Guest Post: Improving the selection of a principal diagnosis

by Adrienne Commeree, CPC, CPMA, CCS, CEMC, CPIP

The selection of the principal diagnosis is one of the most important steps when coding an inpatient record. The diagnosis reflects the reason the patient sought medical care, and the principal diagnosis can drive reimbursement.

But while code selection may seem fairly straightforward in some cases, it can seem like throwing a dart at a board in others. Multiple factors must be considered and reviewed before a coder can assign a diagnosis as principal. There may be many reasons a patient went to the hospital, and multiple conditions may have been treated during that patient’s stay. Because of these complicating factors, relying solely on a software program to discern the principal diagnosis might lead to errors. A thorough review of the documentation, along with a solid understanding of the Official Guidelines for Coding and Reporting, instructional notes, and Coding Clinic issues, is imperative.

The ICD-10-CM Official Guidelines for Coding and Reporting state:

The circumstances of inpatient admission always govern the selection of principal diagnosis. The principal diagnosis is defined in the Uniform Hospital Discharge Data Set (UHDDS) as “that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care.”

The UHDDS collects data on patients related to race and ethnicity and is issued by the Centers for Disease Control and Prevention. Its definitions are used by acute care hospitals to report inpatient data elements that factor in the DRG classification system, which is how the hospital receives reimbursement for the inpatient admission.

Coders and CDI professionals must review all the documentation by the physician or any qualified healthcare practitioner who, per the coding guidelines, is legally accountable for establishing the patient’s diagnosis.

Parts of the medical record include the history and physical, progress notes, orders, consultation notes, operative reports, and discharge summary. While reading through a provider’s documentation, coders must ask themselves: “Is this condition requiring any diagnostic evaluation, therapeutic work, treatment, etc.?”

Once a medical record has been completely reviewed, coders must decide which code identifies the reason the patient was admitted and treated: What condition “bought the bed”?

But our work isn’t done after that. Are there any instructional notes or chapter-specific guidelines that give sequencing direction for coding? For example, if a patient is treated for decompensated diastolic congestive heart failure and also has hypertension, instructional notes within Chapter 9 of the ICD-10-CM manual, Diseases of the Circulatory System, give sequencing directives for the coding of these conditions.

“Decompensated,” according to Coding Clinic, Second Quarter 2013, indicates that there has been a flare-up (acute phase) of a chronic condition. I50.33 is the ICD-10-CM code for acute-on-chronic congestive heart failure. However, before assigning that code as the principal diagnosis, you must check the instructional notes directly under category I50 for heart failure. These notes, usually printed in red, give sequencing guidance for codes in this category.

Per the Official Guidelines for Coding and Reporting, “code first” informs coders that these conditions have both an underlying etiology and multiple body system manifestations due to that etiology:

“For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first, if applicable, followed by the manifestation. Wherever such a combination exists, there is a ’use additional code’ note at the etiology code, and a ‘code first’ note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.

To code for the hypertension, the instructional notes guide the coder to reference code I11.0 (hypertensive heart disease with heart failure). More instructional guidance following the code helps the coder correctly assign the principal diagnosis for this patient.

But we’re still not done. Are there any issues of Coding Clinic that give more information regarding the assignment of a principal diagnosis? In reference to the example above, congestive heart failure with hypertension, documentation guidelines for reporting these two conditions have changed for 2017.

The Third Quarter 2016 Coding Clinic reiterates the documentation requirements and sequencing by stating that “the classification presumes a causal relationship between hypertension and heart involvement.”

The preceding example is one of many. A coder can have more than one diagnosis that fits the definition of a principal diagnosis, or possibly two diagnoses that are contrasting (either/or). If there are no chapter-specific guidelines for sequencing (is the patient pregnant? Does the patient have an HIV-related illness?), then refer to Section II, subsections B, C, D, and E, in the ICD-10-CM coding guidelines.

Editor’s note: This article originally appeared in JustCoding. Commeree is a coding regulatory specialistat HCPro in Middleton, Massachusetts. Contact her at acommeree@hcpro.com. Opinions expressed are that of the author and do not necessarily represent HCPro, ACDIS, or any of its subsidiaries.