Friday, February 18, 2011

Common ICD-9-CM Coding Errors

Usually, it’s a misunderstanding the rules of ICD-9 –but no matter the reason, many codes are found to be unsupported in a Risk Adjustment Data Validation or other audit.  The most common reasons for this seem to be that the ICD-9 doesn’t “talk” the way doctors do, or the person choosing the code doesn’t know that there’s a special rule related to it.  In an audit situation, the cause isn’t relevant—an error is an error.  The best way to avoid these errors is to make physicians aware of these common problems, and help them understand the ICD-9 rules.  Remember that those rules include Coding Clinic, which is officially tasked with clarifying coding rules for ICD-9.  So, what are the most common errors we see?

“Wound care” coding – Every time I drive by a wound care clinic, or see wound care written in a chart, I cringe.   I know that there’s a coding error ahead.  When you search the alphabetic index of the ICD-9 for the term wound, you won’t find any decubitus or vascular ulcers. You’ll see operative wounds (incisions) or lacerations (cuts).  I *know* what the provider means – he/she is treating an ulcer.  But if the doctor doesn’t call it an ulcer, choosing an ulcer code is wrong.  Physicians need to be instructed in the proper documentation for ulcers—location and type of ulcer must be described for vascular ulcers. For decubitus ulcers, the location, type (decubitus/pressure) and stage of ulcer must be documented.  For decubitus ulcers, two codes must be selected—one for the location and one for the stage.

Coronary Artery Disease (CAD) coding—Almost always, when I see a diagnostic statement of “CAD”, the code 414.00 (coronary artery disease, of unspecified type of vessel, native or graft) is attached.  Isn’t that correct? It sounds correct. No one mentioned whether it was a native or graft vessel, so it has to be correct! Except that it’s not. If there is no record of prior coronary artery bypass grafting, the correct code is 414.01 (coronary artery disease, of native coronary artery), because there’s a Coding Clinic that says so.  In Q2 1995, the following Coding Clinic ruling was issued:
Is it appropriate to assign code 414.01, Coronary atherosclerosis, of native coronary artery, if the medical record documentation does not indicate that the patient has a history of prior coronary artery bypass surgery?

"Assign code 414.01, Coronary atherosclerosis, of native coronary artery, if medical record documentation shows no history of prior coronary artery bypass. If the documentation is unclear concerning prior bypass surgery, query the physician."

Aortic Atherosclerosis coding – Documentation that indicates “aortic atherosclerosis” or “atherosclerosis of the aorta” without further clarification cannot be coded according to Coding Clinic, Q4, 1988.  If the physician can be queried (i.e., the note is new, and can be amended within approximately 72 hours of the visit) then the physician can clarify whether it is the aorta (vessel) or the aortic valve.  If it is the vessel, then the correct coding is 440.0.  Atherosclerosis of the aortic valve is coded 424.1.  Going forward, the physician should be sure to clarify whether it is valve or vessel.  For example, noting that there is atherosclerosis of the abdominal aorta makes it clear that it is the vessel.

Hemiparesis vs. Weakness -  We often see documentation that states “history of CVA with R. sided weakness”, and the physician has selected 438.20 –late effect of CVA, hemiparesis/hemiplegia of unspecified side.  While paresis does mean weakness, the issue is a little more complicated.  The term hemiparesis means more than weakness, it means weakness affecting an entire side of the body. And, in this case, it’s not just about the definition—but coding rules.   In Q1 2005, Coding Clinic was asked the following question:

Please provide clarification on the correct code assignment for a residual deficit of muscle weakness secondary to late effect of cerebrovascular accident. We have a difference of opinion on whether this should be coded to code 438.2x, Late effects of cerebrovascular disease, hemiplegia/ hemiparesis. What is the appropriate code assignment for residual weakness that is a late of effect of CVA?
Assign code 438.89, Other late effects of cerebrovascular disease and code 728.87, Muscle weakness, for residual muscle weakness secondary to late effect of cerebrovascular accident.
Therefore, when the physician documents weakness secondary to an old CVA, you cannot code 438.20.  Physicians must be educated regarding this rule, so that they can adjust their documentation going forward.

Finally, there’s a whole group of diagnoses that are coded when the physician really means that the patient had them in the recent past.  We see this most often when a patient is seen for the first time in the office after a hospitalization for:

      Acute MI (except in 1st 8 weeks)
Acute Coronary Syndrome
Non-ST Elevation MI (NSTEMI)
Unstable Angina
Acute Respiratory Failure

Once the patient has been discharged from the hospital, these conditions should no longer be coded. In some cases, it’s appropriate to code the “history of” code, or the underlying condition.  But coding these conditions in the office setting is only appropriate if the patient presents in the office and is (generally) transported by ambulance to the hospital.

There are other common errors that we see, but these are among the most common.  Understanding coding rules can help you avoid these pitfalls.

Do you have questions about coding rules?  Leave us a comment or email your question to

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