ICD-10 Code S31.607S: Abdominal wall open wound sequela

Key takeaways

ICD-10 Code S31.607S describes an unspecified open wound of the abdominal wall, left flank, with penetration into the peritoneal cavity, sequela (late effect).

S31.607S is billable and specific. The parent code S31.607 without a 7th character is not billable and cannot be submitted for reimbursement.

The 7th character S denotes sequela, meaning the wound has healed but a late effect persists. Confusing S with D (subsequent encounter) is a common denial trigger.

Pabau’s claims management software helps trauma and surgical practices document peritoneal wound sequelae accurately and submit cleaner claims.

ICD-10 Code S31.607S is a billable, specific ICD-10-CM diagnosis code. It covers an unspecified open wound of the abdominal wall, left flank, with penetration into the peritoneal cavity, sequela.

Coders and clinicians use this code when a patient presents with a late effect of a prior penetrating abdominal wound. It does not apply to an active or ongoing wound encounter.

The 2026 ICD-10-CM edition made this code effective October 1, 2025. It sits within the S30-S39 injury block covering injuries to the abdomen, lower back, lumbar spine, pelvis, and external genitalia. Thoracic trauma follows the same 7th character convention, as in ICD-10 code S23.131S.

What S31.607S means: Breaking down the code structure

Each segment of S31.607S encodes a distinct clinical fact. Misreading any segment leads to the wrong code selection and a potential denial. Here is what each character represents:

• S: The chapter prefix, indicating an injury code (Chapter 19 of ICD-10-CM)
• 31: Open wound of abdomen, lower back, pelvis and external genitalia
• .6: Open wound of abdominal wall with penetration into peritoneal cavity
• 07: Left flank, unspecified wound type
• S (7th character): Sequela, meaning the encounter addresses a late effect of the original injury

The “unspecified” designation in the wound description means the record does not identify the wound as a laceration, puncture, or other specific type. If the clinical documentation does specify the wound type, a more precise sibling code should be selected instead of S31.607S.

Accurate patient record management at the point of care prevents this type of under-documentation.

The left flank locator is anatomically important. This region sits lateral to the descending colon and overlies the left kidney and proximal left ureter.

It also lies near the inferior pole of the spleen, with the lateral abdominal wall musculature and fascia forming the wound’s immediate layers. A penetrating wound into the peritoneal cavity at the left flank risks injury to these retroperitoneal structures. That is why ICD-10-CM tracks flank specificity at the 7th character build-out stage.

The S31.607 code family: 7th character variants (A, D, S)

S31.607 without a 7th character is not billable. The parent code exists only as a placeholder in the code hierarchy. To submit a valid claim, coders must append one of three 7th characters, each reflecting where the patient is in their care journey. The same initial-encounter convention applies to injury codes like S21.112A across trauma practices.

A common documentation error: coding S31.607S when the wound is still actively being treated. The sequela character is for late effects only, after the wound itself has resolved. Practices that use digital clinical forms that prompt for wound status at each encounter reduce this type of coding error significantly.

Understanding the sequela (S) 7th character in ICD-10

The sequela designation is one of the most misapplied 7th characters in ICD-10-CM injury coding. Sequela are defined in the CMS ICD-10-CM coding guidelines as the late effects of a previous injury. The injury itself no longer requires treatment, but it has left a residual condition that now drives the clinical encounter.

For S31.607S specifically, the sequela might be an abdominal wall scar causing chronic pain. It could also be a hernia at the former wound site or adhesive disease from peritoneal irritation. Patients managing chronic post-wound pain sometimes move into physical therapy, where physical therapy EMR software needs the same sequela documentation to justify continued care.

The original penetrating injury is coded as the cause, using an external cause code. The sequela code, S31.607S, captures the current presenting condition.

When to use S31.607S vs S31.607A vs S31.607D

The distinction between subsequent encounter (D) and sequela (S) trips up even experienced coders. The wound’s healing status is the deciding factor.

• Use S31.607A (initial encounter) when the patient is receiving active treatment for the penetrating abdominal wound. This includes emergency surgery, wound closure, or any encounter where the wound is the primary clinical problem being addressed.
• Use S31.607D (subsequent encounter) when the wound is still healing but active treatment has concluded. Follow-up visits for wound monitoring, dressing changes, or suture removal fall here. The wound exists and is still on the problem list.
• Use S31.607S (sequela) when the wound has healed completely and the patient returns for a condition directly caused by that prior injury. The wound is no longer the problem. The late effect is.

One practical test: if the encounter note describes wound status (open, draining, healing), use A or D. If the note describes a chronic condition traced back to the healed wound, use S. For guidance on applying this distinction across trauma ICD-10 families, the CDC/NCHS ICD-10-CM web tool provides the official tabular list with coding instructions.

S31.607S code hierarchy and parent codes

Knowing the code tree helps coders navigate the ICD-10-CM structure when S31.607S does not precisely fit a case and a related code needs consideration. The hierarchy from broadest to most specific is:

• S00-T88: Injury, poisoning and certain other consequences of external causes (Chapter 19)
• S30-S39: Injuries to the abdomen, lower back, lumbar spine, pelvis and external genitalia
• S31: Open wound of abdomen, lower back, pelvis and external genitalia
• S31.6: Open wound of abdominal wall with penetration into peritoneal cavity
• S31.60: Unspecified open wound of abdominal wall with penetration into peritoneal cavity
• S31.607: Unspecified open wound of abdominal wall, left flank, with penetration into peritoneal cavity (non-billable parent)
• S31.607S: ICD-10 Code S31.607S (billable, sequela encounter)

The S31.6x block specifically requires peritoneal penetration documentation. If the wound does not penetrate the peritoneal cavity, codes from S31.10x-S31.13x (open wound without peritoneal penetration) apply instead.

