Case #04 Discussion:

Diagnostic Options:

• Abdominal CT
• Colonoscopy
• Barium Enema

Impression: Diverticulosis.

Diverticulosis

The presence of colonic diverticula is rare in patients less than 30 years of age. However, the incidence increases with age as diverticula are present in 75% of people over 80. Diverticulosis is associated with the Western Industrial Revolution (1880) and the advent of milling wheat flour and low fiber diets.

The etiology of diverticular disease involves two basic mechanisms: raised intraluminal pressure and weakness of the colonic wall. Low fiber diets lead to increased intraluminal pressure and increased motor activity through excessive segmental contractions. Diverticula are herniations of mucosa through the colon where arterioles penetrate the muscular wall. This can occasionally cause massive bleeding.

Diverticular disease can be divided into three phases. The first or prediverticular phase consists of marked thickening of the muscular layers of the colon wall. The second phase (diverticulosis) is characterized by diverticula. The third phase (diverticulitis) occurs if and when a diverticulum perforates.

Evidence for Diverticular Disease

The most striking pathologic feature of diverticular disease using barium enema is marked thickening of the muscular bowel wall. This often appears as a narrowed colonic lumen by a series of indentations creating a saw-tooth pattern. This is most frequently seen in the sigmoid colon as it has the narrowest lumen of the colonic segments and intraluminal pressure is inversely proportional to luminal diameter.

On barium enema, diverticula appear as smooth oval or rounded protrusions ranging from several millimeters to several centimeters in diameter. They maybe completely or partially filled with barium. Partially filled diverticula often appear as ring shadows and may easily be confused with polyps. Diverticula can easily be distinguished from polyps if they are shown to be partially filled with barium or if they project beyond the margin of the bowel. Reliable differentiation from a polyp can be made if even a thin crescent of barium is within a diverticulum.

Complications of Diverticulosis

• Massive GI bleeding
• Diverticulitis

Imaging modalities to confirm the diagnosis of diverticulitis include:

• CT - test of choice. Helpful in staging degree of complications and evaluation of other diseases.
• Ultrasonography can reveal thickened, hypoechoic inflamed colonic wall, as well as abscesses and diverticula.
• Contrast Enema -- for mild-to-moderate cases of diverticulitis or when the diagnosis is in doubt. It carries the risk of spreading infection by extravasation through perforated diverticula. Only water-soluble contrast should be used, as barium combined with feces produces a more severe peritonitis.
• Endoscopy - offers little information in acute diverticulitis. Contraindicated as it increases risk of pericolic contamination.