Importance of Listing Primary Diagnosis Code First

The main purpose of a diagnosis is to determine, within a certain degree of accuracy, the underlying CAUSE of the patient’s condition. It is very critical to stress the importance of proper medical coding of a diagnosis. Accuracy, to the highest possible degree, is essential to reimbursement for services rendered; and to protection from both malpractice and civil litigation. One often hears the term, principal diagnosis, primary diagnosis, and first-listed diagnosis. Coders are often confused, as with some healthcare providers, what term should be used, not only when, but also under what circumstances of the patient. It is very important to understand the various terminologies that are often used interchangeably dependent on the patient’s situation before applying various terms

The definition of principal diagnosis (originally developed in 1985) under the Uniform Hospital Discharge Data Set (UHDDS) is said to apply only to inpatients during acute, short-term, long-term care and psychiatric hospitals, dependent on the length of stay parameters.

Below are the definitions of the different terms for principal diagnosis:


  • First-listed diagnosis:

    Terms “principal” and “primary” are often used interchangeably to define the diagnosis that is sequenced first. The term first-listed diagnosis/condition is used in the outpatient setting in lieu of principal diagnosis, and because of the timing. Moreover, in cases of an existence of a discrepancy, it is the first-listed diagnosis as per the coding conventions of ICD-10-CM, along with the general and disease-specific guidelines within ICD-10-CM, which will have precedence over the outpatient guidelines. Outpatient surgery encounter rules are to assign the diagnosis code as first-listed for the condition that the surgery was performed.
  • Principal diagnosis:

    Condition established after study to be chiefly responsible for the patient’s admission to the hospital. It is always the first-listed diagnosis on the health record and the UB-04 claim form. This direction applies to nursing homes as stated in the guidelines.
  • Primary diagnosis:

    This term is often used to indicate the reason for the continued stay in the LTC facility. It is also used interchangeably with the principal diagnosis.

The primary diagnosis should be listed first.

Other additional codes for any coexisting conditions are to be then listed. It should be remembered that, your diagnosis—the disorder you are evaluating and/or treating—is considered the primary diagnosis and should be listed first on the claim form. Other supporting diagnoses are considered secondary and should be listed after your primary diagnosis. In today’s medical parlance, Primary diagnosis is now termed as first-listed diagnosis.

Dos and Don’ts when coding using the first-listed diagnosis

  • Therapeutic services received only during an encounter/visit, the diagnosis should first be sequenced, followed by the condition. Problem or other reason should be assigned as secondary codes. However, when the primary reason is chemotherapy or radiation therapy, or rehabilitation, the exception here is, the appropriate V code for the service should be listed first, and the diagnosis or problem for which the service is being performed listed second.
  • It has been stressed by the guidelines laid down that the outpatient surgery encounter rules are to assign the diagnosis code as first-listed for the condition that the surgery was performed. But, in case there is a difference between the postoperative diagnosis & the preoperative diagnosis when the diagnosis is confirmed, the postoperative diagnosis or condition would be the most definitive diagnosis. Thus, the first-listed diagnosis or condition is governed by circumstances of admission, reflecting the reason the patient is present for the care.
  • It is noteworthy to understand here that, especially in the outpatient setting, codes for other diagnoses (e.g., patients treated for chronic conditions including medication management) and care should be sequenced as additional diagnoses and not as the first-listed diagnosis.
  • Take note that, chronic conditions may not always be the reason the condition is treated during the visit. But, the main reason for the visit, or what was addressed during the visit, should be the first diagnosis listed. For instance, in the case of a patient with a history of asthma, if the physician codes the exacerbation of the chronic condition – severe wheezing, coughing, chest tightness of breath, as the first-listed diagnosis, the reason for the encounter and codes as secondary diagnosis chronic asthma, the claim is likely to be reimbursed.
  • The place of service should never dictate the diagnostic code, only the documentation.
  • Do remember that E-codes assigned most regularly in the emergency department, should never be assigned as a first-listed diagnosis.
  • When using V codes, usually implemented for occasions when circumstances other than a disease or injury are recorded as a diagnosis or problem, they may be used as either a first-listed or as an additional diagnosis, but depends on the circumstances of the encounter/visit. For instance, routine outpatient prenatal visits which exhibit no complications V22.0, or V22.1, as the first-listed diagnosis can be used
  • If two or more diagnoses equally meet the definition for principal diagnosis, either diagnosis can be sequenced as the first-listed diagnosis
  • According to Medicare Rules, the principal (first-listed diagnosis) is the clinical diagnosis, in absence of a definitive pathologic diagnosis, at the time a claim is filed
  • Many of the codes may be interpreted as applying to more than one area with a slightly different description relating that code to that anatomical area. There are very specific rules that must be followed in the assigning of the codes. Medicare has historically set the precedent and standard which all other carriers follow. Group insurance, HMO's, PPO's, auto insurers and worker's compensation, all follow the precedents set by Medicare.

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Published By - Medical Billers and Coders
Published Date - Feb-17-2016 Back

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