Q. Why was the ICD-9-CM code that I have been using for the last three years returned as truncated?
A. ICD-9-CM is composed of codes made up of three, four, or five digits. Codes with three digits are either stand-alone codes or headings of a category of codes that are further subdivided by the use of fourth or fifth digits, which provide greater specificity.
A truncated diagnosis code is an ICD-9-CM code not reported to the highest level of specificity, e.g., a claim submitted with a three-digit diagnosis code where a four- or five- digit code exists. Diagnosis codes must be submitted to the highest level of specificity.
Each year, the list of ICD-9-CM codes is modified to make sure that diseases are reported at the highest level of detail necessary to describe the patient's condition. Referring to most current ICD-9-CM book will help ensure proper diagnosis coding. Truncated diagnosis codes cause a claim to be rejected as unprocessable.
- Assign three-digit codes only if there are no four-digit codes within that code category (there are only about 100 codes in this category),
- Assign four-digit codes only if there is no fifth-digit subclassification for that category, and
- Assign the fifth-digit subclassification code for those categories where they exist.
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