New Guidelines on Acute Diverticulitis: How Will They Change Clinical Practice?

David A. Johnson, MD


January 21, 2016

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Diverticulitis: A Very Common Diagnosis

Hello. I'm Dr David Johnson, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia.

The paradigm of antibiotics for acute diverticulitis is something that we were all taught in medical school. However, this paradigm may be ready for a shift because of new guideline recommendations from the American Gastroenterological Association (AGA) Institute.[1,2] Let's just give you a little bit of background and then talk through the specific points of the recent guidelines.

Certainly, encountering diverticulosis is very common when we do colonoscopy, and there is about a 4% lifetime risk for diverticulitis in these patients.[3] The risk for diverticulitis is quite low, but approximately 15% of patients with diverticulitis will have complicated disease (eg, abscess, perforation, fistula, or some type of colonic obstruction).[4] With diverticulitis, there's also a relative risk for recurrence of 15%-30%.[5,6,7]

Diverticulitis is a very common diagnosis in the United States. The cost of its inpatient care is exponential, at an estimated $2 billion a year.[8] It's a very common outpatient and emergency department diagnosis as well. Those costs, though, are just attributable to the inpatient setting.

Antibiotics May Not Improve Outcomes in Diverticulitis

There are several recent studies that have prompted a re-evaluation of using antibiotics for acute diverticulitis. There were two prospective trials to support this paradigm shift.

One recently published trial included approximately 670 patients from Sweden and Iceland who were allocated on an inpatient basis to receive 7 days of antibiotics or intravenous fluids only.[9] The trial found no significant difference in the time to resolution of symptoms, complications, duration of hospital stay, or the risk for recurrence.

A second trial included approximately 530 patients from The Netherlands who had a first occurrence of imaging-confirmed acute uncomplicated diverticulitis.[10] Patients, now inpatients, were allocated to receive either 10 days of antibiotics or observation. Similarly, this trial found no significant difference in time to resolution of symptoms, complications, duration of hospital stay, or risk for recurrence.

These trials prompted a lot of concern; and, in Europe, there are four countries that have already changed their national guideline recommendations regarding the use of antibiotics. The Dutch, Danish, German, and Italian society consensus reports now say that antibiotics can be omitted in patients without risk factors who have uncomplicated disease, but these patients should be monitored closely. The recommendation is that you can hold off on antibiotics; but, nonetheless, these patients need closer monitoring.

The idea of withholding antibiotics is a growing drumbeat in the United States. We certainly have a compelling story because of the prevalence of Clostridium difficile diarrhea, as well as the antibiotic stewardship initiative, with the government looking for a national action plan to combat antibiotic resistance related to antibiotic exposure.

Antibiotics, Colonoscopy, and Resective Surgery

Let's look at the specifics of the recommendation from the AGA Institute.

The guidelines were scored using the GRADE recommendations, based on the strength of the recommendation as either strong or conditional. For a strong recommendation, most individuals should receive the recommended course of action. For a conditional recommendation, the clinician should look at different choices that will be appropriate for different individuals and on a more case-by-case basis.

The first recommendation relates to routinely using antibiotics in patients with uncomplicated diverticulitis and is based on two randomized trials, two systematic reviews, and a Cochrane review. An important consideration is that these were studies that were all done in inpatients, they had very close follow-up, and they had uncomplicated disease confirmed by CT scan. So, this recommendation would exclude those patients with severe infections, sepsis, immunosuppression, or other significant comorbidities or systemic features of disease (eg, high white blood cell count, fever, sepsis). These systemic features would obviously make a compelling story for antibiotics.

The second question relates to colonoscopy after an episode of diverticulitis, which is commonly done. The data support that it should be done, with a conditional recommendation but low quality of evidence. This is based on observational cohort studies looking at the incidence of colorectal cancer in patients following an episode of imaging-confirmed diverticulitis, with 15 cases per 1000 patients and 38 advanced adenomas per 1000 patients.[11] The absence of a mass lesion does not exclude abdominal concern, at least for colorectal cancer. So, it's still reasonable, at least from this recent guideline, to consider colonoscopy, obviously taking into account how recent was their last colonoscopy. The optimal time frame would be at least deferring it for 6-8 weeks after an acute episode to allow resolution of the tissue thinning.

