Chapter17: INTESTINES:Sigmoid Diverticulitis

Question 1

In general, diverticular disease refers to what?

Answer 1

acquired pseudo-diverticular outpouchings of the colonic mucosa and submucosa.

Question 2

What is the prevalence of colonic diverticula?

Answer 2

Such colonic diverticula are rare in persons under age 30, but the prevalence approaches 50% in Western adult populations over age 60.

Question 3

What is diverticulosis ?

Answer 3

Diverticulae are generally multiple and the condition is referred to as diverticulosis.

This disease is much less
common in Japan and nonindustrialized tropical countries,probablybecause of dietary
differences

Question 4

What is the pathogenesis of Colonic diverticula?

Answer 4

Colonic diverticula result from the unique structure of the colonic muscularis propria and
elevated intraluminal pressure in the sigmoid colon.

Where nerves, arterial vasa recta, and their
connective tissue sheaths penetrate the inner circular muscle coat, focal discontinuities in the
muscle wall are created.

In other parts of the intestine these gaps are reinforced by the external longitudinal layer of the muscularis propria, but, in the colon, this muscle layer is gathered into the three bands termed taeniae coli.

Increased intraluminal pressure is probably due to
exaggerated peristaltic contractions,with spasmodic sequestration of bowel segments, and may
be enhanced by diets low in fiber, which reduce stool bulk, particularly in the sigmoid colon.

Question 5

WHat is the anotomic morphology of colonic diverticula?

Answer 5

Anatomically, colonic diverticula are:

• small,
• flask-like outpouchings,
• usually 0.5 to 1 cm in diameter,
• that occur in a regular distribution alongside the taeniae coli ( Fig. 17- 40A ).

These are most common in the sigmoid colon, but more extensive areas may be
affected in severe cases.

Question 6

Why is colonic diverticula may be missed on casual inspection?

Answer 6

Because diverticulae are compressible, easily emptied of fecal contents, and often surrounded by the fat-containing epiploic appendices on the surface of the colon, they may be missed on casual inspection.

Question 7

What is the appearance of colonic diverticula?

Answer 7

Colonic diverticula have a thin wall
composed of a flattened or atrophic mucosa, compressed submucosa,andattenuated or,
most often, totally absent muscularis propria ( Fig. 17-40B , C).

Hypertrophy of the circular
layer of the muscularis propriain the affected bowel segment is common.

Question 8

Obstruction of
diverticulae leads to inflammatory changes, producing what?

Answer 8

diverticulitis and peri-diverticulitis.

Question 9

What is the reason for the perforation in colonic dierticulae?

Answer 9

Because the wall of the diverticulum is supported only by the muscularis mucosa and a thin
layer of subserosal adipose tissue, inflammation and increased pressure within an obstructed
diverticulum can lead to perforation.

With or without perforation, diverticulitis may cause
segmental diverticular disease–associated colitis, fibrotic thickening in and around the colonic
wall, or stricture formation.

Perforation can result in pericolonic abscesses, sinus tracts, and, occasionally, peritonitis.

Question 10

Answer 10

FIGURE 17-40 Sigmoid diverticular disease.

• A, Stool-filled diverticula are regularly arranged
• B, Cross-section showing the outpouching of mucosa beneath the muscularis propria.
• C, Low-power photomicrograph of a sigmoid diverticulum showing protrusion of the mucosa and submucosa through the muscularis propria

Question 11

What are the clinical features of individuals with diverticular disease?

Answer 11

• remain asymptomatic throughout their lives,
• and the lesions are most often discovered incidentally.
• About 20% of those affected develop manifestations of disease including
  
  • intermittent cramping,
  • continuous lower abdominal discomfort,
  • constipation,
  • distention,
  • and a sensation of never being able to completely empty the rectum.
• Patients sometimes experience alternating constipation and diarrhea.
• Occasionally there may be minimal chronic or intermittent blood loss, or, in extremely rare cases, massive hemorrhage.

Longitudinal studies have shown that diverticulae can regress early in their development or, more commonly, become more numerous and prominent over time.