Most people have small pouches in their colons that bulge out through weak spots. A pouch is called a diverticulum, and multiple pouches are called diverticula. This condition is called diverticulosis. When pouches become infected or inflamed, the condition is called diverticulitis. The cause of this disease is unknown, but it is believed that the association of a diet not containing sufficient fiber which contributes to constipation, makes the muscles strain to move stool that is too hard, causing increased pressure in the colon. This pressure instigates the weak spots in the colon to bulge out and become diverticula. Symptoms for diverticulitis and diverticulosis differ. Most people with diverticulosis do not have any discomfort or symptoms. However, symptoms may include mild cramps, bloating, and constipation. The most common symptom of diverticulitis is abdominal pain, with tenderness around the left side of the lower abdomen. Diverticulitis can be a source of rectal bleeding. If an infection is the cause, fever, nausea, vomiting, chills, cramping, and constipation may occur as well. The severity of symptoms depends on the extent of the infection and complications. Diverticulitis can lead to complications such as infections, perforations or tears, blockages, or bleeding. These complications always require treatment to prevent them from progressing and causing serious illness. Treatment may include open or laparoscopic surgery. A colostomy is infrequently needed unless it is an emergency.