Complications of Crohn's disease may be related or unrelated to the inflammation within the intestine. Intestinal complications of Crohn's disease include obstruction and perforation of the small intestine or colon, abscesses (collections of pus), fistulae, and intestinal bleeding. Massive distention or dilatation of the colon (megacolon) and rupture (perforation) of the intestine are potentially life-threatening complications. Both may require surgery, but, fortunately, these two complications are rare. Recent data suggest that there is an increased risk of cancer of the small intestine and colon in patients with long-standing Crohn's disease, but studies are conflicting.