ICD-10 Code K55.31 – Stage 1 Necrotizing Enterocolitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code K55.31 – Stage 1 necrotizing enterocolitis
What it is
K55.31 identifies stage 1 necrotizing enterocolitis, an early suspected form of bowel inflammation and injury seen mainly in newborns. Use it when documentation specifically states stage 1 disease.
Clinical signs
Clinical features vary; refer to documentation. Notes may include feeding intolerance, abdominal distension, gastric residuals, or nonspecific systemic concern, but stage 1 findings are often early and not definitive.
When to use this code
Use this code when the provider documents stage 1 necrotizing enterocolitis, suspected NEC, or an equivalent early-stage diagnosis. It is appropriate for neonatal records where the condition is being actively evaluated and recorded as stage 1. If the chart only says abdominal distension or rule-out NEC, check documentation.
Do not use for
Do not use it for confirmed advanced necrotizing enterocolitis or for vague gastrointestinal symptoms without a documented stage 1 diagnosis. Check documentation if the note describes another bowel disorder.
Coding tip
Code from the provider’s stated stage, not from your clinical impression or suspected severity.