K31 ICD-10-CM Code: Other diseases of stomach and duodenum

K31 is the ICD-10-CM diagnosis code for other diseases of stomach and duodenum. K31 sits in the ICD-10-CM chapter for diseases of the digestive system (k00-k95), within the section covering diseases of esophagus, stomach and duodenum (k20-k31).

Header codes like K31 cannot be reported on claims directly, they organize child codes that share clinical context but the actual diagnosis must be coded to the highest level of specificity supported by the documentation. Coders should look at K31's child codes and select the one that matches the patient's documented presentation, since payers reject header codes submitted as the primary diagnosis. For risk adjustment workflows, header codes never contribute to a Medicare Advantage member's RAF score on their own; only billable child codes that happen to map to a payment HCC affect risk-adjusted plan payments.