billion a year in the United States in 2013. Signs and symptoms Diverticulitis typically presents with lower quadrant abdominal pain of a sudden onset. Patients commonly have elevated C-reactive protein and a high white blood cell count. In North America and Europe the abdominal pain is usually on the left lower side (sigmoid colon), while in Asia it is usually on the right (ascending colon). There may also be fever, nausea, diarrhea or constipation, and blood in the stool. Complications In complicated diverticulitis, an inflamed diverticulum can rupture, allowing bacteria to subsequently infect externally from the colon. If the infection spreads to the lining of the abdominal cavity (the peritoneum), peritonitis results. Sometimes, inflamed diverticula can cause narrowing of the bowel, leading to an obstruction. In some cases, the affected part of the colon adheres to the bladder or other organs in the pelvic cavity, causing a fistula, or creating an abnormal connection between an organ and adjacent structure or another organ (in the case of diverticulitis, the colon, and an adjacent organ).Related pathologies may include: Bowel obstruction Peritonitis Abscess Fistula Bleeding Strictures Causes The causes of diverticulitis are poorly understood, with approximately 40 percent due to genes and 60 percent due to environmental factors. Conditions that increase the risk of developing diverticulitis include arterial hypertension and immunosuppression. Obesity is another risk factor. Low levels of vitamin D are associated with an increased risk of diverticulitis. Diet It is unclear what role dietary fiber plays in diverticulitis. It is often stated that a diet low in fiber is a risk factor; however, the evidence to support this is unclear. There is no evidence to suggest that the avoidance of nuts and seeds prevents the progression of diverticulosis to an acute case of diverticulitis. In fact, it appears that a higher intake of nuts and corn could help to avoid diverticulitis in adult males. Pathology Right-sided diverticula are micro-hernias of the colonic mucosa and submucosa through the colonic muscular layer where blood vessels penetrate it. Left-sided diverticula are pseudodiverticula, since the herniation is not through all the layers of the colon. Diverticulitis is postulated to develop because of changes inside the colon, including high pressures because of abnormally vigorous contractions. Diagnosis People with the above symptoms are commonly studied with computed tomography, or a CT scan. Ultrasound can provide preliminary investigation for diverticulitis. Amongst the findings that can be seen on