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Clin Evid (Online). 2007; 2007: 0405.
Published online Aug 15, 2007.
PMCID: PMC2943810
Colonic diverticular disease
Mr David Humes, Research Fellow General Surgery,# Mr John Simpson, Lecturer in Surgery,# and Professor Robin C Spiller, Professor of Gastroenterology#
Mr David Humes, Department of Surgery, University of Nottingham, Nottingham, UK;
#Contributed equally.
JS, DH and RS declare that they have no competing interests.
Introduction
Diverticula (mucosal outpouching through the wall of the colon) affect over 5% of adults aged 40 years and older, but only 10-25% of affected people will develop symptoms such as lower abdominal pain. Recurrent symptoms are common, and 5% of people with diverticula eventually develop complications such as perforation, obstruction, haemorrhage, fistulae, or abscesses.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of: treatments for uncomplicated diverticular disease; treatments to prevent complications; and treatments for acute diverticulitis? We searched: Medline, Embase, The Cochrane Library and other important databases up to July 2006 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
Results
We found 13 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
Conclusions
In this systematic review we present information relating to the effectiveness and safety of the following interventions: antispasmodics, bran, elective surgery, increasing fibre intake, ispaghula husk, lactulose, medical treatment, mesalazine, methylcellulose, rifaximin, surgery.
Diverticula (mucosal outpouching through the wall of the colon) affect over 5% of adults aged 40 years and older, but only 10-25% of affected people will develop symptoms such as lower abdominal pain.
  • Recurrent symptoms are common, and 5% of people with diverticula eventually develop complications such as perforation, obstruction, haemorrhage, fistulae, or abscesses.
  • Use of non-steroidal anti-inflammatory drugs, corticosteroids, and opiate analgesics have been associated with an increased risk of perforation of diverticula, while calcium antagonists may protect against these complications.
Dietary fibre supplementation, and laxatives such as methylcellulose and lactulose are widely used to treat uncomplicated diverticular disease, but we don't know whether they reduce symptoms or prevent complications.
  • Antibiotics (rifaximin) plus dietary fibre supplementation may improve symptoms more than fibre alone, but increase the risk of adverse effects.
  • We don't know whether mesalazine is also beneficial at improving symptoms in uncomplicated diverticular disease, or at reducing complications after acute diverticulitis, as no good-quality studies have been found.
  • We don't know whether elective open or laparoscopic colonic resection improve symptoms in people with uncomplicated diverticular disease.
Acute diverticulosis is often treated with intravenous fluids, limiting oral intake, and broad spectrum antibiotic use. However, we don't know whether such medical treatment improves symptoms and cure rates in people with acute diverticulitis.
Surgery is usually performed for people with peritonitis caused by perforated acute diverticulitis, but we don't know whether it improves outcomes compared with no surgery, or if any one surgical technique is better at preventing complications.
Definition
Colonic diverticula are mucosal outpouchings through the large bowel wall. They are often accompanied by structural changes (elastosis of the taenia coli, muscular thickening, and mucosal folding). They are usually multiple, and occur most frequently in the sigmoid colon. The majority of people with colonic diverticula are asymptomatic, with little to find on clinical examination, while 20% develop symptoms at some point.[1] If diverticula are associated with symptoms, then this is termed diverticular disease. If asymptomatic, then the condition is known as diverticulosis. People who go on to develop complications associated with diverticula (inflammation, perforation, fistulae, abscess formation, obstruction, or haemorrhage) are referred to as having complicated diverticular disease. People with uncomplicated diverticular disease may report abdominal pain (principally colicky left iliac fossa pain), bloating, and altered bowel habit, and may have mild left iliac fossa tenderness on examination. Acute diverticulitis occurs when a diverticulum becomes acutely inflamed. People with acute diverticulitis typically present with severe left iliac fossa pain associated with fever, malaise, and altered bowel habit with left iliac fossa tenderness, associated with general signs of infection, such as fever and tachycardia.
