ICD-10 Code S31.627A: Open bite of left flank wall, initial encounter

Key Takeaways

ICD-10 Code S31.627A describes an open bite of the left flank wall without penetration into the peritoneal cavity, initial encounter.

S31.627 (without a 7th character) is non-billable; you must append A, D, or S to submit a valid claim.

Documentation must confirm laterality (left), wound type (open bite), absence of peritoneal penetration, and encounter type before using this code.

Pabau’s claims management software supports structured clinical documentation workflows that reduce coding errors on open wound encounters.

Open wound coding in the S31 family trips up even experienced coders. The parent code S31.627 looks complete, but submitting it on a claim guarantees a rejection: it is non-billable without a 7th character. ICD-10 Code S31.627A resolves that by adding the initial encounter qualifier, making it the correct code for the first active treatment visit for an open bite of the left flank wall without peritoneal penetration. This reference page covers the full descriptor, all three 7th character options, billable status, code hierarchy, related codes, documentation requirements, and common coding guidelines for S31.627A.

Accurate ICD-10-CM diagnosis coding for traumatic wounds requires laterality, wound type specificity, and encounter type – all three are embedded in S31.627A. The sections below walk through each component systematically.

ICD-10 Code S31.627A: code description and full descriptor

S31.627A carries the official descriptor: Open bite of left flank wall without penetration into peritoneal cavity, initial encounter. Every word in that descriptor is clinically and administratively meaningful.

The code is verified as billable by the CDC/NCHS ICD-10-CM lookup tool and is accepted on both professional and institutional claim forms. Pabau’s claims management software supports structured documentation workflows that help reduce coding errors on open wound encounters like this one.

7th character extensions: S31.627A, S31.627D, and S31.627S

S31.627 requires a 7th character to become billable. Three options exist, each denoting a distinct phase of care. Selecting the wrong one is one of the most common reasons open wound claims are denied.

The ICD-10-CM Official Guidelines for Coding and Reporting define “initial encounter” as any visit during which the patient is receiving active treatment for the condition – not necessarily the first visit chronologically. A patient seen at a second facility for wound management of the same open bite injury would still qualify for the A suffix if active treatment is ongoing.

Sequela coding (S) works differently: the sequela code is listed first, with the injury code appended using the S suffix to identify the original cause. Always confirm the encounter context in the medical record before assigning the 7th character. The CMS ICD-10 codes page provides the annual update files and official coding guidance to support accurate 7th character selection.

What is an open bite of the left flank wall?

An open bite wound results from teeth penetrating the skin and soft tissue, leaving a breach in the skin surface. The distinction between “open bite” and other wound types in the S31.6 family matters for both clinical management and code selection.

• Open bite (S31.627A): Wound caused by animal or human teeth; classified separately from lacerations, punctures, and abrasions in ICD-10-CM.
• Left flank wall: The lateral aspect of the left abdominal region, below the costal margin and above the iliac crest; the “flank” describes the area between the ribs and the hip on the body’s left side.
• Without penetration into peritoneal cavity: The wound does not breach the peritoneal membrane; structures within the abdominal cavity are not exposed. This is a critical clinical and coding distinction from S31.621A (open bite of abdominal wall with penetration into peritoneal cavity, left side).
• Initial encounter: Active treatment is being rendered for this injury during the visit being coded.

Bite wounds of the abdominal flank commonly present in emergency and urgent care settings following animal attacks or altercations. Clinicians should document wound depth, contamination status, and the absence of peritoneal signs in the medical record to substantiate the non-penetrating classification. Thorough medical record documentation standards are essential when coding wounds of this nature.

Billable status and claim submission for ICD-10 Code S31.627A

S31.627A is a billable ICD-10-CM code. The parent code S31.627 is not billable on its own; it requires a 7th character extension. Once the A, D, or S suffix is appended, the resulting code is valid for submission.

• Valid for submission on CMS-1500 (professional claims, used by physician offices and outpatient providers)
• Valid for submission on UB-04 (institutional claims, used by hospitals and facility billing)
• Accepted across commercial payers, Medicare, and Medicaid billing systems
• Confirm current payer-specific policies independently, as coverage guidelines can vary by plan and provider contract

When submitting open wound claims, coders should ensure the diagnosis code aligns with any associated procedure codes for wound care, irrigation, or closure. Maintaining HIPAA-compliant medical documentation for every encounter supports audit readiness and reduces claim denial risk. Practices managing high volumes of injury coding benefit from structured claims management software that flags missing 7th character extensions before submission.

