Approximately 16% of ulcerative colitis (UC) patients will have a colectomy within 10 years of their diagnosis of UC. Due to the high morbidity and mortality associated with colectomy procedures, clinicians and patients strive to avoid surgery. The decline of colectomy rates over the last 6 decades has been mainly attributed to advances in medical management of UC. Clostridium difficile infection and colorectal neoplasia have also been associated with driving the risk of colectomy. This dissertation focuses on describing the effect of C. difficile and colorectal neoplasia on the risk of colectomy for UC patients. Chapters 2 and 3 establish the cumulative risk of acquiring C. difficile infection after the diagnosis of UC and demonstrated that C. difficile infections increase the short- and long-term risk of colectomy. Further, both Chapters 2 and 3 demonstrate that C. difficile infections increased the risk of postoperative complications following colectomy for UC. Chapter 4 demonstrate that the incidence of colectomy for colorectal dysplasia and cancer has remained stable over time, and showed that the observed decrease in colectomy rates is most likely due to a decrease in colectomies from medically refractory disease. Finally, Chapter 5 determined the cost-effectiveness of different surveillance colonoscopy intervals for colorectal dysplasia among a subgroup of inflammatory bowel disease (IBD) patients with a higher risk of developing colorectal dysplasia and cancer; i.e., patients with IBD and primary sclerosing cholangitis (PSC).