A diverticulum is an outpouching of the bowel wall that is composed of mucosa. There are three important and subtly different manifestations:
- Diverticulosis – the presence of diverticulum (most commonly within the sigmoid colon).
- 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 (1.6:1) and is most prevalent in developed countries.
In an aging bowel that has naturally become weakened in certain areas over time, the movement of stool will cause an increase in luminal pressure.
This results in a protrusion or 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 and cause peritonitis.
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 diverticula remain asymptomatic, and are only found incidentally, such as during routine colonoscopy.
A patient with simple diverticular disease may present with left lower abdominal pain (typically a colicky pain, exacerbated by eating and relieved by defecation), altered bowel habit, nausea, or flatulence.
Diverticulitis can present with a wide spectrum of clinical features depending 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).
- If a patient is taking steroid medication, this can mask the symptoms of diverticulitis, even if it has perforated.
- PR bleeding – usually sudden and sometimes painless
- Large amount of blood and blood clots may be passed, even with minimal pain
- Anorexia, nausea, or vomiting
- Clinical features of sepsis
A PR examination may reveal a mass, secondary to abscess formation.
In severe or chronic cases, a fistula may have formed. Colovesical fistula can present with pneumoturia, faecaluria, or recurrent UTIs, whilst colovaginal fistulas can present with copious vaginal discharge or recurrent vaginal infections.
The important differential diagnoses for diverticular disease include inflammatory bowel disease or bowel cancer.
It is therefore important to investigate any patient with suspected diverticular disease with an appropriate imaging study for example flexible sigmoidoscopy.
Other causes of abdominal pain should be sought including appendicitis, mesenteric ischaemia, gynaecological causes or renal stones.
Complications of Diverticular Disease
Younger patients with diverticular disease have been shown to have more active disease with higher re-occurrence and complication rates.
Recurrent or chronic diverticular disease can result in the development of:
- Bowel obstruction, secondary to stricture formation and can be managed either via stenting or bowel resection
- Pericolic abscesses, which can be treated initially with antibiotics and bowel rest, before CT guided drainage or a laparoscopic washout are trialled as further management options
- Fistula formation, with colovesical or colovaginal (as discussed), yet often requiring surgical resection and repair
Any patient with suspected diverticular disease should have initial routine blood tests performed: FBC (for anaemia, secondary to chronic blood loss), U&Es, clotting, LFTs, and Group & Save or Crossmatch (pending degree of blood loss)
In severe cases or in suspected diverticulitis, a blood gas (either ABG or VBG) will be useful to assess the lactate level, representing sepsis or bowel ischaemia.
A urine dipstick may prove helpful to exclude any urological causes (e.g. left renal colic or pyelonephritis).
In a patient with suspected diverticular disease, a flexible sigmoidoscopy is a good initial approach as this will identify any obvious rectosigmoidal lesion. A sigmoidoscopy or colonoscopy should never be performed in any presenting cases of suspected diverticulitis, due to the increased risk of perforation.
Dependent on clinical findings, an abdominal X-ray (AXR) may be required to exclude obstruction. An erect chest X-ray (eCXR) should also be requested if a perforation is suspected (assess for air under the diaphragm).
CT scan of the abdomen-pelvis can provide high level of accuracy in diagnosing symptomatic diverticular disease but is better utilised in patients where perforation or an alternative diagnosis is suspected.
Contrast studies can be used to investigate any fistula that have developed.
In the UK, patients with mild uncomplicated diverticulitis can be managed at home with antibiotics, analgesia, and encouraging intake of clear fluids. Paracetamol is recommended as first line analgesia, as opioid-based analgesia may cause constipation and worsen the clinical course of the diverticular disease.
Hospital guidance varies regarding admitting patients with diverticular disease. However, the following features should be sought:
- Pain is not controlled with simple analgesia or concerns of dehydration
- The patient has significant co-morbidities or is immunocompromised
- Significant PR bleeding that may require transfusion
- Suspicion of sepsis/peritonitis
- Symptoms persist for longer than 48 hours at home with conservative management
Depending on the severity of the diverticular disease, inpatient management can be either conservative or surgical.
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.
Investigations should be ordered concurrently to confirm the suspected diverticulitis and assess severity. Any sepsis suspected, secondary to the diverticulitis, requires managing accordingly.
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 embolization, intra-arterial vasopressin, or surgical resection may be needed.
Note: If a second bleeding episode occurs there is a significant chance of a third episode (up to 50%).
Surgery is eventually required in 15-30% of patients admitted. Indications for emergency surgery include:
- Perforation with faecal peritonitis (mortality rate up to 50%)
- 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).
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
*Lavage is often done in younger patients, those with higher BMIs, or low ASA grades, however no definitive guidelines exist for preferred surgical intervention
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.