Overview
Diverticular disease
A diverticulum (plural: diverticula) is an out-pouching developed from an organ that is tube- or sac-shaped, such as in the colon.
Diverticulosis describes the presence of diverticula without symptoms.
Diverticular disease describes the presence of diverticula that cause symptoms, such as intermittent abdominal pain without inflammation/infection.
Colonic diverticula are sac-like protrusions of the colon that are most common in the sigmoid and descending colon (~85%). They are prone to inflammation, which can lead to perforation, abscess formation, and complications including fistulae. In Asian people, diverticula may be found in the ascending colon (~15%).
Diverticulitis
Diverticulitis describes the inflammation of a diverticulum, often caused by infection, causing severe abdominal pain, systemic upset (e.g. fever and malaise), and occasionally rectal bleeding.
It can be described as ‘uncomplicated’ if there are no signs of acute abdomen, perforation, or abscess formation and ‘complicated’ if these are present or other complications are seen, such as obstruction or fistulae.
Pathophysiology
Diverticula are thought to form due to increased pressure inside the colon, resulting in weaker parts of the colon wall protruding. They are associated with a low-fibre diet, constipation, and obesity, which can increase intra-colonic pressure by slowing transit time. They are prone to inflammation due to infection.
Epidemiology
- Diverticulosis is more common with age. It is present in up to 10% of people >45 years old and this increases to ~80% in people >85 years old
- In people with diverticulosis, the lifetime risk of developing acute diverticulitis is ~4%
Risk Factors
Risk factors include:
- Older age – usually >45 years old
- Family history
- Low-fibre diet
- Obesity
- Sedentary lifestyle
- Smoking
- Diets rich in red meat
Presentation
Overview
Features of acute diverticulitis include:
- Severe, constant, abdominal pain in the lower left quadrant (over the sigmoid colon):
- In Asian people, this may be present in the lower right quadrant
- Localised peritonism may be seen
- A palpable, tender mass may be present
- Nausea and vomiting – this can be due to ileus or obstruction
- Changes in bowel habit – commonly constipation, but diarrhoea can occur
- Rectal bleeding – mucus may also be passed
- Dysuria – due to irritation of the bladder if it is adjacent to the site of inflammation
- Complications may be present – discussed below
Investigations
Overview
Some investigations and their findings include:
- Full blood count (FBC) – may show leukocytosis and neutrophilia
- C-reactive protein (CRP) – non-specific, may be elevated
- Erect chest X-ray – to look for pneumoperitoneum, which may be seen if perforation occurs
- Abdominal X-ray – may show evidence of obstruction (e.g. dilated bowel loops)
- CT abdomen – may identify bowel wall thickening
Referral
If any of the following are present, the person should have a same-day admission to the hospital:
- Uncontrollable abdominal pain and features suggesting a complication
- Dehydration/at risk of dehydration and cannot tolerate oral fluids at home
- Cannot tolerate oral antibiotics at home
- >65 years old
- Has a significant comorbidity or immunosuppression
Management
Overview
In mild cases of acute diverticulitis where the person does not reach the criteria for hospital admission, treatment with oral antibiotics is offered and the patient is reassessed (usually within 72 hours:
- 1st-line: oral co-amoxiclav
- If allergic/unsuitable: cefalexin + metronidazole or trimethoprim + metronidazole
If symptoms do not settle within 72 hours or the episode is severe, the patient should be admitted for IV antibiotics:
- 1st-line: IV co-amoxiclav
- Other options: cefuroxime + metronidazole or amoxicillin + gentamicin + metronidazole or ciprofloxacin + metronidazole
In some cases, surgery may be necessary, such as abscess drainage or resection.
Complications
Perforation and peritonitis – inflammation may cause the colonic wall to perforate, resulting in inflammatory/infective material entering the abdominal cavity, which can cause sepsis and increase mortality. Suggestive features include rigidity, guarding, rebound tenderness, and a lack of improvement with treatment.
Abscess formation – a tender, palpable abdominal/peri-rectal mass on examination may suggest the presence of an abscess, which may require surgical drainage if unresponsive to antibiotics.
Haemorrhage – bleeding may occur if blood vessels supplying the bowel run over the inflamed diverticula. In around 3/10 people, this can cause massive bleeding requiring emergency transfusion.
Fistula formation – inflammation can cause fistulae to form, particularly when an abscess ruptures into surrounding structures, particularly colovesical fistulae (from the colon to the bladder), leading to pneumaturia and faecal matter in the urine. Other types, such as colovaginal (which can cause the passage of faeces from the vagina) and colouterine fistulae, may form. These require surgery.
Intestinal obstruction – this may be due to acute diverticular inflammation or fibrosis/scarring from recurrent episodes of inflammation. This may present with abdominal distention, absolute constipation, nausea, and vomiting.
Sepsis – bacteraemia can occur, which can result in septic shock, which may cause tachycardia, tachypnoea, hypotension, hypothermia, oliguria/anuria, and skin discolouration.
Prognosis
Most cases of uncomplicated diverticulitis resolve with medical treatment and do not require surgery, however, recurrence is common (in around 1/3 of people, often within 5 years).
