A diverticulum is an outpouching of the bowel wall composed of mucosa. They are most commonly found in the sigmoid colon, but can be present throughout the large bowel and even (albeit less commonly) small bowel.
There are three different manifestations of diverticiulum:
- Diverticulosis – the presence of diverticulum
- Diverticular disease – symptomatic diverticulum
- Diverticulitis – inflammation of the diverticulum
Diverticulosis is present in around 50% of >50yrs and 70% of >80yrs, yet only 25% of these cases become symptomatic. The disease affects more men than women and is more prevalent in developed countries.
In an aging bowel that has naturally become weakened in certain areas over time, the movement of stool within the lumen will cause an increase in luminal pressure. This results in an outpouching of the mucosa through the weaker areas of the bowel wall, creating pockets in which bowel contents, including bacteria, can accumulate. The diverticulum, when inflamed, can perforate.
The risk factors for the formation of diverticulum include low dietary fibre intake, obesity (in younger patients), smoking, family history, and NSAIDs use.
A large proportion of individuals with diverticulosis remain asymptomatic and are only found incidentally, such as during routine colonoscopy or CT imaging.
A patient with simple diverticular disease may present with left lower abdominal pain (typically a colicky pain, relieved by defecation), altered bowel habit, nausea, or flatulence.
Diverticulitis can present with a wide spectrum of clinical features, dependent on the specific complication of the diverticulum, including:
- Abdominal pain and localised tenderness, classically in the left iliac fossa*
- A perforated diverticulum can present with signs of localised peritonism or generalised peritonitis
- PR bleeding, usually sudden and often painless
- Anorexia, nausea or vomiting, or pyrexia
A PR examination is most commonly unremarkable, yet in severe cases of the disease can reveal a tender mass (secondary to abscess formation). In severe or chronic cases, fistulae can form (most commonly colovesical or colovaginal, see below).
*If a patient is taking corticosteroids or immunosuppressants, this can mask the symptoms of diverticulitis, even if perforated
Complications of Diverticular Disease
Complications of diverticular disease develop in recurrent or chronic cases of the condition, such as:
- Pericolic abscess – often treated initially with antibiotics and bowel rest, before CT guided drainage or laparoscopic washout can be trialled as further management options
- Fistula formation – common fistula subtypes include colovesical fistula (often presenting with pneumoturia, faecaluria, or recurrent UTIs) or colovaginal fistulas (often presenting with copious vaginal discharge or recurrent vaginal infections); such fistulas will require surgical resection and repair
- Bowel obstruction – secondary to stricture formation, can be managed through either stenting or bowel resection
Younger patients with diverticular disease have been shown to have more active disease with higher re-occurrence and complication rates.
The important differential diagnoses for diverticular disease are inflammatory bowel disease or bowel cancer.
Other causes of abdominal pain should also be sought including appendicitis, mesenteric ischaemia, gynaecological causes, or renal stones.
Any patient with suspected diverticular disease should have initial routine blood tests performed, including FBC, CRP, and a Group & Save.
In severe cases or in suspected diverticulitis, a blood gas can be useful in aiding clinical assessment. A urine dipstick may prove helpful to assess for any urological causes.
In a patient with suspected diverticular disease, a flexible sigmoidoscopy* is a good initial approach as this will identify any obvious rectosigmoidal lesion.
Dependent on clinical findings, an erect chest radiograph (eCXR) may also be warranted if a perforation is suspected.
A CT abdo-pelvis scan (Fig. 2) can provide high level of accuracy in diagnosing symptomatic diverticular disease and any complications that made have developed, as well as assessing for any alternative diagnoses suspected.
Contrast imaging studies can be used to investigate any fistula that have developed.
*A sigmoidoscopy or colonoscopy should never be performed in any presenting cases of suspected diverticulitis, due to the increased risk of perforation.
Patients with mild uncomplicated diverticular disease can often be managed as an outpatient with analgesia* and encouraging intake of clear fluids.
Hospital guidance varies regarding admitting patients with diverticular disease. However, the following features should be assessed for, which can guide potenial admission:
- Uncontrolled pain with simple analgesia or concerns of dehydration
- The patient has significant co-morbidities or is immunocompromised
- Significant PR bleeding
- Suspicion of peritonitis, warranting imaging and active observation
- Symptoms persisting for longer than 48 hours at home with conservative management
*Simple analgesics are recommended as first line analgesia, as opioid-based analgesia may cause constipation and worsen the clinical course of the diverticular disease
Conservative management for a patient with suspected or confirmed diverticulitis is with broad-spectrum IV antibiotics, IV fluids, bowel rest (only clear fluids orally), and analgesia.
Any significant PR haemorrhage will need resuscitation with IV fluids and blood products. A diverticular bleed in most patients will be self-limiting* however options such as embolisation or surgical resection may be needed if cases do not settle with conservative approaches
*If a second bleeding episode occurs there is a significant chance of further episodes (up to 50%), hence it can be best to discuss early with interventional radiologists for planning further management options
Surgery is eventually required in 15-30% of patients admitted. Indications for emergency surgery include:
- Perforation with faecal peritonitis (mortality rate up to 50%)
- Sepsis, not responding to antibiotic therapy
- Failure to improve with conservative management
Emergency intervention will be either bowel resection (either with primary anastomosis or as a Hartmann’s procedure) or laparoscopic peritoneal lavage* (washout of an abscess).
Lavage is often done in younger patients, those with higher BMIs, or low ASA grades, however no definitive guidelines exist for preferred surgical intervention
*A recent meta-analysis showed no difference between resection vs. lavage for acute perforated diverticulitis in mortality, 30-day reoperations and unplanned readmissions, however lavage was associated with higher rates of intraabdominal abscesses, peritonitis, and increased long-term emergency reoperations.
Elective surgical intervention may be indicated in patients with chronic symptoms, significant co-morbidities, immunosuppression, or recurrent disease. It may also be used in cases where a complicated diverticulitis was initially treated by percutaneous drainage.
A Hartmann’s procedure is an emergency surgical procedure whereby the affected area of colon (sigmoid colon) is resected, with the formation of an end colostomy and the closure of the rectal stump. An anastomosis with reversal of colostomy may be possible at a later date.
- The three different manifestations of diverticiulae are diverticulosis, diverticular disease, and diverticulitis
- Diverticulae formation is most commonly associated with a low-fibre diet
- Diverticulitis can present with abdominal pain, evidence of systemic infection, or painless PR bleeding
- Most cases of diverticulitis can be treated conservatively
- Surgical intervention is warranted in those with evidence of perforation, sepsis not responding to antibiotic therapy, or failure to improve despite conservative management