Code hierarchy: S31.627A within the S31 family

Understanding where S31.627A sits in the ICD-10-CM hierarchy helps coders navigate related codes and verify correct code selection. The hierarchy from chapter level down to the billable code is:

The WHO ICD-10 browser provides the international classification hierarchy. The US-specific ICD-10-CM clinical modification adds the 7th character layer and the granular laterality coding (left vs right flank) not present in the base WHO system. For traumatic injury coding references across other anatomical sites, the same S00-T88 chapter applies.

Related codes in the S31.6 family

S31.627A is one code within a structured family covering different wound types and laterality options. Choosing the correct sibling code requires careful reading of the medical record for wound characteristics.

The most consequential distinction is between S31.627A (without peritoneal penetration) and S31.617A (with penetration). These represent fundamentally different injuries with different clinical management paths. The medical record must contain explicit documentation of wound depth and examination findings before the coder selects between these two codes. Use the AAPC Codify ICD-10-CM lookup to cross-reference descriptors when reviewing the full S31.6 code family.

Reduce coding errors on open wound encounters

Pabau helps clinical teams document wound characteristics, encounter types, and laterality at the point of care, giving coders the complete record they need to assign codes like ICD-10 Code S31.627A accurately and submit clean claims the first time.

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Documentation requirements for ICD-10 Code S31.627A

Using S31.627A requires the medical record to support every element of the code descriptor. Missing documentation for any component is grounds for a coding query or claim denial.

• Wound type (open bite): The clinician’s note must identify the wound as a bite wound. Generic terms like “open wound” or “laceration” do not support this code. Look for language such as “animal bite,” “human bite,” or “bite wound” in the assessment.
• Laterality (left): The record must specify the left flank or left lateral abdominal wall. “Flank wound” without laterality directs the coder to S31.629A (unspecified site) instead.
• Absence of peritoneal penetration: The examiner’s findings must document that the wound does not penetrate into the peritoneal cavity. Physical exam notes, wound exploration findings, or imaging results (where obtained) should support this conclusion.
• Encounter type (initial): The visit must constitute active treatment. A follow-up visit for wound check during healing uses S31.627D; a visit addressing scarring after the wound has healed uses S31.627S.

Maintaining structured clinical record-keeping that captures wound characteristics at the time of examination reduces the need for provider queries and supports faster claim adjudication. Practices that use digital intake and clinical forms can embed prompts for laterality, wound type, and depth documentation directly into the encounter workflow. For broader accurate ICD-10-CM diagnosis coding practices, laterality and encounter-type specificity apply consistently across the classification system.

Coding guidelines and clinical notes

The ICD-10-CM Official Guidelines for Coding and Reporting govern how S31.627A is applied in practice. Key guidelines applicable to this code include:

• Open bite definition (ICD-10-CM guideline): ICD-10-CM classifies open bites as a distinct wound type separate from lacerations, punctures, and contusions. Do not substitute a laceration code when the wound mechanism is a bite.
• Coding active treatment: Per Section II of the ICD-10-CM Official Guidelines, “initial encounter” applies while the patient is receiving active treatment regardless of whether the provider is seeing the patient for the first time.
• Excludes notes: ICD-10-CM includes guidance to exclude bite of abdominal wall involving the external genitalia (covered under separate codes in S31.0-S31.5). Confirm the anatomical site is confined to the flank wall before using S31.627A.
• Sequencing: For an emergency department or outpatient visit, the open wound code is sequenced as the principal diagnosis when it is the reason for the encounter. External cause codes from the V00-Y99 chapter should be added as secondary diagnoses to capture the mechanism (e.g. W54 for dog bite, W50 for bite/struck by another person).
• Multiple wound coding: If the patient presents with wounds at multiple sites, each billable open wound code is reported separately. Do not use a combination code or unspecified site code when specific bilateral or multi-site wounds are documented.

Maintaining familiarity with ICD-10-CM diagnostic coding practice across categories helps coders apply consistent logic to 7th character selection, sequencing, and excludes notes. For clinic teams managing ongoing clinic software compliance requirements, integrating coding accuracy into documentation workflows reduces downstream audit exposure.

Conclusion

Open bite claims in the S31 family fail most often because of a missing 7th character or undocumented laterality. ICD-10 Code S31.627A resolves both issues when the medical record contains specific documentation of a left flank bite wound without peritoneal penetration during an initial active treatment encounter.

Pabau’s compliance management tools and structured clinical documentation workflows help practices capture the wound specificity, laterality, and encounter context that coders need to assign S31.627A and related codes accurately. To see how Pabau supports injury coding workflows, book a demo.

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