Claim edit: An external cause code can't be the principal ICD-10-CM diagnosis code

Stedi now rejects 837P professional and 837I institutional claims that list an external cause code as the principal ICD-10-CM diagnosis code.

ICD-10-CM diagnosis codes

In healthcare claims, diagnosis codes describe what’s wrong with the patient. HIPAA requires that professional and institutional claims only use valid, billable ICD-10-CM codes as diagnosis codes. For example, M54.50 is the billable ICD-10-CM code for “Low back pain, unspecified.”

A claim can include multiple diagnosis codes. The first one listed – called the principal (or primary) diagnosis – is the condition primarily responsible for the visit. The rest are additional diagnoses.

Principal diagnosis code

External cause codes

An external cause code is an ICD-10-CM diagnosis code used to describe how an injury or condition occurred. For example, V03.10XA (pedestrian struck by car) is an external cause code. External cause codes always start with V, W, X, or Y.

How the edit works

External cause codes are valid ICD-10-CM diagnosis codes, but ICD-10-CM guidelines only allow them as additional diagnoses to supplement the principal diagnosis. External cause codes are not allowed as the principal diagnosis. Payers may reject claims that break this rule.

This edit catches the issue before the claim reaches the payer. It prevents payer rejections, which take longer to resolve and delay payment for the provider.

Rejection errors

If you submit a claim using Stedi's Claim Submission API endpoints and the claim fails the edit, you'll get back an error response in real time. The response includes details in the errors array:

{
  "errors": [
    {
      "code": "33",
      "description": "Invalid Principal Diagnosis. External cause codes, which describe how the condition occurred, cannot be used as the principal diagnosis. The submitted diagnosis code, W1830XA, is an external cause code (codes beginning with V, W, X, or Y). Correct and resubmit.",
      "followupAction": "Please Correct and Resubmit"
    }
  ]
}

If you submit a claim using SFTP and the claim fails the edit, Stedi will reject the claim with a 277CA claim acknowledgment. The acknowledgment will include a related claim status category code, claim status code, and error message:

STC*A7>254*[DATE]*U*[AMOUNT]******A7>509**Invalid Principal Diagnosis. External cause codes, which describe how the condition occurred, cannot be used as the principal diagnosis. The submitted diagnosis code, W1830XA, is an external cause code (codes beginning with V, W, X, or Y). Correct and resubmit.~

Resolution tip

In most cases, you can pass this edit by setting the principal diagnosis to the resulting injury or condition and listing the external cause code as an additional diagnosis.

For example, on a claim for a pedestrian struck by a car, list the injury, like S72.001A (fracture of the right femur), as the principal diagnosis and an external cause code, such as V03.10XA (pedestrian struck by car), as an additional diagnosis.

Related claim edits

Stedi has other edits that enforce principal diagnosis rules. See:

• A sequela code can't be the primary ICD-10-CM diagnosis code

• Invalid primary diagnosis on Medicare chiropractic claims