Diverticular Disease Flashcards

1
Q

What is diverticular disease?

A
  • common condition in which many diverticula develop in the large bowel
  • almost always in the sigmoid colon
  • incidence rises with increasing age
  • particularly common in western world, occurring in 50% of ppl 60+
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2
Q

What is a diverticulum?

A
  • plural: diverticula
  • a pouch of colonic mucosa that has herniated through the muscularis propria
  • and has come to lie in the subserosal (pericolic) fat outside the bowel wall
  • note the outer wall of diverticula is supported only by a thin layer of subserosal connective tissue
  • so diverticula are prone to perforation when they are obstructed and/or inflammed
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3
Q

What are the 2 factors important for diverticula formation?

A
  • areas of weakness in the colonic wall:
    • there are natural defects in the circular muscle layer where blood vessels pass through to supply the submucosa and mucosa
  • raised intraluminal pressure due to insufficient dietary fibre:
    • fibre binds salt and water in the colon resulting in bulky, moist faeces that are easily propelled through colon
    • movement of faeces from a low fibre diet along colon requires increased muscular effort which results in muscular hypertrophy and inc intraluminal pressure. As a consequence, diverticula are more likely to form
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4
Q

What is the most common site for diverticula formation and why?

A
  • sigmoid colon
  • has the smallest diameter of any portion of large bowel
  • therefore site where intraluminal pressure highest
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5
Q

What is the difference between diverticulosis and diverticulitis?

A
  • osis = diverticula are present but asymptomatic
  • itis = an acutely inflammed diverticulum, the most common presentaton
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6
Q

So how is acute diverticulitis initiated (pathophys)?

A
  • when faecal matter impacts and obstructs neck of diverticulum
  • this leads to trapping of bacteria
  • consequent bacterial replication in occluded lumen
  • -> infection and mucosal injury
  • local trauma (‘rubbing’) to mucosa by faecolith may also cause mucosal injury
  • mucosal injury initiates an acute inflammatory response, resulting in acute diverticulitis
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7
Q

What are the clinical features of acute diverticulitis?

A
  • abdominal pain (usually LIF)
  • malaise
  • fever
  • localised tenderness
  • no peritonisim
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8
Q

How does an abscess form from acute diverticulitis? What is an abscess?

A
  • an abscess is a localised collection of pus within a newly-formed cavity in the tissue
  • acute inflammatory response process may extend beyond diverticulum into surrounding subserosal tissue -> formation of a pericolic abscess
  • the cavity forms bc of breakdown and destruction of body’s tissue
  • pus consists of inflammatory cells (mainly neutrophils) admixed w/ cellular debris, fbirin and oedema fluid
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9
Q

What can the pericolic abscess lead to?

A
  • pericolic abscess may perforate into the abdominal cavity
  • resulting in bacerial peritonitis
  • alternatively, an inflamed diverticulum may perforate directly into the abdominal cavity, also resulting in faecal peritonitis
  • inflamed diverticula are particularly prone to perforate bc the wall of the diverticulum is supported only by a thin layer of subserosal tissue
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10
Q

Why might a fistula form from diverticulitis?

A
  • rarlely, as a consequence of inflammation
  • fistula is an abnormal connection between two epithelial surfaces
  • fistula may form between sigmoid colon and bladder
  • this presents clinically as faecaluria (passing faecal matter in urine)
  • fistulae may also form to the vagina
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11
Q

Why might a stricture form as a consequence of diverticular disease?

A

because of:

  • smooth muscle hypertrophy and hyperplasia due to low fibre diet
  • fibrosis around diverticula (repeated episodes of inflammation heal by fibrosis)

both of these factors lead to a reduction in the diameter of the lumen ie. a stricture - they present with clinical features of bowel obstruction

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12
Q

What important GI symptom is diverticular disease a common cause of?

A
  • lower GI bleeding
  • the small blood vessels are stretched over dome of diverticula
  • can rupture causing bleeding
  • bleeding from diverticula is typically painless and spontaneous
    • in most cases blood loss from diverticula is small
    • occasionally it may be massive
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13
Q

What other disease may diverticular disease also mimic and how do we rule this out?

A
  • may clinically closely mimic colorectal cancer
  • intermittent abdo pain + altered bowel habit
  • both conditions affect broadly similar age groups
  • positive FOB and iron deficiency anaemia (due to ongoing bleeding from diverticula)

‘Diverticular’ strictures should be biopsied to rule out colon carcinoma

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14
Q

What is the management of diverticulitis?

A
  • mild attacks treated w/ oral Abx
  • more significant episodes managed in hospital
  • pts are made NBM, IV fluids + IV Abx (a cephalosporin + metronidazole) given
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15
Q

What investigations can be done for diverticulitis?

A
  • FBC → raised WCC
  • CRP → raised
  • Erect CXR → may show pneumopertioneum (perforation)
  • AXR → dilated bowel loops, obstruction or abscesses
  • CT → best modality for suspected abscesses
  • Colonoscopy → avoided initially due to inc risk of perforation in diverticulitis
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