Incidence/ Prevalence
In the UK the incidence of diverticulosis increases with age; about 5% of people are affected in their fifth decade of life, and about 50% by their ninth decade.[2] Diverticulosis is common in resource-rich countries, although there is a lower prevalence of diverticulosis in Western vegetarians consuming a diet high in fibre.[3] Diverticulosis is almost unknown in rural Africa and Asia.[4]
Aetiology/ Risk factors
There is an association between low-fibre diets and diverticulosis of the colon.[4] Prospective observational studies have found that both physical activity and a high-fibre diet are associated with a lower risk of developing diverticular disease.[5] [6] Case control studies have found an association between perforated diverticular disease and non-steroidal anti-inflammatory drugs, corticosteroids, and opiate analgesics, and have found that calcium antagonists have a protective effect.[7] [8] [9] [10] People in Japan, Singapore, and Thailand develop diverticula that affect mainly the right side of the colon.[11]
Prognosis
Inflammation will develop in 10-25% of people with diverticula at some point.[2] It is unclear why some people develop symptoms and some do not. Even after successful medical treatment of acute diverticulitis, almost two thirds of people suffer recurrent pain in the lower abdomen.[12] Recurrent diverticulitis is observed in 7-42% of people with diverticular disease, and after recovery from the initial attack the calculated yearly risk of suffering a further episode is 3%.[13] About 50% of recurrences occur within 1 year of the initial episode, and 90% occur within 5 years.[14] Complications of diverticular disease (perforation, obstruction, haemorrhage, and fistula formation) are each seen in about 5% of people with colonic diverticula when followed up for 10-30 years.[15] In the UK, the incidence of perforation is four cases per 100,000 people a year, leading to approximately 2000 cases annually.[16] Intra-abdominal abscess formation is also a recognised complication.
Aims of intervention
To reduce mortality, symptoms, and complications, with minimal adverse effects.
Outcomes
Subjective gastrointestinal symptoms assessed by the use of questionnaires; admission and readmission rates as a result of diverticular disease and its complications; and mortality. For the question about the effect of treatments for preventing recurrence and complications of diverticular disease, the primary outcomes of interest are as follows: incidence of diverticulitis, haemorrhage, perforation, abscess, fistula formation, and mortality from these complications. Stool weight and transit time are surrogate outcomes.
Methods
BMJ Clinical Evidence search and appraisal March 2007. The following databases were used to identify studies for this systematic review: Medline 1986 to March 2007, Embase 1986 to March 2007, and The Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Clinical Trials 2007, Issue 1. Additional searches were carried out using these websites: NHS Centre for Reviews and Dissemination (CRD) — for Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment (HTA), Turning Research into Practice (TRIP), and National Institute for Health and Clinical Excellence (NICE). We also searched for retractions of studies included in the Review. Abstracts of the studies retrieved from the initial search were assessed by an information specialist. The authors also performed their own search of Medline in July 2006. Selected studies were then sent to the author for additional assessment, using pre-determined criteria to identify relevant studies.Study design criteria for inclusion in this review were: published systematic reviews and RCTs in any language, at least single blinded, and containing more than 40 individuals of whom more than 80% were followed up. There was no minimum length of follow-up required to include studies. We excluded all studies described as "open", "open label", or not blinded unless blinding was impossible. We also did a search for cohort studies on specific harms of interventions. In addition we use a regular surveillance protocol to capture harms alerts from organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA), which are added to the reviews as required. We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table ).
Table
Table
GRADE evaluation of interventions for colonic diverticular disease
Glossary
Acute diverticulitis This condition occurs when a diverticulum becomes acutely inflamed. There may be general symptoms and signs of infection (including fever and rapid heart rate) with or without local symptoms and signs (pain and localised tenderness, usually in the lower left abdomen, sometimes with a mass that can be felt on abdominal or rectal examination).
Acute sigmoid colonic resection Immediate resection of the sigmoid colon, involving end colostomy of the proximal bowel and creating a mucus fistula with the distal bowel or oversewing the rectal stump.
Defunctioning colostomy Stoma created to divert faecal flow, such that faeces no longer flow through the anus.
Diverticular disease This term is used to describe diverticula associated with any symptoms. Symptoms commonly include abdominal pain and alteration in bowel habit. Diverticular disease may be complicated by abscess formation, fistulae, perforation, obstruction, or haemorrhage.
Low-quality evidenceFurther research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Moderate-quality evidenceFurther research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Rifaximin A rifamycin antibacterial drug with antimicrobial actions similar to those of rifampicin. It is marketed predominantly in Italy.
Very low-quality evidenceAny estimate of effect is very uncertain.

