Fallacies about Diverticulitis challenged by new research

Internists now know that patients who have a sibling with diverticulitis can have three times the risk for the disease, and a low-risk lifestyle decreases risk of incident diverticulitis by half. Nuts, seeds, and popcorn are now OK. Annually in the U.S., diverticulitis is responsible for 2.5 million office visits, 333,000 ED visits, 216,000 hospital admissions, and health care costs of $3.5 billion, Dr. Anne F Peery , Gastroenterologists at  University Of North Carolina, Chapel Hill,said. Incidence increases by age and differs by gender: Before age 50, the condition is more common in men, and after age 60, it is more common in women, she said.

Genetics contribute substantially to risk, Dr. Peery said. Research has shown that patients who have a sibling with diverticulitis can have three times the risk for the disease and that 50% of the susceptibility to diverticulitis comes from inherited factors.

Research has also shown that a low-risk lifestyle decreases risk of incident diverticulitis by 50%, she said. She described a low-risk lifestyle as one that includes a diet of less than 51 g of red meat and more than 23 g of dietary fiber per day, at least two hours of vigorous physical activity per week, a normal body mass index, and no history of smoking.

Nuts, seeds, and popcorns have long been considered risk factors for diverticulitis, since it was thought that they could get trapped in the diverticula and precipitate incidence, but their bad reputation is unearned, Dr. Peery said: “They are not risk factors.”

However, regular use of NSAIDs, defined as at least twice a day, is an important but little-known risk factor, doubling the risk, Dr. Peery said. “Aspirin also increases the risk, but not to the degree of NSAIDs.” Chronic use of corticosteroids is another risk factor. “We think it also increases the risk of complicated disease, and this probably can be extended to other immunosuppressants,” she said.

Patients with diverticulitis typically present with acute-onset pain in the lower left quadrant that is constant and worsens with movement, Dr. Peery said. “The triad of diverticulitis is left lower quadrant pain, fever, and a white count, but you should know that among patients with diverticulitis, 40% are afebrile, and 20% of patients with diverticulitis do not have a white count,” she said.

Dr. Peery stressed that every patient who presents with lower GI symptoms should get a digital rectal exam. “You want to rule out a stricture. You want to rule out a mass. With a stricture or a mass, the rectum begins to fill, the sigmoid colon begins to fill. These patients present not with anorectal symptoms but with abdominal pain.”

Patients with diverticulitis may be tender on digital rectal exam, because the rectum sits next to the sigmoid colon, Dr. Peery said. Also, she noted that if there is gross blood in the rectal vault, the patient is very unlikely to have diverticulitis.

Presumptive diagnosis of diverticulitis based on history and physical is right only 50% of time, Dr. Peery said, so there have been several attempts to create decision-making tools, but none have been entirely successful.

“It's hard to make a diagnosis of diverticulitis, which is why CT imaging is important,” Dr. Peery said.
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Abdominal CT should be done in patients with suspected diverticulitis if there is any concern about a possible complication, Dr. Peery said. She also noted that CT is useful for confirming a first episode of diverticulitis and for documenting recurrence. However, the test isn't perfect: A recent trial found that 1% of patients found to have acute uncomplicated diverticulitis on CT actually had colon cancer.

U.S. guidelines recommend colonoscopy eight weeks after a first diverticulitis episode to rule out this misdiagnosis, Dr. Peery said. However, she said, “If your patient has had a high-quality screening exam in the last two to three years, they don't need a repeat colonoscopy.”

Recurrent diverticulitis is common—five-year risk for recurrence and re-recurrence is 20% and 44%, respectively—but is not associated with increased risk of complications, Dr. Feery stressed. “We used to tell our patients, ‘Gosh, that next episode might be really, really bad. You might need emergency surgery,’” she said. “We were wrong. That's not true.” She noted, however, that persistent mild to moderate abdominal pain is common in patients with diverticulitis after the acute inflammation has resolved.

Historically, treatment for diverticulitis has consisted of a clear liquid and a course of antibiotics, Dr. Feery said. The liquid diet is given until symptoms begin to improve, at which point the patient can advance to a low-fiber diet, then finally to a balanced, healthy diet once their symptoms resolve.

Dr. Feery noted that there has been debate about the use of antibiotics in uncomplicated diverticulitis, with some researchers questioning whether the condition may be due to focal inflammation rather than focal infection. Two recent randomized controlled trials in Europe found no difference in time to recovery from acute symptoms in patients with CT-confirmed diverticulitis who received antibiotics versus those who did not.

“Based on these trials, several European countries now recommend that acute uncomplicated diverticulitis be managed conservatively without antibiotics,” Dr. Peery said.

U.S. guidelines, meanwhile, suggest that antibiotics be used selectively rather than routinely in patients with acute uncomplicated diverticulitis. This is a conditional recommendation based on low-quality evidence, Dr. Peery noted. The guidelines also recommend that antibiotics be given to patients with diverticulitis and complications, severe symptoms, or comorbid conditions, or in those who are immunocompromised. Physicians can consider withholding the drugs in patients with CT-proven uncomplicated diverticulitis who are stable, immunocompetent, adherent, and have good social support, Dr. Peery reported.

“But there are still big questions whether or not omitting antibiotics impacts the chronic sequelae,” she said. “So I personally will continue to treat my patients with diverticulitis [with antibiotics] until we have better evidence.”