Small Intestinal Dilation Is Associated With Severe Abdominal Symptoms of Food-Protein-Induced Enterocolitis Syndrome in Adults.

BACKGROUND Food-Protein-Induced Enterocolitis Syndrome (FPIES) is a non-IgE-mediated food allergy that causes gastrointestinal symptoms, though its anatomical origin and pathogenesis remain unclear. Abdominal distention is common in adult FPIES, but symptoms vary among patients. This study aimed to establish objective criteria for assessing abdominal distention and to clarify the pathophysiology and anatomical origin of FPIES. METHODS This study targeted 26 adult FPIES patients. Abdominal distention was broken down into eight factors, and an evaluation algorithm was developed based on items with high positivity rates. Clinical characteristics, blood, and imaging analyses were performed before and after OFC (oral food challenge) to investigate the pathophysiology. RESULTS Among 14 adult FPIES patients who underwent OFC, seven showed positive results. The latency period was 1.5 h, with the most frequent symptoms being abdominal distention (100%), abdominal pain, and nausea (71.4%). All patients received treatment with intravenous extracellular fluid infusion and ondansetron, which resulted in reduced symptom duration. In an evaluation of blood test data, there were no specific serological markers of FPIES, except in the severe case. Image analysis with computed tomography revealed significant dilation and edema of the small intestine during the FPIES event, suggesting that dilation of the small intestine is associated with adult FPIES. CONCLUSION These results are expected to aid in the early and appropriate diagnosis of FPIES based on medical interviews, blood test data, and imaging findings when adult patients present to medical institutions with severe acute gastroenteritis symptoms.