Internal Medicine Coding Alert

How to Choose the Correct ICD-9 Codes For Diagnostic Tests and Lab Work

- Published on Wed, Dec 01, 1999
The previous issue of Internal Medicine Coding Alert covered how to correctly apply diagnosis codes for screening diagnostic tests and lab work (tests ordered as a preventive measure when the patient is not expected to be ill). Applying the correct ICD-9 codes for laboratory work is complicated, however, even when the test is prompted by a symptomatic patient and is not a screening.

Should you choose the ICD-9 code that indicates the signs or symptoms that prompted the test? Or should you wait for the test results and use the code that specifically states the patients condition?

And regardless of whether signs and symptoms or the final diagnosis is recorded, should the requesting physician or the laboratory coders assign the ICD-9 code?

It is difficult for coders to know what to do because there is conflicting information in writing, advises Barbara J. Cobuzzi, CPC, MBA, CHBME, president of Cash Flow Solutions Inc., a physician practice billing company in Lakewood, NJ. I know how I think it should be done, but I cannot find it definitively in writing anywhere.

Diagnosis Coding When Test Is Negative

Actually, assigning a diagnosis code when the test is ordered and comes back negative is not as controversial as when the test comes back positive for the suspected problem.

If it is a screening (and screening means there are no signs or symptoms or a chief complaint) and the test comes back negative, use a V code for a screening such as V76.44 (screening for prostate cancer). If the patient has signs and symptoms and the test is negative, I recommend coding the signs and symptoms, Cobuzzi says.

For example, a patient comes to the internist complaining of frequent severe thirst and episodes of weakness. The physician orders a complete metabolic panel to detect or rule out diabetes or kidney dysfunction. In the section for diagnostic information on the form sent to the lab, the physician lists the ICD-9 codes 783.5 (excessive thirst) and 780.79 (generalized weakness).

The Medicare Carriers Manual (MCM) section 4020.3, Item 23A, Diagnosis or Nature of Illness or Injury, states that Physicians must use the appropriate code or codes from 001.0 through V82.9 to identify diagnoses, symptoms, conditions, problems, complaints, or other reason(s) for the encounter/visit.

The phrase reason for the encounter/visit seems to indicate that the physician should assign a diagnosis code that indicates the signs or symptoms that prompted the test or lab work.

The MCM continues: List first the ICD-9-CM code for the diagnosis, condition, problem or other reason [...]

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