Notes
Disclaimer
The information contained in this publication is intended for medical professionals. Categories presented in Clinical Evidence indicate a judgement about the strength of the evidence available to our contributors prior to publication and the relevant importance of benefit and harms. We rely on our contributors to confirm the accuracy of the information presented and to adhere to describe accepted practices. Readers should be aware that professionals in the field may have different opinions. Because of this and regular advances in medical research we strongly recommend that readers' independently verify specified treatments and drugs including manufacturers' guidance. Also, the categories do not indicate whether a particular treatment is generally appropriate or whether it is suitable for a particular individual. Ultimately it is the readers' responsibility to make their own professional judgements, so to appropriately advise and treat their patients.To the fullest extent permitted by law, BMJ Publishing Group Limited and its editors are not responsible for any losses, injury or damage caused to any person or property (including under contract, by negligence, products liability or otherwise) whether they be direct or indirect, special, incidental or consequential, resulting from the application of the information in this publication.
Contributor Information
Mr David Humes, Department of Surgery, University of Nottingham, Nottingham, UK.
Mr John Simpson, Department of General Surgery, University Hospital Nottingham, Nottingham, UK.
Professor Robin C Spiller, Division of Gastroenterology, University Hospital Nottingham, Nottingham, UK.
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3. Gear JS, Ware A, Fursdon P, et al. Symptomless diverticular disease and intake of dietary fibre. Lancet 1979;1:511–514. [PubMed]
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5. Aldoori WH, Giovannucci EL, Rimm EB, et al. Prospective study of physical activity and the risk of symptomatic diverticular disease in men. Gut1995;36:276–282. [PMC free article] [PubMed]
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20. Papi C, Ciaco A, Koch M, et al. Efficacy of rifaximin in the treatment of symptomatic diverticular disease of the colon. A multicentre double-blind placebo-controlled trial. Aliment Pharmacol Ther 1995;9:33–39. [PubMed]
21. Latella G, Pimpo MT, Sottili S, et al. Rifaximin improves symptoms of acquired uncomplicated diverticular disease of the colon. Int J Colorectal Dis2003;18:55–62. [PubMed]
22. Di Mario F, Aragona G, Leandro G, et al. Efficacy of mesalazine in the treatment of symptomatic diverticular disease. Dig Dis Sci2005;50:581–586. [PubMed]
23. Trespi E, Colla C, Panizza P, et al. Therapeutic and prophylactic role of mesalazine (5-ASA) in symptomatic diverticular disease of the colon. 4-year follow-up results. Minerva Gastroenterol Dietol1999;45:245–252. [PubMed]
24. Kellum JM, Sugerman HJ, Coppa GF, et al. Randomized, prospective comparison of cefoxitin and gentamicin–clindamycin in the treatment of acute colonic diverticulitis. Clin Ther1992;14:376–384. [PubMed]
25. Larson DM, Masters SS, Spiro HM. Medical and surgical therapy in diverticular disease: a comparative study. Gastroenterology1976;71:734–737. [PubMed]
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29. Zeitoun G, Laurent A, Rouffet F, et al. Multicentre, randomized clinical trial of primary versus secondary sigmoid resection in generalized peritonitis complicating sigmoid diverticulitis. Br J Surg2000;87:1366–1374. [PubMed]

Bran and ispaghula husk
Summary
SYMPTOM RELIEF Compared with placebo: Bran and ispaghula husk may be no more effective than placebo at 16 weeks at relieving symptoms of uncomplicated diverticular disease ( very low-quality evidence ).
Benefits
Bran and ispaghula husk versus placebo:
We found no systematic review, but found one crossover RCT comparing fibre supplements versus placebo.[17] The crossover RCT (76 people with uncomplicated diverticular disease, no other gastrointestinal disorders, and no prior abdominal operations) compared three treatments: bran crispbread (6.99 g/day fibre), ispaghula husk drink (a bulk-forming laxative; 9.04 g/day fibre), and placebo (2.34 g/day fibre). It found no significant difference among treatments for pain score (score range: 0 = least severe, 100 = most severe), lower bowel symptom score (combination of the pain score and sensation of incomplete emptying, straining, stool consistency, flatus, and aperients taken; score range: 0 = least severe, 110 = most severe), or general symptom score (including nausea, vomiting, dyspepsia, belching, and abdominal distension; score range: 0 = least severe, 55 = most severe; see comment below) after 16 weeks (pain scores after treatment: 15.2 with bran v 19.5 with ispaghula husk v 17.5 with placebo; P value not reported; lower bowel symptom scores after treatment: 39.7 with bran v 41.3 with ispaghula husk v 45.0 with placebo; P value not reported; general symptom scores after treatment: 6.7 with bran v 8.1 with ispaghula husk v 7.6 with placebo; P value not reported). The RCT found that both active treatments significantly reduced straining at stool, increased wet stool weight and stool frequency, and significantly softened the stools after 16 weeks compared with placebo (straining: bran v placebo, P less than 0.01; ispaghula husk v placebo, P less than 0.001; wet stool weight: both active treatments v placebo, P less than 0.001; stool frequency: both active treatments v placebo, P less than 0.001; stool softening: both active treatments v placebo, P less than 0.001; CI not reported for any comparison). It was not clear whether these results were obtained before or after crossover.
