Diverticulitis

Diverticulitis is a common disease of the bowel, in particular the large intestine. Diverticulitis develops from diverticulosis, which involves the formation of pouches (diverticula) on the outside of the colon. Diverticulitis results if one of these diverticulum becomes inflamed. In complicated diverticulitis, bacteria may subsequently infect the outside of the colon if an inflamed diverticulum bursts open. If the infection spreads to the lining of the abdominal cavity, (peritoneum), this can cause a potentially fatal peritonitis. Sometimes inflamed diverticula can cause narrowing of the bowel, leading to an obstruction. Also, the affected part of the colon could adhere to the bladder or other organ in the pelvic area, causing a fistula, or abnormal communication between the colon and an adjacent organ. Diverticulitis most often affects middle-aged and elderly persons, though it can strike younger patients as well.

Incidence

In Western countries, diverticular disease most commonly involves the sigmoid colon (95% of patients). The prevalence of diverticular disease has increased from an estimated 10% in the 1920s to between 35 and 50% by the late 1960s. 65% of those currently 85 years of age and older can be expected to have some form of diverticular disease of the colon. Less than 5% of those aged 40 years and younger may also be affected by diverticular disease.

Left-sided diverticular disease (involving the sigmoid colon) is most common in the West, while right-sided diverticular disease is more prevalent in Asia and Africa.

Among patients with diverticulosis, 10-25% patients will go on to develop diverticulitis within their lifetimes.

Causes

The development of colonic diverticulum is thought to be a result of raised intraluminal colonic pressures. The sigmoid colon has the smallest diameter of any portion of the colon, and therefore the portion which would be expected to have the highest intraluminal pressure according to the laws of Laplace. The postulate that low dietary fiber, particularly non-soluble fiber (also known in older parlance as "roughage") predisposes individuals to diverticular disease is supported within the medical literature.

It is thought that mechanical blockage of a diverticulum, possibly by a piece of feces, leads to infection of the diverticulum.

Presentation

Patients often present with the classic triad of left lower quadrant pain, fever, and leukocytosis (an elevation of the white cell count in blood tests). Patients may also complain of nausea or diarrhea; others may be constipated.

Less commonly, an individual with diverticulitis may present with right-sided abdominal pain. This may be due to the less prevalent right-sided diverticula or a very redundant sigmoid colon.

Diagnosis

The differential diagnosis includes colon cancer, inflammatory bowel disease, ischemic colitis, and irritable bowel syndrome, as well as a number of urological and gynecological processes. Some patients report bleeding from the rectum.

In today's world of modern medicine, patients with the above symptoms are commonly studied with a computed tomography, or CT scan. The CT scan is very sensitive (98%) in diagnosing diverticulitis. It may also identify patients with more complicated diverticulitis, such as those with an associated abscess. CT also allows for radiologically guided drainage of associated abscesses, possibly sparing a patient from immediate surgical intervention.

Other studies, such as barium enema and colonoscopy are contraindicated in the acute phase of diverticulitis due to the risk of perforation.

Treatment

An initial episode of acute diverticulitis is usually treated with conservative medical management, including bowel rest (ie, nothing by mouth), IV fluid resuscitation, and broad-spectrum antibiotics which cover anaerobic bacteria and gram-negative rods. However, recurring acute attacks or complications, such as peritonitis, abscess, or fistula may require surgery, either immediately or on an elective basis.

Upon discharge patients are placed on a high-fiber diet. There is some evidence this lowers the recurrence rate.

Complications

• obstruction
• peritonitis
• abscess
• fistula
• bleeding
• strictures