Using the Index, the Tabular List, and the Guidelines
Learn the required two-step lookup process, and the conventions that determine which codes may be reported together and in what order.
By the end of this lesson you can
- Use the Alphabetic Index and Tabular List in the correct order
- Apply Excludes1 and Excludes2 notes correctly
- Sequence a principal or first-listed diagnosis appropriately
- Explain why signs and symptoms are not coded alongside a confirmed diagnosis
Lesson Notes
Read through the key concepts before you try the challenge.
Never code from the index alone
You are coding under time pressure at Lakeside Medical Associates.
You look up 'bronchitis' in the Alphabetic Index, find a code, and submit it. It is denied. Had you turned to that code in the Tabular List, you would have seen an instructional note requiring an additional code, and an Excludes1 note that ruled out the code you chose given the patient's documented condition.
Your task: Build the two-step habit that the official guidelines require and that prevents this class of error entirely.
ICD-10-CM has two parts and both must be used. The Alphabetic Index is organized by condition and points you toward a code. The Tabular List is organized numerically and contains the actual code, along with the instructional notes that govern its use. The index never shows those notes, which is precisely why coding from it alone is unsafe.
The ICD-10-CM Official Guidelines for Coding and Reporting are published annually alongside the code set and are the authority for how codes are selected and sequenced. They are not optional guidance — HIPAA requires their use for reporting, and payers apply them.
Excludes1 and Excludes2
These two notes look almost identical and mean opposite things. Confusing them is one of the most consequential mistakes in diagnosis coding.
| Note | Means | Effect |
|---|---|---|
| Excludes1 | NOT CODED HERE — the two conditions cannot occur together | Never report both codes for the same encounter |
| Excludes2 | Not included here — the condition is separate but may coexist | Both codes may be reported together when both are documented |
The way to remember it: Excludes1 means mutually exclusive — one or the other, never both. Excludes2 means not part of this code, so if the patient has both conditions, code both. Payers apply Excludes1 edits automatically, so a claim carrying an Excludes1 pair is typically rejected without human review.
Deciding whether two codes may be reported together
A patient is documented with two related conditions. The Tabular List entry for the first carries an Excludes2 note naming the second. May both be coded?
- 1
Identify which Excludes note applies.
This is the whole decision, and it takes five seconds once you know to look. Excludes1 forbids reporting both; Excludes2 permits it. Reading the note carefully is the difference between a paid claim and a rejected one.
- 2
Confirm both conditions are documented independently.
Excludes2 permits both codes; it does not require them. You still need documentation supporting each condition separately. Coding a second condition because the note allows it, without documentation, is unsupported coding.
- 3
Report both codes, sequencing by the reason for the encounter.
The condition chiefly responsible for the visit is listed first. Sequence is not cosmetic — it drives medical necessity determinations and can affect payment and quality reporting.
- 4
If it had been Excludes1, choose the single code the documentation supports and query if genuinely ambiguous.
Excludes1 means the code set asserts these cannot coexist. Reporting both is a definite rejection. When the documentation truly seems to describe both, that is a question for the provider rather than a coding judgment.
Result: Both codes reported, correctly sequenced, each supported by documentation.
Excludes1 is mutually exclusive; Excludes2 permits coexistence. Always read the note in the Tabular List before reporting a pair of related codes.
Sequencing and the signs-and-symptoms rule
The first-listed diagnosis in the outpatient setting is the condition chiefly responsible for the services provided at that encounter. It is not necessarily the patient's most serious problem, and not necessarily the first one mentioned in the note.
The signs-and-symptoms rule follows from that. When a definitive diagnosis is established, code the diagnosis and not the symptoms that led to it — the symptoms are integral to it. When no definitive diagnosis is reached, code the symptoms, because that is what is actually known.
A patient presents with chest pain. After evaluation the provider documents 'chest pain, rule out angina.' What should be coded?
Challenge
Apply what you've learned in this lesson.
Work with the actual guidelines. CMS publishes the ICD-10-CM Official Guidelines for Coding and Reporting free each year.
- Find one Excludes1 note and one Excludes2 note in the Tabular List. Write out each, and explain in your own words what a coder may and may not do in each case.
- For an encounter documented as 'fatigue and weight loss, rule out malignancy,' decide what to code and write two sentences justifying it with reference to the guidelines.
- A note documents both type 2 diabetes and diabetic neuropathy. Look up how the code set expects that relationship to be reported, and explain what a combination code is.
- Describe the two-step lookup process in your own words, and state one specific thing you would miss by skipping the Tabular List.
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