Small bowel capsule endoscopy (SBCE) has become an important tool in clinical practice since its introduction in 2000. This non-invasive method allows the visualization of small bowel mucosa, being essential in the management of many conditions, such as suspected small bowel bleeding, inflammatory bowel diseases and intestinal polyposis syndromes. Despite recommendations concerning SBCE in different pathologies, there are still some technical concerns to be addressed. The optimal preparation for SBCE has been one of these controversial issues.

Currently, the European Society of Gastrointestinal Endoscopy (ESGE) recommends that patients ingest a purgative agent (2L of polyethylene glycol, PEG) and antifoaming agents for SBCE, because it was associated with a better visualization. However, it remains unclear which is the optimal timing for purgative use. Furthermore, the use of a booster agent after capsule ingestion is already performed in colon capsule endoscopy, but less is known about its application in SBCE. Also, it remains to be clarified whether a better visualization results in higher diagnostic yield and impacts patients' outcomes.

Therefore, the global aim of this prospective, randomized, multi-centric study is to determine the optimal timing and preparation for small-bowel capsule endoscopy (regardless of the equipment used), comparing four groups of different preparation protocols:

• Protocol 1) 1L of Moviprep® solution the night before the procedure
• Protocol 2) 1L of Moviprep® solution up to 2h before the procedure
• Protocol 3) 0.5L of Moviprep® solution up to 2h before the procedure plus 0.5L of Moviprep® solution after the capsule had reached the duodenum (assessed with real-time viewer)
• Protocol 4) 1L of Moviprep® solution after the capsule had reached the duodenum (assessed using real-time viewer)

Inclusion Criteria:

• Be 18 years old or older
• Present OGIB (either occult or overt)
• Agree with study's procedures and have signed the informed consent for the study and SBCE, prior to SBCE procedure

Exclusion Criteria:

• Patients performing capsule endoscopy in urgent setting for overt obscure GI bleeding
• Inpatients or bedridden
• History of surgery of the esophagus, stomach, small bowel, or colon
• History of abdominal or pelvic radiation therapy
• Suspected or confirmed stenosis or occlusion
• Suspected or confirmed bowel perforation
• Severe comorbidities, as defined by grade 3 "severe decompensation" in the Adult Comorbidity Evaluation-27 index (ACE-27)
• Pregnant women
• Patients using narcotics or prokinetics in the week before the SBCE