For professionals in medical coding and billing, accurately differentiating between various diagnosis types—such as admitting, principal, primary, and secondary—is not just a matter of semantics but a critical component of precise claim submissions and healthcare data management. Understanding these distinctions is essential to ensure proper reimbursement, minimize claim denials, and maintain compliance with coding guidelines. Let’s clarify these terms to bolster your understanding and enhance your coding accuracy.
Understanding the “Admit Diagnosis”
The Admit Diagnosis is fundamentally the initial reason that prompts a patient to seek medical attention. This could be a symptom, sign, condition, injury, or disease that leads a patient to seek healthcare services, often in settings like the emergency department (ED). It represents the patient’s presenting problem at the point of initial encounter, regardless of whether they are formally admitted to the hospital as an inpatient. Think of it as the starting point of the medical narrative for a particular episode of care.
For instance, if a patient comes to the emergency room complaining of severe abdominal pain, “abdominal pain” would be considered the admit diagnosis. Even if further investigation reveals appendicitis requiring surgery and hospitalization, the initial reason for seeking care remains the abdominal pain.
Delving into the Principal Diagnosis
The principal diagnosis carries a more specific definition, particularly within the context of inpatient care. According to the Uniform Hospital Discharge Data Set (UHDDS) and the ICD-10-CM Official Guidelines for Coding and Reporting, the principal diagnosis is defined as “that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care.”
This definition highlights a crucial aspect: the principal diagnosis is determined after a thorough evaluation and study during the hospital stay. It’s not necessarily the admitting diagnosis. Consider the example of a patient who presents to the ED with chest pain (the admit diagnosis). After undergoing a series of examinations, including EKGs and blood tests, it is determined that the patient has suffered a myocardial infarction (MI). In this scenario, the acute myocardial infarction becomes the principal diagnosis because it is the condition that, after study, is found to be chiefly responsible for the hospital admission.
Primary Diagnosis: Severity and Resource Intensity
In contrast to the principal diagnosis, the primary diagnosis in an inpatient setting is often characterized by its severity and the intensity of resources it demands during the patient’s hospital stay. While sometimes the primary diagnosis can be the same as the principal diagnosis, it can also differ, especially in complex cases involving multiple health issues. The primary diagnosis can be understood as the condition that requires the most significant allocation of hospital resources or is the most clinically concerning during the patient’s admission.
Let’s take the example of a patient admitted through the ED for a severe nosebleed (epistaxis). The admit diagnosis is epistaxis. Upon evaluation, it’s discovered that the patient is on an anticoagulant medication without proper monitoring, leading to the nosebleed. During their stay, the patient also develops a more critical condition – a bleeding gastric ulcer, evidenced by bloody diarrhea and confirmed through further testing. While the patient was initially admitted due to epistaxis, the bleeding gastric ulcer becomes the primary diagnosis because it poses a greater immediate threat, requires more intensive treatment (like potential blood transfusions, endoscopy, and medication adjustments), and consumes more hospital resources compared to managing the nosebleed.
Secondary Diagnoses: The Supporting Cast
Secondary diagnoses, often referred to as comorbidities or complications, are additional conditions that coexist with the principal or primary diagnosis at the time of admission, or develop subsequently during the hospital stay. These diagnoses are like “side dishes” to the “main course” (principal or primary diagnosis). They contribute to a more complete clinical picture of the patient’s health status.
Using our previous example of the patient with epistaxis and a bleeding gastric ulcer, secondary diagnoses might include conditions like hypertension or type 2 diabetes, if the patient has these pre-existing conditions. These secondary diagnoses are not the primary reason for admission but are relevant to the patient’s overall care.
For a secondary diagnosis to be reported, it must meet the MEAT criteria – meaning it has been Monitored, Evaluated, Assessed, or Treated during the encounter or hospital stay. This documentation in the medical record justifies the inclusion of a secondary diagnosis in coding and billing.
Here are examples of how a secondary diagnosis might meet the MEAT criteria:
- Medical Evaluation: A patient admitted for pneumonia (principal diagnosis) is also known to have chronic kidney disease. If the physician monitors the patient’s kidney function during the pneumonia treatment, this meets the “Monitored” aspect of MEAT.
- Diagnostic Testing: A patient hospitalized for heart failure (principal diagnosis) undergoes blood tests to manage their diabetes (secondary diagnosis). Testing the A1c levels or adjusting insulin dosages constitutes “Evaluated” or “Assessed.”
- Therapeutic Intervention: A patient admitted for a surgical procedure (principal diagnosis) has a pre-existing pressure ulcer (secondary diagnosis) that requires daily wound care and dressing changes during their hospital stay. This active management is considered “Treated.”
- Escalated Care/Length of Stay: A patient admitted for a urinary tract infection (principal diagnosis) develops atrial fibrillation (secondary diagnosis) during their admission, requiring cardiac monitoring and potentially prolonging their hospital stay. This situation aligns with “Escalated hospital care/extended length of stay.”
- Increased Monitoring: Post-operatively, a patient recovering from hip replacement (principal diagnosis) exhibits sleep apnea symptoms (secondary diagnosis) necessitating continuous SpO2 monitoring and respiratory therapy consultation. This increased nursing and specialist attention falls under “Increased monitoring or nursing care.”
Image illustrating the concept of principal diagnosis determination after study
Navigating Multiple Admitting Diagnoses
In scenarios where a patient presents with multiple conditions that could independently warrant hospital admission, determining the principal diagnosis requires careful review. The ICD-10-CM coding guidelines offer specific directions for these complex situations. If uncertainty persists after a comprehensive review of the medical record, it is best practice to query the physician for clarification on which condition was the primary reason for the patient’s admission.
Conclusion
Accurate diagnosis coding is foundational to effective healthcare administration and revenue cycle management. Understanding the nuances between admit, principal, primary, and secondary diagnoses is crucial for coding professionals. By applying these definitions and adhering to official guidelines, healthcare organizations can ensure accurate claim processing, reduce denials, and maintain the integrity of patient data. Mastering these distinctions not only improves coding accuracy but also contributes to better healthcare data quality and informed decision-making in patient care and hospital management.
References/Resources
https://www.cms.gov/files/document/fy-2022-icd-10-cm-coding-guidelines-updated-02012022.pdf
