Ulcerative colitis (UC) is an inflammatory bowel disease progressing through flare-ups. The therapeutic objective, which was originally based on clinical remission, is currently evolving with the development of biotherapies towards the achievement of endoscopic remission. Current recommendations for therapeutic management advocate the achievement of endoscopic mucosal healing (EMH), with an observed decrease in the necessity for colectomy in the case of EMH. Endoscopic evaluation of the severity of UC is performed during a digestive endoscopy (colonoscopy for a complete colonic exploration, or recto-sigmoidoscopy for a partial exploration of the colon) from endoscopic activity scores adapted for UC.

Currently, the score the most commonly used is the MAYO endoscopic score. This is a global score of increasing intensity from 0 to 3, taking into account the following basic lesions: vascular pattern, granularity or/and friability of the mucosa, spontaneous bleeding, erosion and ulceration. However this score has limits: it does not distinguish deep cavitating ulcerations with mucous detachment from simple ulcerations which have a better prognosis.

A new endoscopic score specific for UC has been developed and is currently being validated. It is termed Ulcerative Colitis Endoscopic Index of Severity (UCEIS). This evaluation takes into account the three most reproducible factors - the vascular pattern, the presence of bleeding, and erosions or ulcerations including cavitating ulceration - in the total score.

To ensure optimal patient care and an adaptation of the therapeutic medical care to the endoscopic severity of the disease, endoscopic exploration should be performed recurrently. However, this exploration is an invasive procedure, requires general anaesthesia for colonoscopy, and can lead to potential complications such as perforation. This explains the poor acceptance by patients, resulting in a sub-optimal therapeutic support.

For each patient, the study will be conducted in accordance with the following schedule:

Information/inclusion visit: D-30 (± 30 days)

• Full information about the trial
• Verification of inclusion and non-inclusion criteria
• Acquisition of informed consent (either the same day or after a period of reflexion)
• Medical and surgical history
• Clinical examination

Endoscopic visit: D0 On two consecutive days or within a maximum of seven days but obligatorily before the anti-Tumor Necrosis Factor (TNF) alpha treatment

• Faecal sample (calprotectin)

• Clinical examination

• Endoscopic examination by PillCamCOLON (C2) then by conventional endoscopy (colonoscopy)

  -The endoscopic examinations will each be analyzed by a different endoscopist working in a blinded evaluation. An UC activity score will be calculated depending on two scores: MAYO and UCEIS.

• Notification of Adverse Event (AE) / Serious Adverse Event (SAE)

Follow-up visit: W12 (12 weeks ± 5 days after D0)

• Faecal sample (calprotectin)

• Clinical examination

• Endoscopic examination by PillCamCOLON (C2) then by conventional endoscopy (coloscopy)

  -The endoscopic examinations will each be analyzed by a different endoscopist working in a blinded evaluation. An UC activity score will be evaluated depending on two scores: MAYO and UCEIS.

• Notification of AE/SAE

End-of-study visit (possibly by telephone) W14 (± 5 days)

*Notification of AE/SAE

Inclusion Criteria:

• Male or female patient between 18 and 70 years old
• Patient with UC requiring treatment with anti-TNFalpha or vedolizumab
• Patient affiliated to a social security scheme
• Patient able to understand and follow the study instructions
• Patient having signed an informed consent form

Exclusion Criteria:

• Patient with severe and acute colitis
• Patient with Crohn's disease or non-classified colitis
• Patient with an indication for surgical management of UC
• Patient with a history of sub-total or total colectomy, or with colostomy or ileostomy.
• Patient with a history of intestinal irradiation
• Patient with a known or suspected intestinal stricture
• Patient with clinical signs suggestive of intestinal stricture
• Patient with dysphagia with choking on solid food or swallowing disorders
• Patient with a contra-indication for an anti TNFalpha treatment
• Patient with a contra-indication for conventional endoscopy (colonoscopy or recto-sigmoidoscopy)
• Patient with congestive heart failure or severe renal impairment
• Patient with a pacemaker or other implanted electronic medical device
• Patient participating in another interventional clinical trial
• Pregnant or nursing woman
• Vulnerable individuals: persons deprived of liberty, under tutelage or guardianship