ICD-10-CM Code First Notes · Chapter 1 · FY 2027 A00-B99

Code First Notes in Chapter 1: Certain infectious and parasitic diseases ICD-10-CM

A Code First note means the underlying condition named in the note is sequenced before this code. In Chapter 1 (A00-B99), notes printed in the chapter name other codes 27 times, and Code First Notes anywhere in the Tabular List name the chapter’s codes 81 times, covering 47 distinct codes, categories and ranges. Switch views to read the list either way.

✓ From the official FY 2027 ICD-10-CM Tabular ListDefinitions follow the Official Guidelines, Section I.A
27
References in Its Notes
81
References to Its Codes
47
Chapter Codes Named
A00-B99
Chapter 1
Chapter 1

Code First Notes by the code that carries the note

6 of 6 shown
  • A40 Streptococcal sepsis applies to 5 codes
    • , if applicable, postprocedural sepsis (T81.44-)
    • sepsis due to central venous catheter (T80.211-)
    • streptococcal sepsis during labor (O75.3)
    • streptococcal sepsis following abortion or ectopic or molar pregnancy (O03.37, O03.87, O04.87, O07.37, O08.82)
    • streptococcal sepsis following immunization (T88.0-)
    • streptococcal sepsis following infusion, transfusion or therapeutic injection (T80.22-, T80.29-)
  • A41 Other sepsis applies to 15 codes
  • A84.89 Other tick-borne viral encephalitis
    • , if applicable, transfusion related infection (T80.22-)
  • B20 Human immunodeficiency virus [HIV] disease
    • Human immunodeficiency virus [HIV] disease complicating pregnancy, childbirth and the puerperium, if applicable (O98.7-)
  • B39 Histoplasmosis applies to 7 codes
    • associated AIDS (B20)
  • B97.4 Respiratory syncytial virus as the cause of diseases classified elsewhere
    • otitis media (H65.-)
    • upper respiratory infection (J06.9)

The first view lists notes printed in this chapter (a note on a category or block applies to every code beneath it). The second lists codes of this chapter named by Code First Notes anywhere in the Tabular List, including notes in other chapters.

Questions About Code First Notes

What does a Code First note mean?

A Code First note means the underlying condition named in the note is sequenced before the code that carries the note. Under the etiology/manifestation convention, a “code first” note appears at the manifestation code and a “use additional code” note at the etiology code (Section I.A.13). The FY 2027 Tabular List has 810 of them; 600 name other codes, with 736 references to 429 distinct codes, categories and ranges.

Can a code with a Code First note be the principal diagnosis?

Not when it is a manifestation code. Codes titled “in diseases classified elsewhere” are never permitted as the first-listed or principal diagnosis; they must follow the underlying condition. The etiology and manifestation page lists them all.

Related References

ICD-10-CM Official GuidelinesICD-10-CM Code LookupICD-10-CM Codes ListCode Lists by Tag

Source: FY 2027 ICD-10-CM Tabular List (CMS and NCHS) and the ICD-10-CM Official Guidelines for Coding and Reporting FY 2027, Section I.A. ICD List is not affiliated with CMS or NCHS.