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Spelling Out Medical Necessity; Duplicative Coding

Spelling Out Medical Necessity; Duplicative Coding


Q:  Does a diagnosis code alone support medical necessity for lab tests?  Shouldn’t there be something in the note documenting a sign/symptom or current status of the condition?  I do not think that by simple virtue of having a confirmed diagnosis that lab tests are always medically necessary.

A:  Medical necessity is largely determined by the payer community, usually assigned to them by your contract. There are a few ways to look at this.

From a purely payer policy perspective many lab codes have pre-determined lists of payable diagnoses codes, some with lists of necessary but non-payable codes and some with lists of always non-payable codes. This is by payer policy alone and not dependent on documentation.

If you are asking what documentation needs to be in the chart to support a given diagnosis, this is a slightly different question. The ICD-10-CM Official Guidelines for Coding and Reporting give the following two sets of guidance:

"For encounters for routine laboratory/radiology testing in the absence of any signs, symptoms, or associated diagnosis, assign Z01.89, Encounter for other specified special examinations. If routine testing is performed during the same encounter as a test to evaluate a sign, symptom, or diagnosis, it is appropriate to assign both the Z code and the code describing the reason for the non-routine test.

For outpatient encounters for diagnostic tests that have been interpreted by a physician, and the final report is available at the time of coding, code any confirmed or definitive diagnosis documented in the interpretation. Do not code related signs and symptoms as additional diagnoses."

In all of the cases described above, absence of signs/symptoms or tests to evaluate a sign or symptom, we would expect that the earlier part of the note, the history of presenting illness (HPI), would develop the reason for the encounter and any problems or contexts that would necessitate diagnostic testing.

The third "General Principle of Medical Record Documentation" from the Federal Documentation Guidelines is:

"If not documented, the rationale for ordering diagnostic and other ancillary services should be easily inferred."

So between the ICD-10 Guidelines and the Federal Documentation Guidelines, it is pretty clear the reason for every test needs to be spelled out. Whether a payer recognizes necessity is a different story.


Q: I have a provider whose every note begins, "Patient … is seen for initial visit. See review of systems (ROS) for wording." The intent from the provider is that the ROS contains the history of presenting illness.

A: Show the provider the definition of an HPI from the Federal Guidelines:

"The HPI is a chronological description of the development of the patient's present illness from the first sign and/or symptom or from the previous encounter to the present. It includes the following elements:

• Location,

• Quality,

• Severity,

• Duration,

• Timing,

• Context,

• Modifying factors, and

• Associated signs and symptoms."

Unless the ROS contains these types of descriptors and they usually don’t, for new patients I doubt the HPI will ever get past a 99202.


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