the abdomen, nausea, vomiting, constipation or diarrhea, fever and leukocytosis. Most people with colonic diverticulosis are unaware of this structural change. When symptoms do appear in a person over 40 years of age it is important to obtain medical advice and exclude more dangerous conditions such as cancer of the colon or rectum. Segmental colitis associated with diverticulosis Segmental colitis associated with diverticulosis (SCAD) is a condition characterized by localized inflammation of the colon between diverticula (interdiverticular mucosa) while sparing the diverticular orifices. SCAD may lead to abdominal pain, especially in the left lower quadrant, intermittent rectal bleeding, and chronic diarrhea. Causes Diet The U.S. National Institutes of Health notes that, although the low-fiber theory of the cause of diverticulosis is the leading theory, it has not yet been proven. Genetics The predisposition to diverticulosis for specific individuals is likely explained by a genetic component, a theory that is supported by studies examining the rates of diverticulosis among twins. The heritability of diverticulosis is estimated to be approximately 40%. Intestinal motility Another theory suggests the degeneration of glial neurons in the myenteric plexus and the interstitial cells of Cajal lead to slowed intestinal movement and consequently fecal content exerts increased pressure on the colon wall resulting in the formation of diverticula. Risk factors Advanced age constipation a diet that is low in dietary fiber (although this claim is controversial) connective tissue disorders (such as Marfan syndrome and Ehlers Danlos Syndrome) that may cause weakness in the colon wall hereditary or genetic predisposition, extreme weight loss heavy meat consumption Pathophysiology The precise mechanisms by which diverticula are formed are unknown. Multiple theories have been proposed including genetic susceptibility, diet, intestinal motility, changes in the microbiome, and inflammation. One leading theory suggests that diverticula form in weakened areas of the colon wall that are subjected to increased pressure. The strength of the colon wall is known to decrease with age. Previous theories proposed that impacted fecal matter and certain foods would get stuck in diverticula (thereby causing trauma), which caused poor blood flow, death of the affected intestinal wall cells, and intestinal perforation. Newer theories have called this paradigm into question. Diagnosis Diverticulosis is defined by the presence of multiple pouches (diverticula) in the colon. In people without symptoms, these are usually found incidentally during other investigations. While a good history is often sufficient to form a diagnosis of diverticulosis or diverticulitis,