Sustainable monitoring in inflammatory bowel disease: comparative carbon, energy, waste, and cost impact of intestinal ultrasound versus colonoscopy

Background: Treat-to-target strategies in inflammatory bowel disease (IBD) rely on repeated objective assessments, leading to frequent colonoscopy for therapeutic decision-making. Although effective, endoscopic monitoring is resource-intensive and may not be necessary in all stable patients. Aims: To evaluate the environmental and economic impact of intestinal ultrasound (IUS) compared with colonoscopy for therapeutic monitoring in IBD. Methods: In this single-center retrospective cohort (2022-2024), 200 adults with IBD undergoing both IUS and colonoscopy were analyzed. The functional unit was one monitoring episode. For each modality, we quantified carbon dioxide equivalent emissions (CO₂e), energy use (kWh), and disposable waste (g) within defined system boundaries. Procedure cost was assessed as a secondary outcome. A patient-level model projected cumulative impact across ten monitoring cycles, comparing an IUS + fecal calprotectin (FCP >250 μg/g) strategy with colonoscopy-for-all. Results: Per procedure, colonoscopy required +0.91 kWh, emitted +2.9 kg CO₂e, and generated +212 g disposables versus IUS (all p<0.001). IUS reduced energy use by ∼95%, CO₂e by ∼100-fold, and disposables by ∼85%. Over ten cycles, an IUS-first strategy reduced cumulative CO₂e emissions and costs by ∼40% (both p<0.05). Conclusions: IUS substantially lowers environmental and economic burden compared with colonoscopy while supporting timely therapeutic decisions. An IUS + FCP-first approach represents a pragmatic, sustainable monitoring strategy in IBD.