Common and Serious Coding Mistakes to Watch Out For

by | Published on May 19, 2020 | Medical Coding

Coding Mistakes
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Knowing the basics of CPT and ICD 10 coding, modifier use and payer guidelines is essential for physicians to get paid for the services they provide. Errors in CPT and ICD -10 coding can not only lead to loss of revenue but also cause compliance problems and attract the attention of government and private insurance auditors. Outsourcing medical billing and coding to an experienced service provider can help practices stay on track, but it’s important that physicians are aware of the common medical coding errors that can get labelled as “fraud” and “abuse” and prove financially damaging.

    • Choosing the wrong CPT code: According to an ICD-10 Monitor report, the main sources of wrong CPT codes are incomplete or inaccurate code descriptions on encounter forms, cheat sheets and electronic charge systems. With thousands of CPT codes to choose from, including new codes introduced every year, choosing the right code to describe a procedure or service can be a major challenge. Common problems in coding surgical procedures include: unbundled procedures, not coding multiple procedures when required, missing charges when multiple procedures are performed, coding from the operative note headers rather than after reviewing the details of the entire procedure in the documentation, and reporting units incorrectly.While it may seem easy to identify which services were provided to patients, it is important to select the code that best represents the services furnished. The codes selected should be based on the clinical documentation. For correct coding, it is also critical to know which codes can and can’t be reported together. Not using the correct combination of codes will lead to denials. There are guidelines in each CPT section, and there are notes and descriptive qualifiers in each subsection, subheading, category, and subcategory. Being familiar with these guidelines is necessary for compliant coding.
    • Not linking the diagnosis codes: While CPT codes describe the services rendered to the patient, ICD-10 codes determine the diagnosis and inform the payer of the reason why the services were provided. Correct ICD-10 coding depends on translating documentation into codes. When a definitive diagnosis is established, the coder should not assign codes for signs and symptoms of that illness. However, additional signs and symptoms as well as other conditions, should be coded when they are appropriate to the care provided during the visit.The ICD-10 codes should be linked to service/procedure codes. If a patient presents with more than one condition that are not related, unrelated services would be provided. Suppose a patient presenting for hypertension has a wart removed during the same visit. In this case, ICD-10 Monitor explains that the CPT code for the office visit must be linked to hypertension and the CPT code for the wart destruction must be linked to the diagnosis code for warts. If only one diagnosis is documented, it would lead to claim denial.
    • Improper use of modifiers: Modifiers are two-digit codes that can be used to inform the payer of special circumstances of the patient’s encounter with the physician. Modifiers can be used on both CPT and HCPCS codes to indicate various situations:
      • A service or procedure represents only a professional or a technical component
      • More than one physician performed a service or procedure
      • Services were reduced or only part of a service was performed
      • A distinct procedure service was performed
      • An adjunctive service was performed
      • A bilateral procedure was performed
      • A service or procedure was provided more than once
      • Unusual events occurred
      • A procedure or service was altered in some way
      • A procedure was discontinued

Correct modifier use is critical for revenue and compliance. Using modifiers requires an understanding of the global surgical package and the national correct coding initiative (NCCI) edits. As a miscoded CPT modifier can result in a denied claim, knowledgeable coders always look out for certain restrictions, formats, and guidelines that guide modifier use.

According to AHIMA, modifier –25, Significant, Separately Identifiable E/M Service and
-modifier 59, Distinct Procedural Service are the ones that are most commonly misused. Let’s look at an example of improper use of modifier -25 (

An established patient returns to the orthopedic physician with escalating right knee pain 6 months post a series of Hyaluronan injections. After evaluating the condition and determining the patient’s medical suitability for the procedure, the physician decides a second series of hyaluronan injections is needed and performs the first of three intraarticular injections. In this case, it would not be appropriate to bill the E/M visit with modifier 25, since the focus of the visit is related to the knee pain, which is the reason for the injection procedure. The evaluation of the knee problem and the patient’s medical suitability for the procedure is included in the injection procedure reimbursement.

Another concern is the confusion between modifier -25 and modifier -59 due to their similarity (ACP Internist). Modifier -25 should be used when it is necessary to indicate that on the day a procedure or service identified by a CPT code was performed, the patient’s condition required a significant, separately identifiable E/M service above and beyond the other service provided or beyond the usual preoperative care associated with the procedure that was performed. For e.g., if a minor surgical procedure is performed by the physician on the same day as an E/M service, modifier 25 should be used. The physician should provide separately identifiable documentation of the components of the E/M service and of the non-E/M service.

On the other hand, modifier -59 Distinct Procedural Service, identifies procedures or services that are not normally reported together. According to the CPT 2015 Professional Edition, it represents “a different session, different procedure or surgery, different site or organ system, system incision/excision, separate lesion or separate injury” that is not normally addressed on the same patient visit. Documentation should also support this.
Points to note:

      • Modifier -59 should not be used on an E/M service code.
      • The 59 modifier should be used on the non-E/M service code when billing for an E/M service and a procedure that is not typically included in an E/M visit, or is not typically done on the same day.
      • Modifier 59 should be used when no other existing modifier applies to distinguish appropriately billable services.
      • Medicare may have restrictions on the use of the modifier to bypass an edit.

The general role of modifiers is to provide more information to the payer and appropriate use is important to prevent loss of reimbursement. However, adding a modifier just to get it paid, if not supported, is fraud. Physicians should also remember that comprehensive documentation to support modifier use is critical to get paid.

  • Reporting unlisted codes without documentation: Unlisted codes or “Not otherwise specified” codes allow physicians report and track services and procedures that do not have a specific CPT code. By reporting an unlisted code with proper documentation, physicians can bill and receive reimbursement even for a procedure that does not have a specific CPT code. Documentation requirements for unlisted codes include:
    • A clear description of the nature, extent, and need for the procedure or service
    • Patient’s diagnosis and risk of complications
    • Whether the procedure was performed independent from other services provided, or performed at the same surgical site or through the same surgical opening
    • Time, effort, and equipment necessary to provide the service
    • The number of times the service was provided
    • What was found during the surgery (e.g., size and location of lesions)
    • Any other problems that the patient has and the follow-up care will be provided


Getting prior authorization from the payer before performing an unlisted procedure is important to get reimbursed for elective cases.

There are also specific rules with regards to reporting time-based infusion and hydration codes, injection codes, and multiple codes. Other common coding mistakes include upcoding and downcoding, and unbundling codes.

With their hectic schedules, the best option for practices to ensure error-free claims would be to partner with an experienced medical billing company. Such companies would have expert certified coders and the tools and processes required to help practices with proper claim submission. In addition to being well-versed on the essentials of medical coding, expert coders would keep up to date on new coding rules, which is crucial to ensure optimal physician reimbursement.

Natalie Tornese

Holding a CPC certification from the American Academy of Professional Coders (AAPC), Natalie is a seasoned professional actively managing medical billing, medical coding, verification, and authorization services at OSI.

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