Diverticula can occur throughout the gastrointestinal tract, but are seen most commonly in the sigmoid and descending colon. A diverticulum consists of a herniation of mucosa through the thickened colonic muscle. Diverticula vary from solitary findings to many hundreds. They are typically 5-10 mm in diameter but can exceed 2 cm.
- Diverticulosis is defined as the presence of diverticula which are asymptomatic.
- Diverticular disease is defined as diverticula associated with symptoms.
- Diverticulitis is defined as evidence of diverticular inflammation (fever, tachycardia) with or without localised symptoms and signs.
- The prevalence of perforated sigmoid diverticular disease in developed countries increased from 2.4/100,000 in 1986, to 3.8/100,000 in 2000.
- Approximately 50% of all people have diverticula by the time they are 50 years of age, and nearly 70% of all people have diverticula by the time they are 80 years of age.
- Approximately 75% of people with diverticula have asymptomatic diverticulosis; of the 25% of people with diverticula who develop symptomatic diverticular disease, approximately 75% will have at least one episode of diverticulitis.
- Diverticular disease is rare in people younger than 40 years. Disease is more virulent in young patients, with a high risk of recurrences or complications.
- The disorder is rare in rural Africa and Asia, with the highest prevalence seen in the USA, Europe, and Australia.
- The most common fistula is colovesicular and then colovaginal fistulas. Colo-enteric, colo-uterine, colo-ureteral and colocutaneous fistulas arise much less often.
- The main risk factors are age over 50 years and low dietary fibre.
- Obesity is an important risk factor in young people.
- Complicated diverticular disease has an increased frequency in patients who smoke, use non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol, and those who are obese and have low-fibre diets.
Uncomplicated diverticular disease
- Frequently an incidental finding during assessment of a patient for another reason, such as routine screening for colon cancer.
- Patients can present with nonspecific abdominal complaints - eg, lower abdominal pain, usually left-sided. Any further features of inflammation, such as pyrexia or neutrophilia, may indicate diverticulitis.
- Pain is generally exacerbated by eating and diminished with defecation or flatus.
- Other symptoms, such as bloating, constipation or rectal bleeding, may also occur.
- Examination may reveal fullness or mild tenderness in the left lower quadrant.
- Generally presents with left lower quadrant pain. Asian patients have predominantly right-sided diverticula and will usually present with right lower quadrant pain.
- Pain may be intermittent or constant and may be associated with a change in bowel habits.
- Fever and tachycardia are present in most patients; hypotension and shock are unusual.
- Anorexia, nausea and vomiting may occur.
- Examination usually reveals localised tenderness and, occasionally, a palpable mass. Bowel sounds are often reduced but may be normal in mild cases or increased with obstruction.
- Rectal examination may reveal tenderness or a mass, especially with a low-lying pelvic abscess.
- One third of patients who develop diverticulitis will develop further complications (perforation, abscess, fistula, stricture/obstruction):
- An abscess may be pericolic or more extensive. Clinical signs of an abscess include a tender mass or persistent fever despite an adequate trial of antibiotics.
- Free perforation into the peritoneum, causing frank peritonitis, can be life-threatening but is rare.
- During an episode of acute diverticulitis, partial colonic obstruction or colonic pseudo-obstruction may occur.
- Recurrent episodes of diverticulitis may cause progressive fibrosis and stricturing of the colonic wall, eventually leading to complete obstruction.
- Colovesicular fistulas often present with pneumaturia and faecaluria. The passage of stool or flatus via the vagina is pathognomonic of a colovaginal fistula, which may also present with frequent vaginal infections or copious vaginal discharge.
- Diverticular bleeding is a common cause of lower gastrointestinal haemorrhage. Severe haemorrhage can arise in 3-5% of patients with diverticulosis. The site of bleeding may more often be located in the proximal colon.
- Presentation is usually abrupt painless bleeding. The patient may have mild lower abdominal cramps or the urge to defecate, followed by passage of a large amount of red or maroon blood or clots. Melaena may occur but is uncommon.
- Haemorrhage ceases spontaneously in 70-80% of patients. Re-bleeding rates range from 22-38%.
- Other causes of acute abdominal pain (including other abdominal, urological, and gynaecological causes) must be considered and excluded.
