Diverticular Disease, Diverticulitis, and Abdominal Abscess

Diverticula

Sac-like herniations of mucosa through the smooth muscular colonic wall, often in natural openings created by the vasa recta or vessels.

  • Around 50% of the population have diverticula by age 50 and 70% by age 80.

Diverticulosis

Diverticula present without any symptoms.

  • Around 75% of people with diverticula are asymptomatic.

Diverticular Disease

Condition where diverticula cause intermittent pain, but without any signs of acute infection or inflammation

Diverticulitis

Infection and inflammation of the diverticula, usually causing marked pain, fever and malaise.  It can be complicated by abscess formation, perforation or fistula.

  • Of the 25% of people with diverticula who develop symptomatic disease, 75% will have at least one episode of diverticulitis

Pathophysiology

  • The vasa recta that penetrate the bowel wall create areas of weakness through which a portion of colonic mucosa and submucosa can herniate.
  • The sigmoid colon is commonly affected, probably due to its small diameter and thus higher intraluminal pressures.
  • The pathophysiology that causes symptoms is poorly understood
    • Damage to the vasa recta vessels may result in inflammation
    • It has also been thought that obstruction of the diverticula with faecal matter can cause an acute inflammatory reaction.
    • It has also been suggested that microperforation of diverticula could be a cause of diverticular disease symptoms (i.e. without causing an acute diverticulitis)
    • In any case, acute diverticulitis is thought to be a result of a perforated diverticulum.
    • Abscess formation is not uncommon

Presentation

  • Diverticulosis, by definition, is asymptomatic and is usually an incidental finding on investigation
  • Diverticular disease
    • Intermittent pain in the (left) lower abdomen, which is tender on examination.  Pain may be brought on with eating and may be relieved by bowel movements
    • Altered bowel habit- commonly constipation but diarrhoea can be a symptom
    • Bloated feeling
    • mucus discharge
    • PR bleeding- usually fresh or mixed with the stool (haematochezia); can be substantial and will often be the presenting complaint
      • NB diverticular bleeding is usually a single (or infrequent) episode- if frequent/continuous, the cause is unlikely to be diverticular (even if this has been diagnosed)
  • Diverticulitis
    • Constant, severe abdominal pain that may localise to the left iliac fossa.  Tender on examination.
    • Fever is a typical feature (distinguishing from diverticular disease)
    • Nausea, vomiting and anorexia may also be present
    • Urinary symptoms may also be present due to subsequent inflammation of urinary structures.  It is important to ask about this

Investigations

  • Bloods- FBC should be done to check for degree of blood loss (Hb) and inflammatory response (WCC raised in diverticulitis)
  • Flexible sigmoidoscopy/colonoscopy will diagnose diverticulosis (the others are clinical diagnoses)
    • Rarely will a barium enema be used to diagnose diverticular disease (more often a barium study will identify diverticulosis as an incidental finding)
    • CT will also identify diverticula (and is more suitable if the patient has signs of peritonism) but is not first line

Management

  • Diverticulosis does not require any treatment, although a high fibre diet is advised
  • Diverticular disease can usually be managed conservatively with pain relief (avoid NSAIDs and opioids if at all possible due to risk of bleeding and further constipation)
    • Any blood loss should be managed appropriately (usually warranting admission) with fluid resuscitation
  • Diverticulitis
    • People with mild, uncomplicated diverticulitis can be managed at home with pain relief (paracetamol); clear fluids; and oral antibiotics (co-amoxiclav or, if allergic, ciprofloxacin and metronidazole) for at least 7 days
      • Advise clear fluids only (no hard diet) until symptoms improve.  If symptoms don’t improve/worsen, consider admission
    • Arrange admission if:
      • Pain is not managed with paracetamol
      • Hydration cannot be maintained with oral fluids or oral antibiotics not tolerated
      • There is significant co-morbidity likely to affect their recovery
      • If there is bleeding that might require transfusion
      • Perforation/peritonitis
      • Any evidence of a fistula (e.g. faecal discharge via waterworks)
      • Any swelling suggestive of an intra-abdominal abscess
    • Management in hospital is similar i.e. with fluid resuscitation and antibiotics (IV amoxicillin, metronidazole +/- gentamycin)
    • Surgery is rarely offered for removal of diverticula, but may be required for the drainage/removal of abscesses, repair of fistulae, and management of peritonitis

Abdominal Abscess

  • Most commonly caused by perforated appendicitis/diverticulitis or perforated peptic ulcer
    • Other causes include gangrenous cholecystitis; mesenteric ischaemia with infarction; and pancreatitis or pancreatic necrosis
    • Occasionally, an abscess may be iatrogenic (post-surgery)
  • Infective organisms that cause the abscess are mixed (aerobic/anaerobic)- most commonly E coli and Bacteroides
  • Pain is usually a feature.  Signs of infection (particularly a spiking fever, but also other signs of SIRS/Sepsis e.g. hypotension, tachycardia etc may also be present)
    • Occasionally change in bowel habit (important to ask)
    • Also ask about urinary symptoms (pelvic abscess) and chest symptoms (subphrenic) e.g. hiccuping, pleuritic pain
  • A tender, hot mass may (or may not) be palpable on examination
  • CT scan and/or ultrasound should be carried out to localise the abscess.  FBC/U&E/cultures should also be taken.
  • Drainage depends on clinical severity.  In either case broad spectrum antiobiotic treatments will also be needed (see above)
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