Groin and Flank Injury Documentation

Why this update matters

A generic entry such as “abdominal injury” may not provide enough detail to select a specific groin or flank code. Capture the distinguishing findings at the encounter so the coding team can use the expanded options accurately and report the injury actually evaluated and treated.

Document the details that distinguish the injury

• Exact site: Identify the groin, right or left flank, or another part of the abdominal wall. Record laterality even when a particular code does not encode it.
• Injury type: Distinguish contusion, abrasion, nonthermal blister, constriction, superficial foreign body, insect bite, superficial bite, or open wound.
• Open-wound details: Specify laceration, puncture, or open bite; whether a foreign body is present; and whether the wound penetrates the peritoneal cavity.
• Treatment phase: Describe the active treatment, routine healing care, or residual condition being addressed. The coder applies the appropriate encounter character. [1][3]

Three examples for the clinical note

Left flank contusion: Document the side, findings, mechanism when known, assessment, and care. S30.13XA describes an actively treated flank contusion, but the code itself does not distinguish left from right.

Right flank laceration with foreign body, without peritoneal penetration: When supported by the record and active treatment, the example code is S31.126A.

Left flank open bite with peritoneal penetration: When supported by the record and active treatment, the example code is S31.657A. [1]

Do not infer wound penetration or a retained foreign body. Clarify missing clinical information with the treating provider. Code examples illustrate documented scenarios; they do not determine coverage or payment.

Contusion and superficial injury reference

Complete initial-encounter codes are shown below. These selected families do not distinguish right from left, even though laterality belongs in the clinical record. [1]

Choose the seventh character by treatment phase

• A — Initial encounter: Active treatment, such as evaluation and treatment in the ED or surgical management. It is not limited to the first visit.
• D — Subsequent encounter: Routine care during healing or recovery after active treatment is complete.
• S — Sequela: A residual effect of the injury. Generally report the residual condition first, followed by the injury code with S. [3]

An ED return for worsening pain does not automatically mean A. Determine whether the patient is receiving active treatment, routine healing care, or care for a residual effect. A change in clinician or location alone does not decide the character. [3]

The seventh character must occupy the seventh position. Keep required X placeholders. In S30.81AA, the first A is part of the code; the final A identifies the encounter. Change only the final character to D or S when appropriate.

Flank open-wound reference

These codes describe open wounds of the abdominal wall in the flank region. All entries below are complete initial-encounter codes. Penetration refers specifically to the peritoneal cavity. [1]

Use the reference with the full code set

For subsequent care or sequela, replace only the final A with D or S when the reporting rules are met. For example, S31.126D describes subsequent care for the same right-flank wound; S31.126S identifies its sequela. [1][3]

This selected list is not exhaustive. The coding team should confirm the Alphabetic Index, Tabular List, inclusion and exclusion notes, and additional-code or sequencing instructions. Record associated injuries and complications when present. [3]

Code-set verification: The FY2026 expansion took effect October 1, 2025. Examples in this guide were checked against FY2027 official files. Select the code set and applicable updates effective for the date of service. [2]