Prospective multicenter interventional non-randomized cross-sectional study. Ultrasound operators will be blinded to clinical and endoscopic findings and the endoscopist will be blinded of the clinical and ultrasound findings.

This study aims to develop novel imaging and molecular biomarkers of fibrosis, through the use of intestinal ultrasound and shear wave elastography, using histologic specimens obtained by endoscopic biopsies as reference standard.

Inclusion Criteria:

• Adult, 18 years of age and older,
• Established diagnosis (> three months) of ulcerative colitis,
• Performing colonoscopy, according to current standards of care and ECCO guidelines,
• Ability to understand and comply with the study procedure and sign an informed consent form

Exclusion Criteria:

• Pregnancy,
• presence of ascites, active infections, any contraindication to colonoscopy (e.g. intolerance to preparation, severe flare),
• inability to undergo intestinal ultrasound within the time set by the study,
• poor quality of ultrasound imaging (due to luminal gas or body habitus), or a diagnosis of malignancy in the pathological specimen.
• subjects who needs to change therapy

Ultrasound and endoscopy will be performed within 7 days in blinded fashion, where the ultrasound operators will be blinded to clinical and endoscopic findings and the endoscopist will be blinded of the clinical and ultrasound findings.