The third question relates to whether there should be elective resection after an initial episode of uncomplicated diverticulitis. Here there is a conditional recommendation with very low quality of evidence. The likelihood of a patient developing a complication after elective sigmoid resection is about 10%.[2] The risk for future complications after a recurrent episode is about 20% in 5 years, and then the risk for future complications and emergency surgery is extremely low, less than 5%.[2] From a patient perspective, avoiding a recurrent episode would be enticing, but potential complications of the surgery are concerning. The guideline cites short-term complications, such as wound infection and anastomotic and cardiothoracic complications in particular; these increase as patients age and occur in approximately 10% of patients after an elective sigmoid resection.[2] The long-term complications in these resections are of even more concern, with up to 25% of patients with complications of abdominal distension, cramping, altered defecation, and fecal incontinence.[12,13] Routine sigmoid resection or resection of the area would not be recommended at present.

Fiber, Diet, Probiotics, and Concurrent Medication Use

How about the idea of fiber in patients with acute diverticulitis? Fiber really doesn't hurt, so it's not a bad thing, but there's really no strong evidence. There is one case-control study that suggested that there may be a benefit.[14] However, the tradeoff with bloating is the key issue. Despite very low quality evidence, it has a conditional recommendation in the guidelines.

Let's take it a step further about the standard question we get from our patients with diverticulitis. How about nuts and popcorn? Again, the guidelines provide a conditional recommendation with very low quality of evidence. These foods aren't really a problem in patients with a history of diverticulitis. However, the data are very limited. The studies that have suggested harm have very modest estimates of relative risk, and there's a high degree of uncertainty with these studies. We can tell patients that, according to the guidelines, it is okay to eat nuts and popcorn. Seeds might be the same thing because a lot of patients really get into this dietary exclusion, which is quite rigorous, based on recommendations from their primary care physicians.

The next area is the use of nonsteroidal anti-inflammatory drugs (NSAIDs). The first one they tackled was aspirin and whether it should be avoided in patients with acute diverticulitis. Their conditional recommendation, with low quality of evidence, is that aspirin should not be avoided, particularly if there is an indication for secondary prophylaxis in cardiovascular disease. There is minimal risk as it relates to diverticulitis recurrence. Nevertheless, they do suggest that other NSAIDs should be avoided, with a conditional recommendation. Although there is very low quality of evidence, observational studies indicate a moderately increased risk for occurrence of diverticulitis. That is something that I counsel my patients on routinely.

The guidelines also addressed rifaximin and mesalamine use and recommend against using these agents for prevention or the initial treatment of diverticulitis.

The one issue that I think warrants a little bit of discussion is the use of probiotics. The guidelines recommend against the routine use of probiotics after acute uncomplicated diverticulitis. This was given a conditional recommendation with very low quality of evidence. The caveat I would have is that there are data from a randomized controlled trial, which was very well done, looking at the use of mesalamine and Lactobacillus casei given 10 days of the month for a month (ie, 10 out of the 30 days) and then repeated and continued.[15] There was 0% recurrence in this trial with 120 patients with diverticulitis on this particular regimen. I've used that in my really refractory, relapsing nonsurgical candidate patients and have had some anecdotally good results. I wouldn't throw the probiotic and mesalamine out entirely; look at that as a potential option.


In summary, we now have a paradigm shift that maybe diverticulitis shouldn't be treated with antibiotics, recognizing that in some cases, it may be more of an inflammatory process and not an infection. It's safe to say that it is reasonable to withhold these antibiotics in patients with uncomplicated disease and closely follow them.

I think the recommendations on diet would really be welcomed news to our patients going forward because a lot of these patients become "dietary cripples," worried about what they can eat. This guideline reassures us, at least in the evidence suggesting that we can allow them to have a little more latitude in their diet.

No antibiotics? Boy, that's a long way from what we were talking about in the emergency department 34 years ago. But things change in science, and I hope that this provides you some insight the next time you face a patient with acute uncomplicated diverticulitis.

I'm Dr David Johnson. Thanks again for listening.


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