Coding to the Highest Level of Specificity to Reduce Denials

Insurance carriers often deny claims for not being coded to the highest level of specificity or they may consider the diagnosis truncated.  As many billers are not coders, they often don’t understand what has gone wrong or how to fix it.

What is the highest level of specificity?

If a service line is denied for this reason, the payer is saying that the diagnosis code needs to be more specific.  Some diagnosis codes are only three or four digits, but many are five.

The diagnosis must be coded to the absolute highest level for that code, meaning the maximum number of digits for the code being used.  You may have a four-digit diagnosis code that needs to be five digits to be accepted.

Examples of Coding Specificity
The diagnosis for hypertension begins with 401; however, if you submit a claim with the diagnosis 401, it will be denied.  The code 401 requires a fourth digit, like 401.0, which is malignant essential hypertension.

Benign essential hypertension is 401.1. Unspecified essential hypertension is 401.9.  So, to bill a claim with a diagnosis of hypertension, it must be 401.0, 401.1, or 401.9.

Another example of a diagnosis needing to be billed to a higher level of specificity would be diabetes.  To indicate diabetes, use the code 250.0; however, you need a fifth digit to specify what type of diabetes.

Diabetes mellitus type two is 250.00, diabetes mellitus type one (juvenile type) is 250.01, diabetes mellitus type one uncontrolled is 250.02 and so on.

As you can see in the above example just putting 250.0 does not indicate specifically enough what the problem is.  Without the fifth digit, the claim is lacking enough information to be processed and therefore will be denied.

How to Spot Under Coding
If you are unsure if the diagnosis is coded to the highest level of specificity, you can look it up in an ICD-9 codebook or on the web.  There are several websites with current ICD-9 codes available.  They will indicate if the code is coded to the highest level.

Some practice management systems have scrubbers that will catch under-coded diagnoses and give you a warning.  Sometimes, the biller may recognize a truncated diagnosis (or a diagnosis requiring an additional digit).

In either case, the biller should go back to the coder or provider and ask them to be more specific with the diagnosis code, so the claim can be resubmitted.

Alice Scott and Michele Redmond are medical billing experts, co-owners of Solutions Medical Billing Inc in Rome, N Y., and coauthors of 14 books on medical billing and medical credentialing. This mother-and-daughter team maintains two medical billing websites, a free newsletter and an active forum. Alice and Michele are on the editorial staff of BC Advantage and are regular contributors to the magazine. Their books are available at


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