Feasibility of a Minimally Invasive Diagnostic Algorithm in Suspected Crohn's Disease

Inclusion Criteria: * Clinical suspicion of CD\* * Age 18-40 years * Signed informed consent \*A clinical suspicion of CD is based on the following definition: * Diarrhea and/or abdominal pain for more than 1 month (or repeated episodes of diarrhea and/or abdominal pain) and either * fecal calprotectin ≥ 200 mg/kg or * fecal calprotectin ≥ 50 mg/kg plus one or more of the following findings: * C-reactive protein (CRP) \> 5 mg/L * Thrombocytosis (\> 400 x 109/L) * Anemia (hemoglobin \< 7.0 mmol/L for women and \< 8.0 mmol/L for men or a decrease \> 0.5 mmol/L compared to the usual level) * Prolonged fever (\> 37.5 ◦C for more than 2 weeks) * Weight loss (≥ 3 kg or ≥ 5% compared to the normal body weight) * Perianal abscess / fistula * Family history of inflammatory bowel disease. Exclusion Criteria: * Previous intestinal resection * Positive serologic markers for celiac disease * Positive stool polymerase chain reaction for pathogenic bacteria * Positive stool polymerase chain reaction for intestinal parasites * Suspected or established acute bowel obstruction (ileus) * Intake of NSAIDs or acetylsalicylic acid ≤ 4 weeks before inclusion, except low-dose, prophylactic acetylsalicylic acid (≤ 150 mg per day) * Intake of opioid or opioid-like medications ≤ 1 week before inclusion * Pregnancy or lactation * Inability to comply with protocol requirements, e.g. for reasons including alcohol or recreational drug abuse * Known gastrointestinal disorder other than functional gastrointestinal disorders * Renal failure defined by a plasma-creatinine above the normal reference range