The European guidelines currently recommend to use 2 L of polyethylene glycol and free residue diet before any capsule endoscopy. However, up to now, no studies have been conducted to specifically evaluate bowel preparation modalities before small bowel capsule endoscopy in patients with Crohn's disease.

In patients with Crohn's disease and small bowel ulcers, polyethylene glycol may remove some fibrin from these ulcers and alter bowel preparation. Moreover, it is important to select the most acceptable bowel preparation because patients with Crohn's disease will have to repeat capsule endoscopy several times after initiating treatment, for monitoring under treatment, or for detection of post-operative recurrence.

In a preliminary retrospective study, it has been suggested that a simplified bowel preparation with liquid diet the evening before and water on the morning of the capsule endoscopy induced a better bowel preparation than the standard method with polyethylene glycol.

Thus, the aim of the study is to demonstrate the superiority of this simplified bowel preparation compared to the standard preparation modality in terms of quality of bowel preparation, patient's acceptability and diagnostic yield.

Crohn's disease is a chronic inflammatory bowel disease characterized by the presence of ulcers that can affect the entire digestive tract, from the mouth to the anus. The existence of small bowel lesions is pejorative and associated with poorer outcomes and a higher risk of intestinal resection.

Small bowel capsule endoscopy allows the visualization of the entire small bowel in a non-invasive and outpatient setting, without any anesthesia. It is the exam with the best diagnostic yield for the detection of small bowel ulcers in patients with Crohn's disease. Moreover, it allows the monitoring of patients after initiating treatment to assess mucosal healing and the detection of post-operative recurrence.

As for any endoscopic examinations, its acceptability depends on bowel preparation modalities. The European Society of Gastrointestinal Endoscopy (ESGE) currently recommends to use 2 L of polyethylene glycol and free residue diet before any capsule endoscopy. However, patients with Crohn's disease were a minority (< 1.5 %) in the studies on which these guidelines are based on.

Yet, in patients with small bowel Crohn's disease, polyethylene glycol may remove some fibrin from the ulcers and hence, alter bowel preparation. Moreover, it is important to select the most acceptable bowel preparation because patients with Crohn's disease will have to repeat capsule endoscopy several times after initiating treatment, for monitoring under treatment, or for detection of post-operative recurrence.

A preliminary retrospective study suggested that a simplified bowel preparation with liquid diet the evening before and water on the morning of the capsule endoscopy induced a better bowel preparation than the standard method with polyethylene glycol.

Thus, the aim of CROHN-PREP study is to demonstrate the superiority of this simplified bowel preparation compared to the standard preparation modality in terms of quality of bowel preparation, patient's acceptability and diagnostic yield.

Inclusion Criteria:

• Patients of both genders aged over 18 years old
• With an established diagnosis of Crohn's disease, whether active or quiescent
• With an indication of a small bowel capsule endoscopy
• Without any small bowel stricture (patency capsule procedure on the 7 days before the capsule endoscopy)
• Registered with a social security scheme
• Having provided their oral consent for the study after appropriate information

Exclusion Criteria:

• - Patients aged below 18 years old
• Diagnosis of ulcerative colitis or IBD unclassified
• Presence of an ileostomy
• Presence of a small bowel syndrome
• Symptoms suggestive of a small bowel stricture
• Retention of the patency capsule on an abdominal X-ray performed 48 hours after the ingestion
• Abdominal pain after the ingestion of the patency capsule
• Planned abdominal surgery in the next month
• Known intestinal fistula
• Swallowing disorders
• Established diagnosis of delayed gastric emptying or suggestive symptoms
• Intake of non-steroidal anti-inflammatory drugs (NSAIDs) in the month prior to the capsule endoscopy
• Intake of oral iron supplementation in the week prior to the capsule endoscopy
• Intake of oral 5-ASA granules in the week prior to the capsule endoscopy
• Ongoing pregnancy
• Presence of a pace-maker or implantable defibrillator
• Known allergy to polyethylene glycol or to lactose
• Vulnerable people i.e. adults under a legal protection regime (guardianship, trusteeship, judicial safeguard)

Single blind