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:
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.
may result in altered bowel habit, lower abdominal pain, tenesmus, flatulence, distension, fevers, ureteric irritation,
Aetiology
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)
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
antibiotic Mx of diverticulitis
mild diverticulitis suitable for outpatient Mx
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
moderate diverticulitis warranting admission and iv Rx
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
severe diverticulitis
as for moderate but increase iv ampicillin dose to 2g per dose
may need emergent surgery especially if there is peritonitis present
abscess on CT scan
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