Harms
No clinically important adverse effects were reported in the RCT.[17]
Comment
In the RCT, 18/76 (24%) people withdrew from the trial, and analysis of data was not by intention to treat.[17] The RCT did not specify the exact number of people receiving each treatment, precluding calculations of relative risk and confidence interval. People in the RCT had been investigated to exclude coexisting abdominal pathology, but the extent of the investigations was not stated.
Clinical guide:
Traditionally, the principal treatment of uncomplicated diverticular disease has been the use of dietary fibre supplementation and laxatives. There is little evidence to support their use, but some people report an improvement in symptoms.
Substantive changes
No new evidence

Methylcellulose
Summary
SYMPTOM RELIEF Compared with placebo: Methylcellulose may be no more effective at three months at reducing mean symptom scores in people with uncomplicated diverticular disease compared with placebo ( low-quality evidence ).
Benefits
Methylcellulose versus placebo:
We found no systematic review, but found one RCT (30 people with symptomatic diverticular disease and no other gastrointestinal disease), which compared methylcellulose (500 mg twice daily) versus placebo.[18] It found no significant difference between treatments in mean symptom score at 3 months (see comment below; mean symptom score: 13.0 with methylcellulose v 16.7 with placebo; difference in means: –3.7, 95% CI –8.9 to +1.5).
Harms
The RCT gave no information on adverse effects.[18]
Comment
The score used to assess symptoms and signs was not described clearly, but it included barium enema results.[18] The range of the score was 0–50, where 0 meant least severe symptoms and 50 meant most severe. The RCT was small and of short duration, and both the methylcellulose and placebo treatments were associated with an improvement in symptom scores. Diverticular disease was confirmed by barium enema, but the extent of other investigations to exclude comorbidity was not reported.
Clinical guide:
Traditionally, the principal treatment of uncomplicated diverticular disease has been the use of dietary fibre supplementation and laxatives. There is little evidence to support their use but some people report an improvement in symptoms.
Substantive changes
No new evidence

Summary
SYMPTOM RELIEF Compared with a high-fibre diet: Lactulose may be no more effective at 12 weeks than a high-fibre diet at relieving symptoms of uncomplicated diverticular disease ( very low-quality evidence ).
Benefits
We found no systematic review.
Lactulose versus placebo:
We found no RCTs.
Lactulose versus high fibre diet:
We found one RCT (43 people with diverticular disease and no other abdominal pathology) comparing lactulose (15 mL twice daily) versus a high-fibre diet (30–40 g/day fibre).[19] It found no significant difference in the proportion of people who reported their symptoms much improved after 12 weeks (see comment below; 7/20 [35%] with lactulose v 9/21 [43%] with high fibre diet; RR 0.80, 95% CI 0.34 to 1.77).
Harms
Lactulose versus high fibre diet:
The RCT found a non-significant increase in the risk of new symptoms with a high-fibre diet compared with lactulose (12/21 [57%] with high fibre diet v 9/20 [45%] with lactulose; RR 1.30, 95% CI 0.70 to 2.34).[19] The symptoms were described as minor, but no further details were provided. The RCT found that 2/20 (10%) people taking lactulose withdrew from the trial because of symptoms, one with abdominal pain and one with nausea.
Comment
Lactulose versus high fibre diet:
Although “much improved” was used as an outcome by the RCT, this term was not defined clearly.[19] People were investigated to exclude coexisting abdominal pathology, but the extent of the investigations was not reported.
Clinical guide:
Traditionally, the principal treatment of uncomplicated diverticular disease has been the use of dietary fibre supplementation and laxatives. There is little evidence to support their use, but some people report an improvement in symptoms.
