Crohn's disease (CD) is a form of inflammatory bowel disease that can affect any part of the digestive system. Symptoms of this chronic illness include abdominal pain, bloating, nausea, vomiting, and diarrhea. CD also causes bowel wall ulcers, strictures (narrowings of a hollow structure due to scar tissue and swelling), and fistulae (abnormal passages from the intestines to another organ or to the skin).