Excludes1 pair
N12 vs N20.9
N12 and N20.9 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on N12
calculous pyelonephritis (N20.9)
N12
Tubulo-interstitial nephritis, not specified as acute or chronic
Billable
- Chapter 14
- Diseases of the genitourinary system
- Section
- N10-N16
Use when the record says
- Interstitial nephritis NOS
- Pyelitis NOS
- Pyelonephritis NOS
Indexed under
- Pyonephritis
- Nephritis, nephritic › antitubular basement membrane NEC (tubulo-interstitial)
- Nephritis, nephritic › tubulo-interstitial (in)
- Pyelonephritis › nonobstructive
- Disease, diseased › antiglomerular basement membrane antibody › tubulo-interstitial nephritis
N20.9
Urinary calculus, unspecified
BillableUnspecified
- Chapter 14
- Diseases of the genitourinary system
- Section
- N20-N23
Indexed under
- Anuria › calculous (impacted) (recurrent)
- Calculus, calculi, calculous › anuria (impacted) (recurrent)
- Calculus, calculi, calculous › urinary (duct) (impacted) (passage) (tract)
- Stone › urinary (duct) (impacted) (passage)
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