Substantive changes
No new evidence

Antibiotics (rifaximin)
Summary
SYMPTOM RELIEF Compared with dietary fibre supplementation alone: Rifaximin plus a dietary fibre supplement (glucomannan) may be more effective at 12 months at relieving symptoms of uncomplicated diverticular disease compared with dietary fibre supplementation alone ( low quality evidence ).
Benefits
Rifaximin versus placebo:
We found no RCTs.
Rifaximin plus dietary fibre supplementation versus dietary supplementation alone:
We found no systematic review, but found two RCTs.[20] [21] The first RCT (168 people with uncomplicated diverticular disease) compared dietary fibre supplementation (glucomannan 2 g/day) plus oral rifaximin (400 mg twice daily) versus dietary fibre supplementation (glucomannan 2 g/day) plus placebo.[20] Both treatments were given for 7 days each month for 1 year (see comment below). The RCT found that dietary fibre supplementation plus rifaximin significantly increased the proportion of people with no symptoms or only mild symptoms after 12 months of treatment compared with dietary fibre supplementation alone (69% with rifaximin v 39% with placebo, P = 0.001; results presented graphically; absolute numbers not provided). The RCT found no significant difference between treatments in the severity of diarrhoea, tenesmus, or upper abdominal pain (absolute data and significance testing not reported). The second open RCT (968 people with diverticular disease) also compared dietary fibre supplementation (glucomannan 4 g/day) plus oral rifaximin (400 mg twice daily for 7 days every month) versus dietary fibre supplementation alone (glucomannan 4 g/day).[21] The RCT found that, at 12 months, dietary fibre supplementation plus rifaximin improved global symptom score significantly more than dietary fibre supplementation alone (global symptom score assessed on six clinical variables: upper abdominal pain/discomfort, lower abdominal pain/discomfort, bloating, tenesmus, diarrhoea, and abdominal tenderness; each variable was rated from 0 [no symptoms] to 3 [severe] and summed for a total maximum score of 18; score changed from 6.5 at baseline to 1.0 with dietary fibre supplementation plus rifaximin v from 6.3 at baseline to 2.0 with dietary fibre supplementation alone; P = 0.003).
Rifaximin versus mesalazine:
See benefits of mesalazine.
Harms
Rifaximin plus dietary fibre supplementation versus dietary supplementation alone:
The first RCT gave no information on adverse effects.[20] In the second open RCT, 10 people (1.7%) taking rifaximin plus glucomannan and five (1.3%) taking glucomannan alone experienced adverse effects (nausea, headache, and weakness).[21]
Rifaximin versus mesalazine:
See harms of mesalazine.
Comment
Rifaximin plus dietary fibre supplementation versus dietary supplementation alone:
One RCT reported that 17/168 (10%) people did not complete the trial, although analysis was not by intention to treat.[20] For each treatment group, 2/84 (2%) people were withdrawn because of acute diverticulitis.
Rifaximin versus mesalazine:
See comments for mesalazine.
Clinical guide:
The evidence suggests that broad spectrum antibiotics may be beneficial as a treatment for uncomplicated diverticular disease. However, before making any firm recommendations, a placebo-controlled, double-blind RCT investigating their use should be performed.
Substantive changes
No new evidence

Elective surgery
Summary
We found no direct information about elective open or laparoscopic colonic resection in the treatment of people with uncomplicated diverticular disease.
Benefits
We found no systematic review or RCTs of elective open or laparoscopic colonic resection in people with uncomplicated diverticular disease.
Harms
We found no data on adverse effects of elective surgery in people with diverticular disease.
Comment
None.
Substantive changes
No new evidence

Mesalazine
Summary
SYMPTOM RELIEF Compared with rifaximin: We don't know whether mesalazine may be more effective than rifaximin at 3 months at reducing symptom scores in people with uncomplicated diverticular disease ( very low-quality evidence ).