- Symptomatic diverticular disease may closely resemble irritable bowel syndrome.
- The differential diagnosis of diverticulitis includes acute appendicitis, Crohn's disease and colorectal cancer.
- Elderly people with diverticulosis are also at risk of ischaemic colitis. Features helpful to differentiate between these disorders include presence of thumb-printing on abdominal radiographs and haematochezia (passage of bright red blood with bowel movements), both suggesting ischaemia.
- Gynaecological disorders, such as ruptured ovarian cysts, ovarian torsion, ectopic pregnancy, or pelvic inflammatory disease, can resemble acute diverticulitis in female patients. Pelvic ultrasound can be helpful in obtaining an accurate diagnosis.
- Other forms of colitis, such as pseudomembranous or amoebic, can also mimic diverticulitis.
- A thorough investigation, including colonoscopy, may be required for patients with symptomatic disease to confirm the diagnosis and rule out other possible diagnoses, especially bowel cancer.
- Initial blood haematology should be normal in patients with uncomplicated diverticular disease. The white cell count is often raised in patients with diverticulitis or abscess. Bleeding may cause a raised platelet count and anaemia.
- Uncomplicated diverticular disease:
- Barium enema provides information on number and location of colonic diverticula, but cannot discern clinical relevance. Inaccurate findings have been reported in nearly a third of patients with diverticulosis.
- CXR with the patient upright can aid detection of pneumoperitoneum.
- Abdominal X-rays may demonstrate small or large bowel dilation or ileus, pneumoperitoneum, bowel obstruction, or soft tissue densities suggesting abscesses.
- Contrast enemas: limited value; findings suggestive of diverticulitis include extravasated contrast material outlining an abscess cavity, intramural sinus tract or fistula.
- CT scanning with intravenous, oral or rectal contrast: sensitivities and specificities for CT are significantly better than for contrast enemas. When an abscess is suspected, CT scanning is the best modality for making the diagnosis and following its course.
- Because of risk of perforation, endoscopy is generally avoided in initial assessment of the patient with acute diverticulitis. Its use should be restricted to situations when the diagnosis in unclear, to exclude other possible diagnoses.
- Cystoscopy, cystography and contrast radiographs or methylthioninium chloride (methylene blue) studies can show colovesicular fistula tracts.
- Flexible sigmoidoscopy is an appropriate initial approach to rule out an obvious rectosigmoid lesion.
- If no cause is identified, further assessment with non-invasive (nuclear scintigraphy) or invasive (angiography, colonoscopy) techniques can be undertaken in an attempt to localise and treat the bleeding source.
- No treatment or follow-up needs to be offered to patients who are asymptomatic, although there may be a prophylactic benefit of a high-fibre diet. The risk of perforation may be increased by the use of NSAIDs and long-term use of opioids.
- Calcium-channel blockers are associated with a reduction in diverticular perforation but there is insufficient evidence to recommend their use.
- No rationale exists for use of antibiotics or narcotic analgesics in uncomplicated diverticular disease.
- Arrange admission for people with significant blood loss, as blood transfusion may be required.
- Advise a high-fibre diet; the diet should contain whole grains, fruit and vegetables.
- Adequate fluid intake is also very important.
- Bulk-forming laxatives (eg, ispaghula, sterculia, methylcellulose) may be beneficial to supplement the diet if a high-fibre diet is not effective or acceptable, or if constipation or diarrhoea occurs.
- Other medication such as antispasmodics, osmotic laxatives, or aminosalicylates is not recommended.
- Paracetamol should be used for pain if required.
- Hospital admission is required for people with diverticulitis when:
- Pain cannot be managed with paracetamol.
- Hydration cannot be easily maintained with oral fluids, or oral antibiotics cannot be tolerated.
- The person is frail or has a significant comorbidity that is likely to complicate their recovery, particularly if they are immunocompromised.
- There is rectal bleeding that may require transfusion.
- Perforation and peritonitis occur.
- An intra-abdominal abscess or fistula develops.
- Symptoms persist after 48 hours despite conservative management at home.
