Sequencing Encephalopathy: Do not be Fooled by Documentation of “due to.”

Someone recently asked on LinkedIn if they must always sequent a UTI as the principal diagnosis when encephalopathy due to a urinary tract infection (UTI) is documented.

I disagree with this advice and here is why:

Coding Conventions and Guidelines

As discussed in the first article in this series, it is not necessary to link metabolic encephalopathy to the underlying infection e.g., the UTI. When this documentation occurs, some may overgeneralize the assignment of the principal diagnosis coding guideline that the condition after study is sequenced as the principal diagnosis. However, we cannot ignore other applicable coding conventions and guidelines. General Coding Guidelines 2.4 Signs and Symptoms states,

Codes that describe symptoms and signs, as opposed to diagnoses, are acceptable for reporting purposes when a related definitive diagnosis has not been established (confirmed) by the provider. Chapter 18 of ICD-10-CM, Symptoms, Signs, and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified (codes R00.0 – R99) contains many, but not all, codes for symptoms p. 13).

Guideline 2.18 Use of Signs/Symptoms/Unspecified Codes states,

“While specific diagnosis codes should be reported when they are supported by the available medical record documentation and clinical knowledge of the patient’s health condition, there are instances when signs/symptoms or unspecified codes are the best choices for accurately reflecting the healthcare encounter. Each healthcare encounter should be coded to the level of certainty known for that encounter. . . If a definitive diagnosis has not been established by the end of the encounter, it is appropriate to report codes for sign(s) and/or symptom(s) in lieu of a definitive diagnosis p. 17).”

Chapter Specific Guideline C.18 Symptoms, signs, and abnormal clinical and laboratory findings, not elsewhere classified (R00-R99) states this chapter includes symptoms, signs, etc., regarding which no diagnosis classifiable elsewhere is recorded. It also reiterates that symptoms codes, “are acceptable for reporting purposes when a definitive diagnosis has not been established (confirmed) by the provider p. 75).

Reporting a Definitive Diagnosis

Providers will often document that a patient is being admitted for altered mental status (AMS, code R41.82), which is a symptom code. Based on the above-mentioned guidelines, CDI professionals should look for evidence in the health record for a definitive diagnosis associated with altered mental status, which as discussed in prior articles is likely to be metabolic encephalopathy, toxic encephalopathy, or acute delirium.

Encephalopathy is a definitive diagnosis that is always due to another condition.

Assigning the Principal Diagnosis

But should acute (metabolic or toxic) encephalopathy be the principal diagnosis? If the associated diagnosis is metabolic encephalopathy, my opinion is yes. But the sequencing of toxic encephalopathy is more complicated.

Coding conventions (contained within Section 1 of the ICD-10-CM Official Guidelines for Coding and Reporting), which include instructional notes, supersede coding guidelines including assignment of the principal diagnosis. Although most coding is performed electronically, compliant coding requires consulting the alphabetic index and the tabular list before assigning a code. The tabular list includes instructional notes that are necessary for accurate code assignment.

The entry for encephalopathy in the alphabetic index includes an option for metabolic, which leads to G93.41 in the tabular list. Under metabolic, there are entries for drug induced and toxic, both of which take you to G92.8 in the tabular list.

• At the category level, G93 Other disorders of brain, there are no general instructional notes.
• The subcategory of G93.4 includes metabolic encephalopathy as well as encephalopathy, unspecified and other encephalopathy. At this level there is an Exclude2 note, which means the condition can also be coded, if appropriate.
• Regarding metabolic encephalopathy (G93.41), there are no instructional notes or other general or chapter specific instructions related to sequencing.

In contrast, when coding toxic encephalopathy the sequencing of toxic encephalopathy due to drugs is based on whether the drug toxicity qualifies as an adverse effect or poisoning.

• When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug (T36–T50). The code for the drug will have a fifth or sixth character 5 (e.g., T36.0x5-) to indicate adverse effect. There is an “use additional code” note at both other toxic encephalopathy (G92.8) and unspecified toxic encephalopathy (G92.9).
• If the toxic encephalopathy is due to a poisoning from a toxic agent, a code from categories T51–T65 is assigned first to identify the causative toxic agent. A code first note is at both of the toxic encephalopathy codes.

Therefore, when it comes to reporting toxic encephalopathy if it is due to poisoning it will not be the principal diagnosis. If it is due to an adverse effect, it may be the principal diagnosis if it meets the definition for reporting.

Sequencing Metabolic Encephalopathy due to a UTI

But my focus for this article is sequencing metabolic encephalopathy due to a UTI. If we look at code N39.0 for UTI, site not specified in the tabular list, we see an instructional note to use additional code to identify the infectious agent. There is also an Excludes1 note (do not code together) that does not include AMS, delirium, or encephalopathy.

Since there are no coding conventions that apply to the sequencing of these two diagnoses, let us look at the definition of a principal diagnosis and its associated guidelines. The Uniform Hospital Discharge Data Set (UHDDS) defines it as the “condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care (p. 107).”

In my opinion if the physician states the reason for the admission is AMS, which is clarified as metabolic encephalopathy, then metabolic encephalopathy should be the principal diagnosis regardless of the cause.

What if the provider does not clearly indicate the reason for the admission? Some CDI and coding professionals will apply guideline II.C Two or more diagnoses that equally meet the definition for principal diagnosis, which states,

“In the unusual instance when two or more diagnoses equally meet the criteria for principal diagnosis as determined by the circumstances of admission, diagnostic workup and/or therapy provided, and the Alphabetic Index, Tabular List, or another coding guidelines does not provide sequencing direction, any one of the diagnoses may be sequenced first (p. 108).”

Even if the provider does not specifically state the patient is admitted for AMS, UTIs do not usually require inpatient admission. It should be rare that a UTI is the reason for an inpatient admission. More often than not, UTI is an incidental finding but was not the primary focus of the workup even though it receives treatment. The UTI must be treated to address the associated metabolic encephalopathy. Additionally, documentation of metabolic encephalopathy due to UTI is irrelevant to the sequencing since there are no applicable instructional notes at either diagnosis or is it required by the definition of the principal diagnosis which talks about the condition after study. The condition that was studied was AMS, a symptom, and it was clarified into the definitive diagnosis of metabolic encephalopathy.

It is also important to note that the AHA Coding Clinic specifically addressed how to sequence encephalopathy due to UTI in the 2^nd Qtr. 2018 (p. 22) that the sequencing is based on the condition found after study to be responsible for the hospital admission. A trick I used to help identify the principal diagnosis is by asking what condition must be resolved prior to discharge. Will a patient be sent home with a UTI? Yes. Will a patient be sent home with acute metabolic encephalopathy? No. Therefore, clinically, the reason for the admission is the metabolic encephalopathy.

Why this sequencing is so confusing is that encephalopathy is a diagnosis made through the process of elimination. This is why a head CT is often performed on patients who present with acute AMS, to determine if it could be related to a structural cause that will appear on imaging like a stroke. A head CT is not indicated for a UTI, nor is an EEG, if performed, or any of the other diagnostic tests used to determine the cause of AMS. If the metabolic encephalopathy is secondary to the UTI, it should improve after a period of antibiotics. Again, the point at which the patient is usually discharged is when the patient’s metal status returns to baseline, not with the UTI is resolved.

My best advice for those who have an inpatient claim with metabolic encephalopathy due to UTI is to look for evidence of sepsis as this diagnosis will support an inpatient admission for a UTI. It would also likely be sequenced as the principal diagnosis assuming it is present on admission, which solves the sequencing issue.