Benefits
We found one RCT, which compared rifaximin 200 mg twice daily, rifaximin 400 mg twice daily, mesalazine 400 mg twice daily, and mesalazine 800 mg twice daily, for 10 days per month for 3 months.[22] The RCT found that, at 3 months, either dose of mesalazine reduced physician-rated global symptom score significantly more than rifaximin 200 mg twice daily (170 people with symptomatic colonic diverticular disease; global symptom score range: 0 = no symptoms to 33 = most severe symptoms; mean score reduction from baseline: 4.3 with mesalazine 400 mg twice daily v 3.9 with mesalazine 800 mg twice daily v 0.8 with rifaximin 200 mg twice daily v 3.9 with rifaximin 400 mg twice daily; P less than 0.05 for either dose mesalazine v rifaximin 200 mg twice daily). There was no significant difference between either dose of mesalazine and rifaximin 400 mg twice daily in global symptom score (difference reported as not significant; P value not reported). The second RCT was open label, and people were randomly assigned into two treatment groups of mesalazine 1.6 g/d or 1.6 g/d for 10 days a month.
Harms
The RCT reported no withdrawals.[22] It did not provide information on adverse effects.
Comment
The RCT had several methodological flaws:[22] the study was open label; no details were given about the randomisation protocol; a non-validated physician-rated global symptom scale was used as an outcome measure; no power calculation was performed; and there was no placebo arm. It should be noted that mesalazine was given intermittently in this RCT. It is unclear why this dosing strategy was adopted, because mesalazine is given continuously without serious adverse effects when used to prevent recurrence of colitis.
Substantive changes
No new evidence

Antispasmodics
Summary
We found no direct results about antispasmodics in the treatment of people with uncomplicated colonic divertucular disease.
Benefits
We found no systematic reviews or RCTs of sufficient quality.
Harms
We found no systematic reviews or RCTs of sufficient quailty.
Comment
Well-designed, appropriately powered RCTs are needed to assess the role of antispasmodics for uncomplicated colonic divericular disease.
Substantive changes
New option added Antispasmodics for uncomplicated colonic diverticular disease .

Advice to increase fibre intake
Summary
We found no direct information about complication rates after advice to consume a high-fibre diet, or for dietary fibre supplementation in people with colonic diverticular disease.
Benefits
We found no systematic review or RCTs.
Harms
We found no RCTs.
Comment
Clinical guide:
Fibre is often used with the aim of preventing complications in people with diverticular disease because observational studies have found that the disease is less frequent in populations with high-fibre intake (see incidence/prevalence).
Substantive changes
No new evidence

Mesalazine
Summary
RECURRENCE OF SYMPTOMS Compared with no treatment: Mesalazine may be more effective at 4 years than no treatment at reducing recurrence of symptoms of diverticulitis in people previously treated for an episode of acute diverticulitis ( very low-quality evidence ).
Benefits
Mesalazine versus no treatment:
We found no systematic review, but we found one RCT.[23] The RCT (166 people previously treated for an episode of mild/moderate diverticulitis) compared 8 weeks of treatment with oral mesalazine (400 mg twice daily) versus no treatment.[23] People in both groups had received intramuscular sulbactam–ampicillin (1.5 g twice daily) and oral rifaximin (400 mg twice daily) for 7 days before randomisation. The RCT found that mesalazine reduced symptomatic recurrence of diverticulitis at 4 years compared with no treatment (12/81 [15%] with mesalazine v 39/85 [46%] with no treatment; RR 0.32, 95% CI 0.18 to 0.57; NNT 4, 95% CI 3 to 6). See comment below.
Harms
Mesalazine versus no treatment:
The RCT found that abdominal pain was more common with mesalazine than with no treatment (13/81 [16%] with mesalazine v 4/85 [5%] with no treatment; RR 3.40, 95% CI 1.16 to 10.00; NNH 8, 95% CI 4 to 70).[23]
Comment
Mesalazine versus no treatment:
The RCT provided insufficient information on several factors.[23] The recurrence of inflammation was diagnosed according to unspecified clinical and laboratory criteria. Methods for determining symptom scores, including the assessment and diagnosis of pain, were not reported. A total of 45 people did not complete the study, but there were similar withdrawal rates between groups (3 people died, 9 people had a severe complication of diverticular disease, and 33 were withdrawn because of “poor” adherence to treatment [poor adherence was not defined]).[23]
Clinical guide:
The use of mesalazine following an episode of acute diverticulitis has not found widespread application. The evidence regarding its use is poor and methodologically flawed. A placebo-controlled, double-blind RCT investigating its use should be performed.
Substantive changes
No new evidence

Medical treatment
Summary
CURE RATES Compared with each other: Intravenous cefoxitin is as effective as intravenous gentamicin plus intravenous clindamycin at increasing cure rates in people with acute diverticulitis ( moderate-quality evidence) . NOTE We found no direct information about whether medical treatment is better than no active treatment in people with acute diverticulitis. Observational studies in people with acute diverticulitis have found low mortality with medical treatment, but that recurrence rates may be high.