Reviewing ICD-10 code S15.029S illustrates how the same sequela logic applies across different body systems. For the official hierarchy, the WHO ICD-10 browser provides the international classification context from which ICD-10-CM descends.

Related ICD-10 codes for abdominal wall open wounds

Accurate differential coding requires knowing the sibling and adjacent codes that share the S31.6x parent. S31.607S covers the left flank, one of several quadrant- and flank-specific options in that family.

Other regions, bilateral wounds, and wounds with specified wound types each have their own codes. The table below lists the codes coders confuse with S31.607S most often.

When selecting between S31.607S and the unspecified quadrant code S31.609S, always default to the flank-specific code if documentation supports it. The left flank is almost always identifiable from operative notes or imaging reports. Choosing S31.609S when the flank is documented is a coding specificity error.

Clinical documentation requirements for ICD-10 Code S31.607S

A denied claim for S31.607S most often traces back to missing documentation of one or more required elements. Every element below must appear in the medical record to support this code. The medical forms and documentation workflows a practice uses directly affect how consistently these elements are captured.

Practices using plastic surgery EMR software or surgical practice management systems should configure their wound follow-up templates to include each of these fields.

• Wound location: Left flank of the abdominal wall must be documented explicitly
• Peritoneal penetration: Operative notes or imaging must confirm penetration into the peritoneal cavity from the prior injury
• Wound healing status: Documentation must confirm the original wound has healed, distinguishing this as a sequela rather than an active or subsequent encounter
• Nature of the sequela: The specific late effect driving the visit must be described (adhesion, scar, hernia, chronic pain at the wound site)
• Link to prior injury: The history must connect the current late effect to the previous penetrating wound. An external cause code from the original injury supports this connection.
• Wound type qualification: If the wound type is known (laceration, puncture), a more specific code replaces S31.607S. “Unspecified” applies only when the operative record does not identify the wound type.

Pabau’s guide to HIPAA compliance covers record retention requirements relevant to trauma-related encounters.

ICD-10-CM official coding guidelines for S31.607S

The ICD-10-CM coding guidelines published by CMS and NCHS govern how sequela codes in Chapter 19 are reported. Several rules directly affect S31.607S:

• Two-code rule for sequela: When coding a sequela, two codes are typically required. The first code identifies the nature of the sequela (for example, a scar or adhesion). The second code is the sequela code itself (S31.607S), which identifies the cause as the prior injury. The sequela code comes second in sequencing unless the late effect is the principal diagnosis.
• No time limit on sequela: There is no minimum or maximum time that must pass before using the S 7th character. A patient can present with a wound sequela six weeks or six years after the original injury. The clinical decision is whether the original wound has healed.
• External cause code: Report the external cause of the original injury with a 7th character of S when coding sequela encounters. This helps payers and public health registries track injury outcomes accurately.
• Active vs. healed distinction: Do not report S31.607S alongside S31.607A or S31.607D for the same injury episode. These characters are mutually exclusive for any single encounter.

The National Center for Health Statistics maintains the official ICD-10-CM guidelines, updated annually. Wound-closure procedures billed alongside a sequela diagnosis, such as CPT code 15155, follow a similar documentation standard for the operative record.

Approximate synonyms and clinical terms for S31.607S

The ICD-10-CM alphabetic index maps several clinical terms to S31.607S. Coders working from physician narrative notes should recognize these alternate terms as indicators for this code. The same synonym-mapping challenge shows up across other injury codes, including S22.068B, so charge capture workflows benefit from building a shared terminology list.

• Sequela of open wound, left flank of the abdomen, with peritoneal penetration
• Late effect of penetrating abdominal wound, left flank
• Scar/adhesion sequela, abdominal wall penetrating injury, left flank
• Open wound NOS, left flank abdominal wall, peritoneal cavity, sequela
• Chronic late effect, penetrating left flank abdominal injury

None of these synonyms imply a specific wound type such as laceration or puncture. If a physician’s note uses those terms, and the original operative record confirms the wound type, a more specific S31.6x code should replace S31.607S. That replacement code carries the appropriate wound-type digit.

How Pabau helps practices code wound sequelae accurately

Coders reviewing abdominal wound cases often rely on scattered chart notes to decide whether a claim needs an active-treatment character or the sequela character. When a follow-up note doesn’t state that a wound has healed, the coder has to chase down the clinician before submitting the claim. That delay pushes back reimbursement.

Practice management software like Pabau standardizes wound-status fields directly inside the encounter template. Clinicians then confirm whether a wound is active, healing, or resolved at the point of care.

Pabau’s claims management software then carries that structured status straight into the claim. The coder sees exactly the documentation needed to select S31.607A, S31.607D, or S31.607S without re-reading the chart.

The result is fewer denials tied to 7th-character mismatches and faster turnaround between the visit and a clean claim submission for surgical and trauma practices.

Reduce coding errors on abdominal trauma claims

Pabau's claims management software helps surgical and trauma practices document wound status accurately at every encounter, supporting correct 7th character selection and cleaner claim submissions.

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Conclusion

S31.607S denials usually trace back to one of two errors. A coder selects the sequela character while the wound is still healing, or the note never states the specific late effect driving the visit. Structured encounter templates prevent both mistakes.

Getting the 7th character right the first time avoids costly resubmissions and keeps trauma coding audit-ready. Book a demo to see how Pabau’s claims management software supports accurate wound-sequela documentation for surgical practices.

Continue your research

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