ICD-10 Code B81.1 – Intestinal capillariasis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code B81.1 – Intestinal capillariasis
What it is
Intestinal capillariasis is a parasitic infection of the small intestine caused by Capillaria species. It can lead to chronic intestinal inflammation and malabsorption.
Clinical signs
Clinical features vary; refer to documentation. Reported findings may include chronic diarrhea, abdominal pain, weight loss, and signs of poor nutrient absorption.
When to use this code
Use B81.1 when the provider documents intestinal capillariasis, intestinal Capillaria infection, or a confirmed diagnosis of this parasitic disease. Code it when the record identifies the intestinal site rather than a nonspecific parasitic infection. Check documentation if the organism or location is unclear.
Do not use for
Do not use this code for other helminth infections, nonspecific diarrhea, or suspected parasitic disease without confirmation. If the chart names a different parasite, code that condition instead.
Coding tip
Verify the provider’s documented organism and site before assigning B81.1.