Many patients with diverticular disease have no symptoms at all. Some patients may have abdominal pain, diarrhoea, or change in the bowel habits. Occasionally, there may be bleeding. Diverticulitis -- an infection of the diverticula -- may cause pain, fever and change in bowel habits. More severe symptoms can occur with complications such as perforation, abscess, or fistula formation (connection between the large intestine with another organ).