Gut
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Appendicectomy and smoking are environmental factors that are known to influence ulcerative colitis (UC). The phenotype of UC is different in patients with coexistent primary sclerosing cholangitis (PSC). This study investigates the interaction of appendicectomy and PSC on the epidemiology and clinical behaviour of colitis. ⋯ In contradistinction to UC, appendicectomy did not significantly influence the prevalence of the PSC groups, or the extent of colitis in PSC-IBD, but as with UC, did appear to delay their onset. The extensive milder colitis, which is characteristic of PSC-IBD, relates to other poorly understood factors. Further prospective studies are required to determine any influence of appendicectomy on the extent of colitis in IBD and an associated dysplasia or colorectal cancer.