K55 vs P77

K55 (Vascular disorders of 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 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

	K55Vascular disorders of intestine	P77Necrotizing enterocolitis of newborn
Billing status	Non-billable header Report instead: K55.011, K55.012, K55.019, K55.021, K55.022	Non-billable header Report instead: P77.1, P77.2, P77.3, P77.9
Classification	K00-K95 — Diseases of the Digestive System (K00-K95)	P00-P96 — Certain Conditions Originating in the Perinatal Period (P00-P96)
Definition	Vascular disorders of intestine is a non-billable ICD-10-CM category code (K55).	Necrotizing enterocolitis of newborn is a non-billable ICD-10-CM category code (P77).

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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources