Introduction

The global burden of Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn’s disease (CD), is increasing. Due to its chronic nature, IBD entails long-term healthcare resource use, contributing to substantial economic and environmental costs. Digestive endoscopy, while a cornerstone of disease monitoring, is associated with high energy consumption, greenhouse gas (GHG) emissions, and medical waste. Intestinal ultrasound (IUS) has emerged as a non-invasive, accurate, and potentially more sustainable alternative.

Aims & Methods

The present study aimed to compare the environmental impacts in terms of CO₂ emissions, energy consumption (kWh), and disposable waste of IUS and endoscopy for therapeutic monitoring in IBD. In this single-center, retrospective observational study conducted at IRCCS Humanitas Research Hospital (Rozzano, Milan), all consecutive IUS and lower gastrointestinal endoscopies performed for therapeutic monitoring in IBD patients between January 2022 and December 2025 were included. Procedures for oncologic surveillance in long-standing disease, isolated rectal involvement (<15 cm from the anal verge), or without confirmed IBD were excluded. Clinical and procedural data were collected. Environmental metrics such as CO₂ emissions, energy consumption (kWh), and disposable waste were estimated using validated conversion factors and compared using appropriate statistical tests (Independent-samples t-test or Mann–Whitney U test).

Results

Endoscopic procedures performed during study period (n=2698) ↓ Exclusion criteria - Endoscopic procedures in trial setting (n=1157) -Endoscopic surveillance in UC (n= 216) -Pouchoscopies & ulcerative proctitis monitoring (n=162) - Operative/ emergency procedures (n=71) ↓ Endoscopic procedures included in the analysis (n=1092) Colonoscopies (n= 710)↵ ↳ Sigmoidoscopies (n=382)

intestinal ultrasounds performed during study period (n=1541) ↓ Exclusion criteria - Indications other than disease monitoring/ patient BMI> 30 Kg/m2 (n= 231) ↓ Intestinal ultrasounds included in the analysis (n=1310) ​

Flowchart 1. Visual representation of the process of selecting procedures to be included in the final analysis. UC: Ulcerative colitis; BMI: Body Mass Index.

During the study period, a total of 1092 endoscopic procedures, comprising 710 colonoscopies and 382 sigmoidoscopies, along with 1310 IUS were performed in 1028 IBD patients (58% UC, 42% CD). Estimated resource use for all endoscopic procedures totaled 1,256 kWh of electricity, 72,080 L of CO₂ emissions, and 585.6 kg of disposable waste, based on procedural averages (~1.5 kWh, 80 L of CO₂, 650 g waste per colonoscopy; ~50% of values for sigmoidoscopies). In contrast, IUS was associated with an estimated 524 kWh of electricity and 196.5 kg of disposable waste (average ~0.4 kWh, almost no CO₂ consumption, 150 g waste per exam). Compared to endoscopy, IUS reduced energy use by 82%, CO₂ emissions by 95%, and waste generation by 66% (P < 0.05 for all comparisons).

Conclusion

While gastrointestinal endoscopy remains indispensable in certain clinical scenarios, its environmental impact is considerable. In contrast, IUS emits almost no equivalent of CO₂, consumes significantly less energy per examination and produces negligible wastes. For therapeutic monitoring in IBD, IUS has demonstrated high diagnostic accuracy with a markedly lower ecological footprint. These findings promote IUS as a sustainable and environmentally friendly alternative for routine IBD monitoring in appropriate scenarios.

Disclosure

A Armuzzi has received consulting and/or advisory board fees from AbbVie, Allergan, Amgen, Arena, Biogen, Bristol-Myers Squibb, Celltrion, Eli-Lilly, Ferring, Galapagos, Gilead, Janssen, MSD, Mylan, Pfizer, Protagonist Therapeutics, Roche, Samsung Bioepis, Sandoz, Takeda, lecture and/or speaker bureau fees from AbbVie, Amgen, Arena, Biogen, Bristol-Myers Squibb, Celltrion, Eli-Lilly, Ferring, Galapagos, Gilead, Janssen, MSD, Mitsubishi Tanabe, Novartis, Pfizer, Roche, Sandoz, Takeda, Tigenix, and research grants from MSD, Pfizer, Takeda and Biogen. A Repici received consulting fee from Medtronic, Fuji and Olympus and has received research grant from Alfa Sigma, Norgine, Boston and Erbe. C Bezzio received speaker’s fees and consulting fees from for Takeda, MSD, Ferring, Abbvie, Galapagos and Janssen. A Dal Buono has received speaker’s fees from Pfizer, MSD, Eli-Lilly, Celltrion, Janssen, and consulting fees from Ferring. R Gabbiadini has received speaker’s fees from Pfizer, MSD, Ferring, Eli-Lilly, Celltrion, Janssen, consulting fees from Pfizer and Abbvie. G. Privitera has received speaker’s fees from Janssen and Alphasigma. B. Masoni and G. Franchellucci declare no conflict of interests.

Introduction

A reduction of bowel wall thickness (BWT) on intestinal ultrasound (IUS) is an early predictor of endoscopic response in ulcerative colitis (UC).¹ Shear-wave elastography (SWE) may offer additional prognostic information.

Aims & Methods

We aimed to identify early IUS parameters predicting treatment response to filgotinib, a selective JAK-1 inhibitor. This prospective observational study included UC patients with endoscopically active disease starting on filgotinib 200 mg daily. IUS parameters, including SWE, were assessed at baseline (T0), week 4 (T1) and at second endoscopy (T2). The endoscopic Mayo score (EMS) was assessed at T0 and at T2 in both the most-affected segment and the sigmoid. Endoscopic response was defined as a decrease in EMS of at least 1 point.

Results

A total of 23 patients were included. 10 patients were female (10/23, 44%), the mean disease duration was 14.4 years (SD±10.4), and 14 patients (14/23, 61%) had failed 2 or more biologics. Endoscopic response was observed in 6 of the 21 patients (29%) who underwent a second endoscopy after a median of 14 weeks (IQR 12-17). The submucosal thickness in the sigmoid decreased significantly more between T0 and T1 in endoscopic responders compared to non-responders (-40±23.9% vs -11.5±24.5%, p=0.022). At T1, a BWT decrease of ≥1.33 mm or ≥24.7% (OR 32.5 [2.38-443.15], p=0.009 and OR: 13.8 [1.21-156.6], p=0.035) and a submucosal thickness decrease of ≥20.8% (OR: 13.8 [1.21-156.6], p=0.035) predicted endoscopic response at T2. Additionally, improvement in Colour Doppler Signal (CDS) at T1 predicted endoscopic response (OR: 20.0 [1.66-241.7], p=0.018). SWE values in the sigmoid at T0, T1 and T2 were not significantly different between endoscopic responders and non-responders in the sigmoid. While the change in SWE values at T2 compared to baseline was significantly different between the two groups (9.9± 11.5 kPa vs. -8.1 ± 11.4 kPa, p=0.002), the difference at T1 was not significant and did not predict endoscopic response in the sigmoid (OR: 1.07 [0.99-1.16], p=0.088).

Logistic regression for endoscopic response (EMS ≥1 decrease) based on IUS B-mode parameters at week 4 (T1) in the sigmoid	Univariable Odds ratio (95% CI)	P-value
BWT (per mm increase)	0.34 [0.99-1.17]	0.087
BWT (per % increase)	0.97 [0.92-1.01]	0.118
BWT decrease ≥1.33 mm	32.5 [2.38-443.15]	0.009
BWT decrease ≥ 24.72%	13.8 [1.21-156.6]	0.035
Submucosa (per % increase)	0.95 [0.89-1.00]	0.049
Submucosa decrease ≥20.76%	13.8 [1.21-156.6]	0.035​
CDS (per one category increase)	0.26 [0.09-0.77]	0.015
CDS (≥1 decrease in mLimberg classification)	20.0 [1.66-241.7]	0.018
CDS (mLimberg of 0)	28.0 [1.99-394.4]	0.014

Conclusion

On IUS, BWT, submucosal thickness and CDS predict endoscopic response after four weeks of filgotinib treatment. SWE values in the sigmoid changed differently among endoscopic responders and non-responders, but did not predict treatment response.

References

1. de Voogd FA et al. Early Intestinal Ultrasound Predicts Clinical and Endoscopic Treatment Response and Demonstrates Drug-Specific Kinetics in Moderate-to-Severe Ulcerative Colitis. Inflamm Bowel Dis 2023. DOI: 10.1093/ibd/izad274.

Disclosure

MP: none;
CT: none;
FV: received speaker’s fees from AbbVie, Pfizer and Takeda;
RJ: none,
ML: Consultancy/lecture fees from Abbvie, Bristol Myers Squibb, Eli Lilly, Galapagos, Janssen-Cilag, Johnson & Johnson, Medtronic, Pfizer, Takeda, Tillotts. Grants received from Alfasigma, NFU transformation deal, ZonMW and TKI.
RG: received speakers free from Janssen-Cilag BV and Pfizer Inc.
GD: has served as advisor for AbbVie, Abivax, Alimentiv,, Astrazeneca, Bristol Meiers Squibb, Boehringer Ingelheim, Celltrion, Eli Lilly, , GlaxoSmithKline, Johnson and Johnson, Merck Sharp Dome, Pfizer, Polpharm, Sanofi, Takeda, Tillotts, and received speaker fees from AbbVie, Eli Lilly, Johnson and Johnson, Merck Sharp Dome, , Pfizer, Takeda, Tillotts,.
KG: KB Gecse has received grants from AbbVie, Pfizer Inc, Celltrion and Galapagos; consultancy fees from AbbVie, Arena Pharmaceuticals, ImmunicTherapeutics, Janssen Pharmaceuticals, Novartis, Pfizer Inc., and Takeda and speaker’s honoraria from Abbvie, Celltrion, Eli Lilly, Ferring, Janssen Pharmaceuticals, Pfizer Inc, Takeda and Tillotts.

Introduction

Ulcerative colitis (UC) is a chronic inflammatory bowel disease where accurate assessment of disease activity is essential for effective patient management. Endoscopy is the gold standard for evaluating mucosal inflammation, but non-invasive alternatives, such as transabdominal ultrasound (TAUS), are garnering interest.

Aims & Methods

This study aimed to evaluate the sensitivity of rectal wall thickness measurements using TAUS in assessing disease activity in ulcerative colitis, and to identify an ideal cut-off threshold by comparing results with endoscopic and histological findings.
In a prospective, observational study, we enrolled consecutive patients with UC who were referred to our tertiary center from May 2024 to April 2025. Eligibility required a scheduled TAUS within 30 days of a staging colonoscopy, without intervening therapy adjustments. Exclusion criteria included technically inadequate TAUS readings (e.g., due to anatomical variations or excessive gas interposition) and minor-aged patients. Each patient underwent TAUS performed by a single, experienced operator. A second experienced operator blind assessments were recorded to evaluate inter-observer variability. Rectal wall thickness was measured and compared with clinical, laboratory (CRP, fecal calprotectin), and endoscopic (MAYO score) indicators of disease activity. Histological status (active/inactive) and additional clinical data, including disease duration, extent, and therapy, were recorded.

Results

A total of 74 patients were analyzed, of whom 51.4% were female, with a median age of 55 years (IQR: 42–68). The majority presented with left-sided colitis (Montreal E2, 62.2%), followed by extensive colitis (E3, 25.7%) and proctitis (E1, 12.1%). The median disease duration was 12 years (IQR 5–23). Patients with an endoscopic MAYO score of 0 or 1 had a median rectal wall thickness of 4.95 mm (IQR 4.5–5.88), while those with a score of 2 or 3 had a median of 6.15 mm (IQR 5.3–6.7; p=0.003). Receiver Operating Characteristic (ROC) analysis for TAUS rectal wall thickness showed good discriminatory ability for endoscopic activity (cut-off: 5.55 mm, AUC 0.725, 95CI 0.597-0.853, Se 0.80, Sp 0.71), comparable to fecal calprotectin (cut-off: 277 µg/g, AUC 0.717, 95CI 0.589-0.845, Se 0.70, Sp 0.66; p=0.256) and superior to CRP (cut-off: 1 mg/L, AUC 0.511, 95CI 0.357-0.664, Se 0.50, Sp 0.50; p<0.0001). For histological activity, TAUS again performed well (cut-off: 5.55 mm, AUC 0.794, 95CI 0.682-0.906, Se 0.76, Sp 0.80), closely matching fecal calprotectin (cut-off 302, AUC 0.744, 95CI 0.627-0.861, Se 0.69, Sp 0.73; p=0.425) and outperforming CRP (cut-off 1.5, AUC: 0.631, 95CI 0.497-0.765, Se 0.62, Sp 0.63; p<0.0001). Inter-observer agreement for TAUS rectal wall thickness was excellent, with an intraclass correlation coefficient of 0.923 (p<0.0001), underscoring the reproducibility of this non-invasive method.

Conclusion

TAUS measurement of rectal wall thickness demonstrates promising sensitivity and reproducibility in detecting mucosal and histological activity in UC, aligning closely with established markers such as fecal calprotectin. A cut-off value of 5.55 mm showed good discriminatory performance in this cohort, suggesting potential utility as a non-invasive marker of disease activity..Given its non-invasive nature, low cost, and strong inter-observer agreement, TAUS is a valuable adjunct for routine UC monitoring. Combined with clinical and biochemical data, it may reduce the need for repeated endoscopy, minimizing patient burden, healthcare costs, and environmental impact.