Pathology/Lab Coding Alert

These pathology examples will help you follow guidelines and code-level instruction.

Getting ICD-10-CM codes in the correct order on a claim can be as important as picking the correct code(s). In fact, code sequencing can impact patient care, as well as whether a claim gets paid.

Context: Although pathologists often assign diagnosis codes based on findings from cytology or histopathology exams, clinical labs must report current ICD-10-CM codes narrated by the ordering physician. Either way, diagnosis coding errors can result in lack of “medical necessity” for a procedure,

Tip 1: Remember the Reasons Why

Clinically, the diagnosis code sequence can alert the provider to conditions that will influence patient care. “The code sequence paints a hierarchical picture of the patient’s condition, as the underlying causes and relationship(s) between diseases and symptoms are expressed by way of the codes’ place in the lineup,” says Jan Blanchard, CPC, CPMA, consultant at Vermont-based Physician’s Computer Company (PCC).

Payment: Improper code order can also affect your bottom line. “Correct sequencing avoids denials,” says JoAnne M. Wolf, RHIT, CPC, CEMC, coding manager at Children’s Health Network in Minneapolis. Plus, code sequence can affect medical necessity required for coverage. “Some payers will only look at the first diagnosis code or the first few listed diagnosis codes when assigning benefits,” says Wolf.

Quality: Many quality programs such as Medicare’s Merit-based Incentive Payment System (MIPS) rely on proper diagnosis coding. Errors now could impact future pay for your pathology practice.

Tip 2: Stick to the Basics

To get the diagnosis code order right on your claims, you need to stick with the basics. That means your initial code selection is always the reason for the encounter or the final diagnosis. But you need to pay attention to any guidance from the ICD-10-CM manual about that first code choice.

Do this: Look at the ICD-10-CM manual index first, then turn to the tabular list. “So long as you always consult the tabular section of your ICD-10-CM manual, you’ll never wonder if you’re working with a code for which sequencing rules need to be applied,” Blanchard says.

Remember: You also need to be familiar with the ICD-10-CM guidelines. Often, instructions appear in one place, but aren’t repeated by each code. “Everything needs to be read together. There is no such thing as remembering everything and knowing what to code without looking at the notes and the guidelines,” according to Sharon J. Oliver, CPC, CDEO, CPMA, CRC, AAPC Approved Instructor, coding consultant and owner of Medical Coding & Consultants in Jonesborough, Tennessee, at the beginning of her HEALTHCON Regional 2022 presentation.

Tip 3: Understand Etiology and Manifestation

When the patient has a condition that is a manifestation of an underlying disease, you need to code the underlying disease (etiology) first, and the manifestation second. You’ll find that instruction in ICD-10-CM Official Guidelines, Section 1.A.13.

In addition to the guidelines, ICD-10-CM provides direction at the code level to enforce this hierarchy. You’ll find the instruction as Code first, Use additional code, and In diseases classified elsewhere notes in the Tabular section of ICD-10-CM. “‘Use additional’ is the requirement that the underlying condition be sequenced first followed by manifestation(s),” says Blanchard.

Example: The pathologist examines a skin biopsy for a patient diagnosed with AIDS. Based on microscopic morphology, the pathologist diagnoses the biopsy as Kaposi’s sarcoma. When you look at the tabular listing for Kaposi’s sarcoma, you’ll see the instruction “Code first any human immunodeficiency virus [HIV] disease.” The tabular listing for HIV states, “Use additional code(s) to identify all manifestations of HIV infection.”

That means you should code the diagnosis in this case as B20 (Human immunodeficiency virus [HIV] disease) followed by C46.0 (Kaposi’s sarcoma of skin).

Caveat: If ICD-10-CM does not specify a sequence among the codes in question, then you should align the diagnosis codes with the reasons for the visit. If the pathologist examined a toenail specimen diagnosed with a dermatophyte (fungal) infection for an HIV patient, you would code B35.1 (Tinea unguium), which includes dermatophytosis of nail. Without a Code first note, you don’t need to list the HIV infection first.

Tip 4: Master ‘With,’ ‘See,’ ‘Excludes’

When you look up a condition in the ICD-10-CM Alphabetic Index, you may see a term directly following the word such as “with,” “in,” or “see.” Once you turn to the tabular list, you’ll get additional direction from “excludes” notes. All of these words give you some further information that may impact your code choice and sequencing.

For instance: The physician orders a creatinine test, indicating the patient has hypertension and stage 2 chronic kidney disease (CKD), but does not indicate if the conditions are related. Do you report more than one diagnosis code as the ordering diagnosis, and if so, in what order?

Answer: Guideline I.C.9.a explains that the classification of hypertension “presumes a causal relationship between hypertension and … kidney involvement, as the two conditions are linked by the term ‘with’ in the Alphabetic Index. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated.” When you turn to “hypertension” in the index and follow the “with” to “kidney,” that brings you to I12.9 (Hypertensive chronic kidney disease with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease). And when you turn to that code in the tabular list, you’ll see the note to “use additional code to identify the stage of chronic kidney disease.” Because the physician indicated stage 3, you should sequence N18.2 (Chronic kidney disease, stage 2 (mild)) as the second diagnosis code.

Excludes1 example: A clinician orders a glucose test for a patient with type 2 diabetes and hyperglycemia. Do you code both conditions as the ordering diagnosis, and, if so, in what order?

Do this: The alphabetic index leads you to R73.9 (Hyperglycemia, unspecified) when you look up hyperglycemia. But when you turn to the code in the tabular list, you’ll find this note: “Excludes1: diabetes mellitus (E08-E13).” Once you turn to those codes, you’ll find the appropriate coding for this lab order is E11.65 (Type 2 diabetes mellitus with hyperglycemia), not R73.9 plus a separate code for diabetes.