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May 2008

Savvy Coder: Coding & Reimbursement
How to Solve ICD-9 Conundrums: Some Rules of Thumb, Part One
By Gordon E. Johns, MD, and Sue Vicchrilli, COT, OCT, Academy Coding Executive

The diagnostic (ICD-9-CM) codes are used to establish why a service was medically necessary. Most of the time, it is easy to assign a diagnostic code—the problem is routine, the diagnosis straightforward. And reporting the diagnostic code to the insurance carrier is, in the vast majority of cases, also rather simple—the rules are clear, the process easy.

Occasionally, however, the condition simply may not be found in the ICD-9-CM book, or the circumstances might be convoluted. In these odd cases, you’ll need to be creative. And if you understand some basic rules of thumb, you’ll be able both to find and to report a code that clearly represents to the carrier why you needed to provide a service to the patient. Here are some of those “rules.”


Rule 1. Code to the highest degree of accuracy and completeness. If there is a fourth or fifth digit available, always use it. Failure to use a five-digit code when it is available will result in the claim being denied.

The best code is an actual diagnosis. Lacking a diagnosis, the next best code would be a sign or a symptom. But if there is not a sign or symptom to report, the last resort would be a circumstance (V Code).

Some codes are listed as “Other specified” or “Unspecified.” Although these are always acceptable, it is better to be more specific whenever possible.


Rule 2. ICD-9-CM instructions may differ from what the carrier expects. Throughout ICD-9-CM, you are often instructed to code first for the underlying disease. Under code 362.0, for example, you’ll see “362.0 Diabetic Retinopathy. Code first diabetes (250.5).” If you follow this instruction, you would assign a code for the underlying systemic diabetes before assigning one of the diabetic retinopathy codes. However, no insurance carrier demands that you follow this rule. They are all happy if you use the actual code for the diabetic retinopathy. Plus, of course, this much more clearly reflects the purpose of the patient’s visit to an ophthalmologist.


Rule 3. Do not code “probable,” “suspected” or “rule out” conditions until they are established. This principle clearly applies in the case of lid lesions for which you do not have a tissue diagnosis. Fortunately, there are some good alternatives: Lid neoplasms can be coded as benign, malignant, carcinoma in situ, uncertain behavior or unspecified nature. Until the nature of the neoplasm is actually known, it is best to use the classification of uncertain behavior.

Another example would be the patient who comes in with unilateral eye pain. Suppose you have ruled out angle-closure glaucoma and a host of other problems. You now are very suspicious that there is underlying sinus disease and you refer the patient to ENT. Rather than using a code that reflects the suspected sinus disease, you would use code 379.91, which has a descriptor —“Pain in or around eye”—that reflects the symptom.

Next month: More rules of thumb for your diagnostic dilemmas.

Dr. Johns edits the AAOE’s ICD-9 for Ophthalmology (product #012264). The 2008 edition costs $60 for members and $80 for nonmembers. Find out more at