- For people managed at home:
- Broad-spectrum antibiotics should be prescribed to cover anaerobes and Gram-negative rods - eg, co-amoxiclav or a combination of ciprofloxacin and metronidazole (if allergic to penicillin). Antibiotic treatment should last for at least seven days if used; however, recent evidence suggests that this should be reserved for the treatment of complicated rather than simple diverticulitis.
- Paracetamol should be used for pain.
- Recommend clear liquids only; gradually reintroduce solid food as symptoms improve over 2-3 days.
- Review within 48 hours, or sooner if symptoms deteriorate. Hospital admission should be arranged if symptoms persist or deteriorate.
- Mesalazine has been shown to be more effective in improving the severity of symptoms, bowel habit, and in preventing symptomatic recurrence of diverticulitis, than antibiotics alone.
- Most patients admitted with acute diverticulitis will respond to conservative treatment, but 15-30% will need surgery.
- The indications for surgery are:
- Purulent or faecal peritonitis.
- Uncontrolled sepsis.
- Inability to exclude carcinoma.
- Free perforation with generalised peritonitis, although uncommon, carries a high mortality rate (up to 35%) and needs urgent surgical intervention.
- Risk of recurrent symptoms after an attack of acute diverticulitis is about one in three. Recurrent attacks are less likely to respond to medical treatment and they have a high mortality rate. Although often recommended, recent evidence indicates that prophylactic resection has little impact in preventing subsequent complications, as most patients who need urgent surgery have no history of diverticular disease.
- For emergency surgery, a recent multicentre randomised controlled trial found that a one-stage procedure (primary anastomosis) significantly reduced rates of postoperative peritonitis and emergency re-operation compared with a two-stage procedure (formation of an end colostomy with oversewing of the rectal stump - Hartmann's procedure).
Management of further complications
- Small pericolic abscesses can generally be treated conservatively with continued antibiotics and bowel rest.
- In patients in whom surgery is needed, a single-stage resection and anastomosis can generally be done. For those with distant or unresolving abscesses, drainage is indicated.
- CT-guided percutaneous drainage of abdominal abscesses is now used in preference to surgery when feasible.
- Colovesical fistulas: single-stage resection with fistula closure can be undertaken in most patients.
- Colovaginal fistulas: surgical resection of the diseased colon with repair of the vagina.
- Acute diverticulitis may cause small bowel obstruction or ileus, which will usually improve as the inflammation subsides with effective treatment.
- Strictures in which malignant disease cannot be excluded should be resected.
- A trial of endoscopic balloon dilation can be attempted in patients in whom neoplasm can be excluded.
- Stenting can provide temporary decompression, allowing for bowel preparation and subsequent single-stage resection without diversion.
- Immediate fluid and blood product resuscitation is often required.
- For most patients, diverticular bleeding is self-limited. Subsequent colonoscopy should be performed to establish the source of the bleeding and to exclude neoplasia.
- Intra-arterial vasopressin at angiography can control haemorrhage in more than 90% of patients. The benefit is usually only temporary but may allow time to prepare the patient adequately for surgery.
- Angiographic embolisation of very distal bleeding branches is also effective and safe.
- Surgery in lower gastrointestinal bleeding is usually reserved until endoscopic or angiographic treatments fail.
- Segmental resection is most usually done if the bleeding site is clearly identified from a therapeutically unsuccessful angiographic or endoscopic procedure. In patients with persistent bleeding and no angiographic or endoscopic identification of a definite bleeding site, subtotal colectomy may be required.
- The chance of a third bleeding episode can be as high as 50%, so many authorities recommend surgical resection after a second bleeding episode.
- Approximately three quarters of patients with anatomical diverticulosis remain asymptomatic.
- Most complications of diverticulitis are associated with the initial attack, after which the disease tends to run a benign course.
- Mortality and morbidity are related to complications of diverticulosis, which are mainly diverticulitis and lower gastrointestinal bleeding. These occur in 10-20% of patients with diverticulosis during their lifetime.
- Morbidity has traditionally been reported to be worse in younger patients, but this has not been shown to be true.
- Dietary fibre may prevent development of diverticular disease but, once symptoms develop, the benefit from fibre supplementation is unclear.
- Physical exercise has also been shown to help prevent the development of diverticular disease.
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