What can go wrong?
Diverticula are almost always innocent bystanders, and their presence is termed uncomplicated diverticular disease. Despite this, colonic diverticula can occasionally become the source of serious illness. These few may bleed or perforate thus becoming complicated diverticular disease.
Diverticulitis – For unknown reasons, a diverticulum, usually in the left colon, can become inflamed (diverticulitis) and sometimes burst leaking bacteria-rich feces into the abdominal cavity (peritoneum). The result is usually confined to the surface of the adjacent colon producing an acute, sometimes devastating illness characterized by severe abdominal pain in the left lower part of the abdomen, fever and prostration. The treatment usually consists of fluids, bed rest, and antibiotics. Some cases require hospital admission.
Sometimes the infection fails to be localized along the colon wall and an abscess occurs. Patients with a pelvic or abdominal abscess are very ill, and the abscess fluid (pus) must be drained through a large needle directed by a radiologist, or sometimes by a surgeon. In very severe cases, the colon above the abscess is brought out to the skin by a surgeon and the intestinal contents are temporarily collected in a bag. This is called a colostomy. Later, when the infection has settled down, the affected colon is removed and the colon rejoined.
Rarely, there may be free perforation of intestinal contents into the peritoneum. Peritonitis is life threatening and requires emergency surgery. Also rarely, a severe attack of diverticulitis may cause a narrowing of the colon that causes an obstruction. It also rarely may cause a passage from one segment of the colon to the small bowel, bladder, vagina, or skin. The latter phenomenon is called a fistula. These complications are rare and should not concern those who have uncomplicated diverticula.
Diverticular hemorrhage – As described above, diverticula follow the paths of the arteries as they penetrate the muscle layer of the colon wall. Uncommonly, these same arteries can erode through the thin wall of the diverticulum and cause a major hemorrhage. This usually occurs when a person is elderly. The earliest symptoms are faintness and the appearance of much bright red blood by rectum.
Such a complication requires hospitalization and blood transfusion. Colonoscopy is sometimes attempted to localize the site of the bleeding, but is technically difficult. Angiography may also be done. In this procedure dye that can be detected by x-ray is injected into the arteries of the intestines. If the bleeding is active, some dye may be seen leaking into the colon. While diverticulitis almost always involves the left or sigmoid colon, most diverticular bleeding occurs in the right side of the colon.
Fortunately, the bleeding usually stops spontaneously, but recurs in about one-quarter of cases. Infrequently, a surgeon must operate to remove the segment of the colon containing the bleeding diverticulum.