Benefits
We found no systematic review.
Medical treatment versus placebo:
We found no RCTs.
Medical treatments versus each other:
We found one RCT (51 people with a clinical diagnosis of acute diverticulitis who did not need immediate surgery), which compared intravenous cefoxitin (1–2 g every 6 hours) versus intravenous gentamicin (1.7 mg/kg loading dose followed by 1.0–1.4 mg/kg every 8 hours) plus intravenous clindamycin (total dose of 2400–2700 mg/day in 3 or 4 equal doses).[24] It found no significant difference in clinical cure rate (see comment below; 27/30 [90%] with cefoxitin v 18/21 [86%] with gentamicin plus clindamycin; RR 1.10, 95% CI 0.85 to 1.30).
Harms
Medical treatment versus placebo:
We found no RCTs.
Medical treatments versus each other:
In the RCT, toxicity (possibly antibiotic related) occurred with both treatments, although the proportion of people affected was not significantly different between treatments (2/30 [7%] with cefoxitin v 3/21 [14%] with gentamicin plus clindamycin; RR 0.47, 95% CI 0.09 to 2.56).[24]
Comment
Medical treatments versus each other:
Clinical cure was defined as: complete resolution of symptoms and signs associated with diverticulitis, plus discharge from hospital without recurrence for at least 6 weeks; or complete resolution of symptoms and signs, plus having had an elective surgical procedure with primary anastomosis in the absence of colostomy without septic complications.[24] We found many observational studies of medical treatment for acute diverticulitis, with variable follow-up periods (1–12 years), which consistently report low mortality (0–5%).[13] [25] [26] [27] These observational studies also reported that 7–42% of people treated medically suffer recurrent episodes of acute diverticulitis.
Clinical guide:
The treatment of acute diverticulitis by intravenous fluid replacement, limiting oral intake, and broad spectrum antibiotics is common practice, but is not supported by a strong evidence base. People with mild symptoms and no evidence of generalised sepsis can be managed at home with oral antibiotics. People with severe pain, or signs of compromise, should be admitted for analgesia, bowel rest, intravenous fluid replacement, and intravenous antibiotics.
Substantive changes
No new evidence

Summary
MORTALITY Acute sigmoid colonic resection compared with no acute resection: Mortality rates at 30 days may be the same with acute sigmoid colonic resection compared with no acute resection in people with acute diverticulitis ( low-quality evidence ). Primary sigmoid colonic resection compared with secondary sigmoid resection: Mortality rates are the same with primary sigmoid colonic resection compared with secondary sigmoid colonic resection in people with acute complicated diverticulitis ( moderate-quality evidence ). POST-OPERATIVE COMPLICATIONS Acute sigmoid colonic resection compared with no acute resection: Post-operative complications may be the same with acute sigmoid colonic resection compared with no acute resection in people with acute diverticulitis ( low-quality evidence ). Primary sigmoid colonic resection compared with secondary sigmoid resection: Primary sigmoid colonic resection is more effective at reducing post-operative peritonitis after the initial procedure, and the need for emergency re-operation, compared with secondary sigmoid resection in people with acute complicated diverticulitis, but is no more effective at reducing rates of wound or extra-abdominal complications ( moderate-quality evidence ). NOTE We found no direct information about whether surgery is better than no active treatment or medical treatment in people with acute diverticulitis. We found no clinically important results about open surgery compared with laparoscopic surgery.
Benefits
We found no systematic review.
Surgery versus placebo, no surgery, or medical treatment:
We found no RCTs.
