NIMBUS study protocol: a single-centre feasibility study of non-invasive monitoring with bowel ultrasound in paediatric inflammatory bowel disease.

Introduction: Incidence of inflammatory bowel disease (IBD) is increasing in childhood and treatment increasingly targets mucosal healing. Monitoring bowel inflammation requires endoscopy or MRI enterography which are invasive, expensive and have long waiting lists.We aim to examine the feasibility of a non-invasive monitoring tool-bowel ultrasound (BUS)-in children with IBD and explore correlations with inflammatory markers and disease activity measures. Some BUS criteria have been found to correlate with these markers; however, this has not been validated in children.We aim to examine the feasibility of BUS for monitoring inflammation in this population; highlighting useful parameters for this purpose. We aim to inform a larger scale randomised controlled trial using BUS.

Methods And Analysis: This prospective observational feasibility study will be carried out over 24 months at the Noah's Ark Children's Hospital for Wales, Cardiff; with the endpoint recruitment of 50 participants. Children aged 2-18 years with a modified Porto criteria diagnosis of IBD will be included.Patients without IBD or who have previously undergone IBD-related surgery will be excluded; as will families unable to give informed consent.Ultrasound scan images and reports will be collected, as well as laboratory results and clinical outcomes.The primary aim will assess the feasibility of targeted BUS for disease monitoring; including recruitment statistics. The secondary aims will involve data collection and correlation analysis for targeted ultrasound parameters, biomarkers, disease activity scores and prediction of changes in treatment. The statistical methods will include: feasibility metrics, descriptive statistics, cross-tabulation and χ analysis, correlation analysis, regression analysis.

Ethics And Dissemination: Ethical approval is granted by NHS Research Ethics Committee. The sponsor is Cardiff and Vale University Health Board. We will publish the results in a peer-reviewed medical journal.

Trial Registration Number: NCT05673278.