This research study will evaluate if specific blood, stool and MRI tests can tell the difference between bowel wall inflammation without scarring and bowel wall inflammation with scarring that can cause bowel blockages requiring surgery.

This multi-center study will test the accuracy of individual and combined MRI and blood-based diagnostic tools in both children and adults with small bowel CD. We will determine the accuracy of a composite tool (including its multiple individual biomarkers) for defining the relative amounts of intestinal inflammation versus scarring in patients at the time of surgery (B2 disease) and in patients at an early stage of disease prior to complications (B1 disease).

Inclusion Criteria:

• Aim 1 (CD participants)

  1. Aged 8-70 years
  2. Undergoing first surgical distal (ileal) small bowel resection for structuring (B2 phenotype) Crohn's disease as determined by CTE or MRE or ileocolonoscopy
  3. English speaking

• Aim 2 (CD participants)

  1. Age 8 to 70 years
  2. Uncomplicated inflammatory small bowel CD based on clinical CTE or MRE or ileocolonoscopy performed within 6 months prior to enrollment (CD participants only)
  3. English speaking

• Aim 2 (Control participants)

  1. Age 8 to 70 years
  2. English speaking

Exclusion Criteria:

• Aim1 (CD participants)

  1. B1 or B3 (i.e., fistula, abscess, phlegmon/inflammatory mass) CD phenotype
  2. Prior small bowel surgery, including but not limited to surgical resection, stricturoplasty, or endoscopic treatment of a small bowel stricture
  3. Anything to eat or drink within 4 hours of study visit (participants may take their required medications with a little water)
  4. Known pregnancy (Note: Institutional policies/procedures will be followed for pregnancy screening)
  5. Contraindication for MRI (e.g., surgical implant, claustrophobia). Note: To be determined based on local procedures.

• Aim 2 (CD participants)

  1. Stenotic ileocecal valve at colonoscopy
  2. Prior small bowel surgery, including but not limited to surgical resection, stricturoplasty, or endoscopic treatment of a small bowel stricture
  3. Anything to eat or drink within 4 hours of study visit (participants may take their required medications with a little water)
  4. Known pregnancy (Note: Institutional policies/procedures will be followed for pregnancy screening)
  5. Contraindication for MRI (e.g., surgical implant, claustrophobia). Note: To be determined based on local procedures.

• Aim 2 (Control participants)

  1. Any known gastrointestinal tract disease
  2. Any known inflammatory/autoimmune disease involving another organ system (e.g., rheumatoid arthritis, scleroderma, multiple sclerosis).
  3. Fecal calprotectin level of ˃100 mcg.gm will be excluded from further analysis and replaced.

Aim 1 - Children and adults undergoing surgical small bowel resection for structuring CD; Aim 2 - children and adults that have known uncomplicated inflammatory small bowel CD (B1phenotype) AND healthy non-IBD participants