Diverticulosis

Causes

Diet

The U.S. National Institutes of Health notes that, although the low-fiber theory of the cause of diverticulosis is the leading theory, it has not yet been proven.

Genetics

The predisposition to diverticulosis for specific individuals is likely explained by a genetic component, a theory that is supported by studies examining the rates of diverticulosis among twins. The heritability of diverticulosis is estimated to be approximately 40%.

Intestinal motility

Another theory suggests the degeneration of glial neurons in the myenteric plexus and the interstitial cells of Cajal lead to slowed intestinal movement and consequently fecal content exerts increased pressure on the colon wall resulting in the formation of diverticula.

Risk factors

1. Advanced age
2. constipation
3. a diet that is low in dietary fiber (although this claim is controversial)
4. connective tissue disorders (such as Marfan syndrome and Ehlers–Danlos syndrome) that may cause weakness in the colon wall
5. hereditary or genetic predisposition,
6. extreme weight loss
7. heavy meat consumption

Pathophysiology

The precise mechanisms by which diverticula are formed are unknown. Multiple theories have been proposed including genetic susceptibility, diet, intestinal motility, changes in the microbiome, and inflammation. One leading theory suggests that diverticula form in weakened areas of the colon wall that are subjected to increased pressure. The strength of the colon wall is known to decrease with age. Previous theories proposed that impacted fecal matter and certain foods would get stuck in diverticula (thereby causing trauma), which caused poor blood flow, death of the affected intestinal wall cells, and intestinal perforation. Newer theories have called this paradigm into question.

Diagnosis

Diverticulosis is defined by the presence of multiple pouches (diverticula) in the colon. In people without symptoms, these are usually found incidentally during other investigations.

While a good history is often sufficient to form a diagnosis of diverticulosis or diverticulitis, it is important to confirm the diagnosis and rule out other pathology (notably colorectal cancer) and complications.

Imaging

• Barium enema is inferior to colonoscopy in terms of image quality and is usually only performed if the patient has strictures or an excessively tortuous sigmoid colon where colonoscopy is difficult or dangerous.
• Colonoscopy will show the diverticulum and rule out malignancy. A colonoscopy should be performed 4–6 weeks after an acute episode.
• Contrast CT is the investigation of choice in acute episodes of diverticulitis and where complications exist.
• MRI provides a clear picture of the soft tissue of the abdomen, however, its expense often outweighs the benefits when compared to contrast CT or colonoscopy.
• Plain abdominal X-ray may show signs of a thickened wall, ileus, constipation, small bowel obstruction or free air in the case of perforation. Plain X-rays are insufficient to diagnose diverticular disease.
• There is no blood test for diverticulosis.

It is important to note that both barium enema and colonoscopy are contraindicated during acute episodes of diverticulitis, as the barium may leak out into the abdominal cavity, and colonoscopy can cause perforations of the bowel wall.

Management

Many people with diverticulosis have minimal to no symptoms and do not require any specific treatment. Colonic stimulants should be avoided. Treatments, like some colon cleansers, that cause hard stools, constipation, and straining, are not recommended.

Diet

A high-fiber diet and fiber supplements are advisable to prevent constipation. The American Dietetic Association recommends 20–35 grams each day. Wheat bran has been shown to reduce intra colonic pressure.

The US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says foods such as nuts, popcorn hulls, sunflower seeds, pumpkin seeds, caraway seeds, and sesame seeds have traditionally been labeled as problem foods for people with this condition; however, no scientific data exists to prove this hypothesis. The seeds in tomatoes, zucchini, cucumbers, strawberries, raspberries, and poppy seeds, are not considered harmful by the NIDDK.

One study found that nuts and popcorn do not contribute positively or negatively to patients with diverticulosis or diverticular complications.

Complications

Complicated diverticulosis requires treatment of the complication. These complications are often grouped under a single diagnosis of diverticulitis and require skilled medical care of the infection, bleeding and perforation which may include intensive antibiotic treatment, intravenous fluids, and surgery. Complications are more common in patients who are taking NSAIDs or aspirin. As diverticulosis occurs in an older population such complications are serious events.

Epidemiology

The prevalence of diverticulosis progressively increases with age. Approximately 50% of people over the age of 60 and 70% of people over the age of 80 have diverticulosis. This disease is common in the U.S., Britain, Australia, Canada, and is uncommon in Asia and Africa. Large-mouth diverticula are associated with scleroderma. Diverticular disease is more common in collagen disorders such as Ehlers–Danlos syndrome.

History

The modern emphasis on the value of fiber in the diet began with Thomas L. Cleave. A strong case was made by Neil Painter and Adam Smith that a deficiency of dietary fiber is the cause of diverticular disease. They argued that the colonic muscles needed to contract strongly in order to transmit and expel the small stool associated with a fiber deficient diet. The increased pressure within the segmented section of the bowel over years gave rise to herniation at the vulnerable point where blood vessels enter the colonic wall.

Society and culture

Economics

"The complications of diverticulosis cause considerable morbidity in the United States; health care expenditures for this disorder are estimated to be $2.5 billion per year."