Diagnosis Coding Done Right

Report what documentation tells you, or you could be hurting the patient.

By Debra Mitchell, MSPH, CPC-H

Imagine this patient encounter: A 67-year-old female complains of a painful lump on her elbow. The physician performs an assessment and takes a biopsy. Both the office visit and the biopsy are linked to ICD-9-CM code 757.8 Other specified congenital anomalies of the integument, and the claim is paid. Pathology results later reveal a diagnosis of giant cell tumor.

The physician refers the patient to a specialist to have the tumor removed. Prior to receiving a pathology report, the removal claim is submitted with ICD-9-CM code 215.2 Other benign neoplasm of connective and other soft tissue; upper limb, including shoulder. When the pathology results arrive, they indicate a diagnosis of osteosarcoma.

The specialist now recommends amputation of the arm, but the payer will not authorize the procedure as medically necessary, based on previous diagnoses submitted. From the payer’s point of view, the information does not add up. Why would amputation be necessary for a benign congenital anomaly? Although the previous claims were paid, the coding was incorrect. Sorting out the confusion will cause delays for the patient and provider.

Such a scenario is distressingly common. Claims often are submitted for payment with incorrect or unconfirmed diagnoses not based on documentation.

More Distressing Coding Examples

To cite another example, an office may choose not to report V codes based on a rationale that payers have stated V codes are not acceptable as a primary diagnosis. When a patient undergoes pre-employment hepatitis screening, for instance, the claim is submitted with 573.3 Hepatitis, unspecified. The claim gets paid, but the patient has been falsely labeled with a condition that will inappropriately increase his risk factor and premiums, and may negatively affect his benefits.

Or, perhaps the provider understands that V codes can gain payment, but applies them improperly. For example, when submitting lab work for HIV screening, a diagnosis of V08 Asymptomatic human immunodeficiency virus [HIV] infection status is submitted. The claim gets paid, but the harm to the patient’s file is enormous.

Here’s another scenario: A patient is taking a medication as prescribed by her physician. She experiences a severe reaction to the medication and is hospitalized. Her codes upon discharge are 965.00 Poisoning by analgesics, antipyretics, and antirheumatics; opium (alkaloids), unspecified, 570 Acute and subacute necrosis of liver, 304.0 Opioid type dependence, and E850.2 Accidental poisoning by analgesics, antipyretics, and antirheumatics; other opiates and related narcotics.

The only problem with this coding summary is none of it is true and none of it is documented—with the exception of the liver necrosis. The patient is hospitalized in a different facility, which receives the old chart with the coding summary. As explained to the family, pain drugs are withheld due to the patient’s IV drug abuse. In reality, the patient was never an IV drug abuser.


Coding for payment (rather than for accuracy) has serious repercussions—not just because of payer audits or repayment demands, but for patients, as well.

Lessons to Learn

Coding for payment (rather than for accuracy) has serious repercussions—not just because of payer audits or repayment demands, but for patients as well. Patients’ insurance collects data from our claims regarding their subscriber. This data is used to establish patients’ risk profiles, which will help the payer establish the premium amounts and access to benefits. Choosing diagnosis codes based on whether they will be paid can artificially and incorrectly cause a patient’s risk to be higher than it is suppose to be. How can you help prevent this?

For starters, when selecting an ICD-9-CM code, there is no substitute for using an official ICD-9-CM code book (be it electronic or paper). Codes cannot be selected from memory or from a cheat sheet. Code books have important instructions and structure that can assist with code selection. A code never should be taken out of context.

For example: 964.2 Anticoagulants might seem to be appropriate for a patient on anticoagulants, but it is in the category 964 Poisoning by agents primarily affecting blood constituents, in the chapter for Injury And Poisoning. It should not be used to indicate a patient is on an anticoagulant, as you might expect, but rather to indicate poisoning by anticoagulates. Another code frequently used for prothrombin time and international normalized ratio (PT/INR) tests for patients on anticoagulation therapy is 286.9 Other and unspecified coagulation defects. This code should not be used just because the patient is on an anticoagulant if the provider did not document the specific condition of coagulation defect.

Above all, remember that the diagnosis belongs to the patient. Payers can make policy based on what they consider appropriate medical necessity for a procedure or service, or what diagnosis they consider to be covered, but a payer cannot tell the provider which diagnosis code to select for the claim. As well, the code we select must match the provider’s documentation, following coding guidelines and ICD-9-CM conventions. Do not assign codes without complete documentation (e.g., relevant pathology results). When in doubt, query the provider for more information. As a professional medical coder, it is your responsibility to strive to be 100 percent correct with diagnosis code selection.


Debra Mitchell, MSPH, CPC-H, is a consultant and auditor for coding and compliance and a professional coding instructor. Her educational experiences coincide with her 34 years of medical records and billing experience at every level of responsibility. She was recently named to “Who’s Who in America’s Professional Women.”


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