According to the website OrganizedWisdom, when fecal matter becomes caught in the colon (a condition known as fecal impaction), the backup that occurs exerts pressure on the walls of the organ. When this pressure becomes too great, it can stretch the colon and ultimately cause small tears or ruptures. Fecal impaction can be caused by extreme constipation or by certain conditions that can cause damage to the nerves around the colon. These diseases include Hirschprung's disease (which is a congenital problem that affects infants), Chagas disease (caused by the parasite trypansoma cruzi) and megacolon (which can be caused by infection from the bacteria C. dificile).
Another condition that can cause rupture of the colon is colon cancer. Colon cancer occurs when small growths (known as polyps) begin to divide more rapidly than normal. The tumors then can cause the rupture of the organ by causing swelling and pressure, which can also lead to fecal impaction. In addition, because colon tumors grow abnormally, they can weaken the its walls and cause detachment of the colon from some of the supportive tissue that helps strengthen its walls.
One cause of a ruptured colon is a condition known as diverticulosis. Diverticulosis is a condition in which small parts of the colon become wrapped around blood vessels, muscle, or the organ itself, causing the blood flow to that portion of the colon to be cut off. As a result, that part of the colon becomes weak and eventually die, which can cause it to rupture. Finally, ulcerative colitis, which is a disorder in which the immune system attacks the healthy tissue of the large intestine, can cause colonic rupture. Ulcerative colitis causes the membrane of the colon to become worn down--which, if severe enough, can cause a complete break in the large intestine, leading to a ruptured colon.