Comparison of different types of open surgery:
We found two RCTs.[28] [29] Both were small, and may have lacked power to detect clinically important effects. The first RCT (62 people with diffuse peritonitis caused by perforated acute diverticulitis of the left colon; median age 72 years) compared acute sigmoid colonic resection versus no acute resection (acute transverse colostomy, suture, and omental covering of a visible perforation).[28] The RCT found no significant difference in mortality within 30 days between acute sigmoid colonic resection and no acute resection (mortality: 8/31 [26%] with acute resection v 6/31 [19%] with no acute resection; RR 1.30, 95% CI 0.52 to 3.39). However, subgroup analysis of people with purulent peritonitis (46 people) found that acute sigmoid colonic resection significantly increased postoperative mortality compared with no acute resection (6/25 [24%] with acute resection v 0/21 [0%] with no acute resection; ARI 24.0%, 95% CI 4.5% to 44.0%). Subgroup analysis of people with faecal peritonitis (16 people) found no significant difference between acute sigmoid colonic resection and no acute resection in postoperative mortality (2/6 [33%] with acute resection v 6/10 [60%] with no acute resection; RR 0.60, 95% CI 0.16 to 1.92; see comment below). This latter subgroup analysis probably lacked power to detect a clinically important difference. The second RCT (105 people with generalised peritonitis caused by sigmoid diverticulitis; mean age 66 years) compared primary versus secondary sigmoid colonic resection.[29] Primary resection involved surgical removal of the affected sigmoid colon plus either formation of an end colostomy, or formation of a primary colorectal anastomosis with or without a proximal defunctioning colostomy. Secondary resection involved initial closing of any visible bowel perforations plus the formation of a defunctioning colostomy. A second (definitive) procedure was then undertaken at a later date to perform a sigmoid colon resection plus a colorectal anastomosis with or without a defunctioning colostomy. The RCT found that primary sigmoid colonic resection significantly reduced rates of postoperative peritonitis after the initial procedure and significantly reduced rates of emergency reoperation compared with secondary sigmoid colonic resection (postoperative peritonitis: 1/55 [2%] with primary resection v 10/44 [23%] with secondary resection; RR 0.09, 95% CI 0.01 to 0.70; NNT 5, 95% CI 3 to 12; emergency reoperation: 2/55 [4%] with primary resection v 9/48 [19%] with secondary resection; RR 0.19, 95% CI 0.04 to 0.90; NNT 7, 95% CI 4 to 35). The RCT found no significant difference between treatments in mortality (13/55 [24%] with primary resection v 9/48 [19%] with secondary resection; RR 1.30, 95% CI 0.60 to 2.70; see comment below).
Open surgery versus laparoscopic surgery:
We found no RCTs.
Harms
Comparison of types of open surgery:
The first RCT found no significant difference in rates of cardiopulmonary complications, thromboembolism, mental confusion, or other complications including wound dehiscence, wound infection but no dehiscence, intraperitoneal abscess formation, ileus, colo-cutaneous fistula, and revision of colostomy, between acute resection and no acute resection (cardiopulmonary complications: 13/31 [42%] with acute resection v 14/31 [45%] with no acute resection; RR 0.90, 95% CI 0.53 to 1.63; thromboembolism: 3/31 [10%] with acute resection v 5/31 [16%] with no acute resection; RR 0.60, 95% CI 0.16 to 2.30; mental confusion: 4/31 [13%] with acute resection v 4/31 [13%] with no acute resection; RR 1.00, 95% CI 0.27 to 3.65).[28] The second RCT found no significant difference between treatments in rates of wound complications, extra-abdominal septic complications, or extra-abdominal non-septic complications (wound complications: 20/55 [36%] with primary resection v 23/48 [48%] with secondary resection; RR 0.80, 95% CI 0.48 to 1.20; extra-abdominal septic complications: 11/55 [20%] with primary resection v 12/48 [25%] with secondary resection; RR 0.80, 95% CI 0.39 to 1.65; extra-abdominal non-septic complications: 26/55 [47%] with primary resection v 21/48 [44%] with secondary resection; RR 1.08, 95% CI 0.71 to 1.65).[29]
Open surgery versus laparoscopic surgery:
We found no RCTs.
Comment
The first RCT was conducted in a single centre, and took 14 years to recruit 62 people.[28] The second RCT was conducted in 17 centres, and took 7 years to recruit 105 people.[29] Both studies were small, and might have lacked power to detect a significant difference between treatments. The high complication rates reported are not surprising in predominantly elderly people after a perforation of the large bowel. The wide spectrum of presentation and operative treatment options for acute complicated diverticulitis makes RCTs difficult to perform.
Clinical guide:
The wide spectrum of presentation and operative treatment options for complicated diverticulitis makes RCTs difficult to perform. In people with clinical features suggestive of colonic perforation, a period of resuscitation followed by expedient surgery should be undertaken. The aim of this surgery should be to decontaminate the peritoneal cavity and prevent any further contamination.
Substantive changes
No new evidence
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