BACKGROUND AND AIMS: Our aim was to determine if transabdominal intestinal ultrasound changes after 48±24h of intravenous corticosteroids can predict treatment outcomes in hospitalized patients with severe ulcerative colitis.

METHODS: We performed a blinded observational multicenter study. Ultrasound parameters were assessed before treatment initiation, after 48±24h, and 6±1 days. Treatment response was determined within seven days by two outcome measures: 1) Partial Mayo score reduction, 2) No administration of rescue therapy.

RESULTS: Out of sixty-nine recruited patients, fifty-six were included in the final analysis, with thirty-seven responders. The colon segment with the highest baseline bowel wall thickness was analyzed, being the sigmoid in all patients. There was no difference in baseline bowel wall thickness between responders and non-responders in the partial Mayo score outcome. At 48±24h, a significant difference between responders and non-responders was identified in both absolute bowel wall thickness (median 3.1mm vs 4.9mm; p<0.0001), absolute reduction (-1.9mm vs -0.2mm; p<0.001), and relative reduction (-35.9% vs -4.1%; p<0.0001). A ≤20% reduction had a sensitivity of 84.2% (95%CI 60.4, 96.6%) and a specificity of 78.4% (61.8, 90.2%) for determining non-response (area under the curve 0.85). In the multivariable analysis, a >20% reduction had the highest odds ratio (22.6 (4.2, 201.2), p=0.001) for determining response. Similar results were seen for the rescue therapy outcome.

CONCLUSIONS: Changes in bowel wall thickness after 48±24h following intravenous corticosteroid treatment in hospitalized patients with severe ulcerative colitis identify responders with high accuracy and might be used as an early marker to guide accelerated rescue therapy.