K55.021 vs P77
K55.021 (Focal (segmental) acute infarction of small intestine) compared with P77 (Necrotizing enterocolitis of newborn), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.
Can these codes be reported together?
No — do not report together. K55.021 carries an Excludes1 note covering P77: “necrotizing enterocolitis of newborn (P77.-)”
Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
Side by side
| K55.021Focal (segmental) acute infarction of small intestine | P77Necrotizing enterocolitis of newborn | |
|---|---|---|
| Billing status | Billable | Non-billable header |
| Classification | K00-K95 — Diseases of the Digestive System (K00-K95) | P00-P96 — Certain Conditions Originating in the Perinatal Period (P00-P96) |
| Definition | Focal (segmental) acute infarction of small intestine is a billable ICD-10-CM diagnosis code (K55.021). | Necrotizing enterocolitis of newborn is a non-billable ICD-10-CM category code (P77). |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources