M72.8 vs N13.6
M72.8 and N13.6 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 M72.8
perirenal fasciitis with infection (N13.6)
M72.8
Other fibroblastic disorders
Billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M70-M79
Use when the record says
- Abscess of fascia
- Fasciitis NEC
- Other infective fasciitis
Indexed under
- Abscess › fascia (connective tissue) (embolic) (fistulous) (infective) (metastatic) (multiple) (pernicious) (pyogenic) (septic)
- Contraction, contracture, contracted › fascia (s)
- Fasciitis › infective
- Fasciitis › specified NEC
- Fasciitis › traumatic
N13.6
Pyonephrosis
Billable
- Chapter 14
- Diseases of the genitourinary system
- Section
- N10-N16
Use when the record says
- Conditions in N13.0-N13.5 with infection
- Obstructive uropathy with infection
Indexed under
- Hydropyonephrosis
- Pyohydronephrosis
- Pyonephrosis
- Hydroureter › with infection
- Ormond's disease › with infection (with ureteral obstruction)
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