- Autoimmune, genetic, and environmentally triggered elements
- Transmural bowel wall involvement
- Can affect anywhere in GI tract mouth-to-anus
- Smoking and appendectomy increase risk
- Northern Europeans and North Americans
- Peak onset ages 15-30
- Known crohns
- Rectal bleeding
- Chronic abd pain
- Sometimes oral/eye/joint sx
- Evidence of ulceration
- Sometimes abscess &/or fistulas in peri-rectal area