A39.1 vs E27.4
A39.1 and E27.4 can never be reported together. ICD-10-CM declares them mutually exclusive with an Excludes1 note, meaning the two conditions cannot occur in the same patient — so exactly one of them is correct for any given encounter.
The official note, declared on E27.4
Waterhouse-Friderichsen syndrome (A39.1)
A39.1
Waterhouse-Friderichsen syndrome
Billable
- Chapter 1
- Certain infectious and parasitic diseases
- Section
- A30-A49
Use when the record says
- Meningococcal hemorrhagic adrenalitis
- Meningococcic adrenal syndrome
Indexed under
- Friderichsen-Waterhouse syndrome or disease
- Waterhouse (-Friderichsen) syndrome or disease (meningococcal)
- Adrenalitis, adrenitis › meningococcal, hemorrhagic
- Apoplexia, apoplexy, apoplectic › adrenal
- Disease, diseased › Waterhouse-Friderichsen
E27.4
Other and unspecified adrenocortical insufficiency
Not billable
- Chapter 4
- Endocrine, nutritional and metabolic diseases
- Section
- E20-E35
These two codes sit in different chapters of the Tabular List, which is usually the clearest signal that they describe different underlying processes rather than different degrees of the same one.
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027