by Use Additional Code instructions

Referenced by Code Also instructions

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 06 — Diseases and Disorders of the Digestive System[MDC crossing]: “Diseases and Disorders of the Digestive System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 5,748 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027
  • MDC 24 — Multiple Significant Trauma[MDC crossing]: “Multiple Significant Trauma — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 22,991 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Nearest codes (40)

Change history

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Does S31.65AA require a 7th character?

Yes. The appropriate 7th character is to be added to each code from category S31.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "S31.65AA — Open bite of abdominal wall, unspecified flank with penetration into peritoneal cavity, initial encounter." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/s31.65aa-open-bite-of-abdominal-wall-unspecified-flank-with-penetration-into-peritoneal-cavity-initial-encounter

Change history

  • FY2026 — October 1, 2025
    Added to the code set
    Open bite of abdominal wall, unspecified flank with penetration into peritoneal cavity, initial encounter
    FY2026 changes

Nearest Codes in This Family

Official ICD-10-CM classifications closest to S31.65AA in its code family, with their registry titles.

View all codes in the S31 family