see also:

• the patient with acute abdominal pain in the ED

• diverticula are herniations of the mucosa and submucosa or the entire wall thickness through the muscularis and in Western cultures, 95-95% involve the sigmoid colon, while in those living in Africa and Asia, prevalence is only 0.2% of the population and it mainly affects the right side!
• 25% of those with diverticula will develop symptoms such as bleeding or or florid diverticulitis
• adolescent cases are rare and generally associated with genetic disorders involving connective tissues in particular, such as:
  • Williams-Beuren syndrome (WBS)
  • Ehlers-Danlos syndrome
  • Marfan's syndrome
  • cf
• Meckel's diverticulum is a rare congenital form but can present in adults
• prevalence is increasing in the Western cultures and now are found in over 25% of patients undergoing colonoscopy, with prevalence increasing with age with prevalence being ~5% in those adults under 40 years, ~30% by age 60 years and 65% by age 85 years.
• thought to be caused by low-fiber diet which is the highest risk factor for diverticular disease. The resultant low-bulk stool leads to increased segmentation of the colon during propulsion, causing increased intraluminal pressure and formation of diverticula.
• affluent, mainly indoor societies in which passing flatus is regarded as being anti-social, may be an important contributor due to the gas pressures resulting from flatus retention and colonic contractions - perhaps it is better out than in!
• risk increases with steroids and aging presumably due in part to impaired collagen maintenance.
• complications of diverticular disease include:
  • lower GIT bleeding:
    • 15% of those with diverticular disease will develop lower GIT bleeding - of these, 1/3rd will develop massive bleeding.
    • usually sudden onset of painless, bright red or wine colored stools and is often massive but usually stops spontaneously
  • perforation:
    • initial presentation may be as perforation and peritonitis
    • mortality following free perforation and generalised peritonitis exceeds 20%
  • diverticulitis +/- abscess formation +/- perforation +/- fistula formation
    • may result in altered bowel habit, lower abdominal pain, tenesmus, flatulence, distension, fevers, ureteric irritation,

• genetics
  • highly heritable with 150 genetic factors linked and contributes 40% of the risk of getting diverticulitis
  • these genes were highly correlated with genes for other digestive diseases, for example, irritable bowel syndrome ¹⁾
  • early onset and severe diverticulitis have been linked to LAMB4 and TNFSF15 mutations, which encode for laminin proteins and the tumor necrosis factor family, respectively - TNFSF15 mutation has been implicated in the development of surgical diverticulitis
  • ARHGAP15, FAM155A, and COLQ as single nucleotide polymorphisms associated with diverticulitis - the mutations affect 99 identified genes, with functions ranging from regulation of neutrophils, calcium transporters for the interstitial cells of Cajal, and components of the elastin protein
• low fibre diet
  • changes in diet may have an effect in the short term as the diet over the past 1-4 years seems to have more influence than longer term diet patterns
  • the following appear to REDUCE risk:
    • top quintile of dietary fiber consumption in the Nurses’ Health Study ²⁾
    • consumption of whole fruits (particularly apple, pear, and prune) and cereal fibers but note that vegetable intake does not appear to reduce risk significantly ³⁾
  • the following appear to INCREASE risk:
    • unprocessed red meat when compared to processed red meat, and that the risk plateaued after 6 servings of red meat a week ⁴⁾
    • diet-related inflammatory serum markers (C-reactive protein, interleukin-6, and tumor necrosis factor)
• low water intake
• advancing age
  • diverticula are present on a third of people aged 50-59yrs increasing to 71% for those aged over 80yrs
• use of non-steroidal anti-inflammatory drugs (NSAIDs)
  • appeared to give a higher risk in the Health Professionals Follow-Up Study ⁵⁾

• suspect in the older adult patient (particularly those with known diverticular disease) with LIF pain (LIF much more common than RIF) with no evidence of acute pyelonephritis, renal colic, abdominal aortic aneurysm (AAA) or gynaecologic cause
• initial assessment as per the patient with acute abdominal pain in the ED
• if rectal bleeding is the main presentation, then Mx as per lower GIT bleeding
• nil orally or minimal ice chips to rest gut
• iv fluids
• bloods for FBE, U&E, consider CRP (and LFT's and lipase if R abdominal pain, consider blood cultures if temp > 38.5degC)
• urinalysis
• iv analgesia
• consider anti-emetics if no evidence of bowel obstruction (see large bowel obstruction)
• strict fluid balance chart
• consider NGT if frequent vomiting
• consider IDC if clinical dehydration, or impaired renal function
• ECG if over 50 years age or risk of IHD
• plain AXR is unlikely to be helpful unless one suspects other diagnoses such as bowel obstruction or sigmoid volvulus
• contact surg team to decide on further Mx and possible CT abdomen
  • patients with known diverticular disease and mild symptoms may be considered for discharge on broad spectrum antibiotics without imaging
  • pelvic USS may be preferred over CT scan for women of child bearing age
  • CT abdomen with iv and oral contrast is now the gold standard for non-invasive diagnosis of diverticulitis
    • the two most common CT findings in uncomplicated diverticulitis are:
      • colonic wall thickening (wall thickness > 3 mm on the short axis of the lumen)
      • pericolic fat stranding
    • an identifiable inflamed diverticulum may also be visible
    • CT may fail to demonstrate early, mild cases of diverticulitis.
    • CT findings in complicated diverticulitis may include:
      • the presence of an abscess (defined as a fluid-containing mass with or without air and an enhancing wall)
      • contained or free extraluminal air bubbles or pockets
    • CT with rectal contrast is usually required to visualise fistulae, however, this is rarely performed

• eligible patients for outpatient Mx with close follow up:
  • stable patients with either:
    • uncomplicated diverticulitis (no abscess or peritonitis)
    • mild complicated diverticulitis (defined as abscess <4 cm or pneumoperitoneum <2 cm)
  • exclusions:
    • significant comorbidities
    • immunosuppression
• outpatient Mx:
  • no evidence to support dietary restrictions to reducing dietary fibre in acute flares for these patients
  • no evidence to support benefit of probiotics in these patients
  • recent studies suggest that antibiotic Rx may not confer significant benefit to this group of patients, nevertheless, current practice generally remains with antibiotics
  • augmentin duo forte i bd for 5-7 days
  • if penicillin HS, then cephalexin 500mg qid plus metronidazole 400mg bd for 5-7 days

• iv amoxicillin with clavulonic acid is usual preference if available
  • covers Enterococcus whereas ceftriaxone doesn't and doesn't have dosing complexities and ototoxicity of gentamicin
• alternatively, iv ampicillin 1g 6h PLUS iv metronidazole 500mg 12h PLUS iv gentamicin 4-6mg/kg/day adjusted to age, creatinine clearance and gentamicin levels
• or if penicillin HS, iv ceftriaxone + iv metronidazole
  • if HS or C/I then contact infectious diseases team to decide on alternative Rx
  • continue iv for 5-7 days then change to oral regime once clinical condition is improving and tolerating oral fluids for at least 24 hours

• as for moderate but increase iv ampicillin dose to 2g per dose
• may need emergent surgery especially if there is peritonitis present

• surg team to consider interventional radiology to drain it, or resort to bowel resection
• if less than 4cm, patient is well, not immunosuppressed and no major co-mordidities, it may not need to be drained