Diverticular Disease

Original Author: Sarah Wilson
Last Updated: March 25, 2019
Revisions: 23


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 the condition:

  • 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 men more than women and is more prevalent in developed countries.

Diverticular disease is the 8th most frequent outpatient gastrointestinal diagnosis made in the US, with nearly 3 million associated health care visits occurring each year.


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.

Bacteria can overgrow within the outpouchings, leading to inflammation of the diverticulum. If a diverticulum perforates into the abdominal cavity, a diffuse peritonitis will result, however if the infection remains contained within diverticula (covered by mesentery), a phlegmon or abscess can develop, which presents with localised peritoneal signs.

In severe or chronic cases, fistulae can form, most commonly as colovesical or colovaginal. Younger patients with diverticular disease have been shown to have more active disease with higher re-occurrence and complication rates.

Fig. 1 - Laparoscopic view of diverticula in the sigmoid colon

Figure 1 – Laparoscopic view of diverticula in the sigmoid colon

Diverticulitis is classified as either simple or complicated. Complicated diverticulitis refers to abscess presence, fistula formation, stricture, or free perforation, whilst simple diverticulitis describes inflammation without these features.

Risk Factors

The risk factors for the formation of diverticulum include low dietary fibre intake, obesity (in younger patients), smoking, family history, and NSAID use.

Clinical Features

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 diverticular disease may present with left lower abdominal pain (typically a colicky pain, relieved by defecation), altered bowel habit, nausea, or flatulence.

Diverticulitis will present with abdominal pain and localised tenderness, classically in the left iliac fossa*, alongside potential pyrexia, nausea +/- vomiting, PR bleeding (usually sudden and painless), or anorexia. PR exam is typically unremarkable.

perforated diverticulum will present with signs of localised peritonism or generalised peritonitis

*If a patient is taking corticosteroids or immunosuppressants, this can mask the symptoms of diverticulitis, even if perforated; in patients with a redundant sigmoid colon, pain may often be in the right lower quadrant or suprapubic are

Complications of Diverticular Disease

Complications of diverticular disease develop in severe, 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

Differential Diagnosis

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.


Laboratory Tests

Any patient with suspected diverticular disease should have initial routine blood tests performed, including FBC and CRP.

Those with suspected diverticulitis, should also have a routine bloods, alongside a Group and Save and a venous blood gas, to aid clinical assessment. A urine dipstick may prove helpful to exclude any urological causes.


In patients with suspected uncomplicated diverticular disease, a flexible sigmoidoscopy* is a good initial approach as this will identify any obvious rectosigmoidal lesion.

For cases of suspected diverticulitis, a CT abdo-pelvis scan (Fig. 2) should be performed, as they have a high level of sensitivity for detecting the condition and any complications that made have developed.

CT findings that can suggest diverticulitis include thickening of the colonic wall, pericolonic fat stranding, abscesses, localised air bubbles, or free air; a “microperforation” is a radiologic diagnosis that reflects a localised perforation and inflammation.

*A sigmoidoscopy or colonoscopy should never be performed in any presenting cases of suspected diverticulitis, due to the increased risk of perforation.

Fig. 3 - CT scan for varying degrees of diverticular disease (1) diverticulum in the sigmoid colon (2) degree of diverticulitis present (3) abscess formation, secondary to ongoing diverticulitis

Figure 2 – CT scan for varying degrees of diverticular disease (1) diverticulum in the sigmoid colon (2) degree of diverticulitis present (3) abscess formation, secondary to ongoing diverticulitis

Disease Staging

Acute diverticulitis can be staged using the Hinchey Classification, a classification system based on CT findings. It can be used to aid clinical management and importantly higher stages are associated with higher morbidity and mortality.

Stage Computed Tomography Description 
Stage 1 Phlegmon (1a) or diverticulitis with pericolic or mesenteric abscess (1b)
Stage 2 Diverticulitis with walled off pelvic abscess
Stage 3 Diverticulitis with generalised purulent peritonitis
Stage 4 Diverticulitis with generalised faecal peritonitis

Table 1 – Hinchey Classification of Acute Diverticulitis


Patients with mild uncomplicated diverticular disease can often be managed as an outpatient with simple analgesia and encouraging oral fluid intake.

Hospital admission may be required in cases of uncontrolled pain, concerns of dehydration, significant co-morbidities or immunocompromised, significant PR bleeding, or symptoms persisting for longer than 48 hours despite conservative management

Management of Diverticulitis

Conservative Management

Conservative management for a patient with suspected or confirmed diverticulitis is with  IV antibiotics, IV fluids, bowel rest (only clear fluids orally), and analgesia. Uncomplicated cases can also be managed in the outpatient setting, especially if the patient is systemically otherwise well and no significant co-morbidities or immunosuppression.

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

Symptoms typically improve within 2-3 days after the initiation of treatment. Often the diet can be advanced from clear liquids to a low-residue diet, and IV antibiotic therapy swapped to oral treatment. Clinical deterioration or lack of improvement should prompt repeat imaging.

Surgical Management

Surgery is eventually required in 15-30% of patients admitted.

  • Emergency surgery is required in those with perforation with faecal peritonitis (mortality rate up to 50%) or overwhelming sepsis
  • Urgent surgery is required in those failing to improve despite medical therapy or percutaneous drainage

Surgical intervention will typically be via bowel resection, typically via a Hartmann’s procedure, however resection with primary anastomosis and loop ileostomy may also be attempted. Laparoscopic peritoneal lavage* can be trialled, however is not currently advocated in clinical guidelines.

*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.

A Hartmann’s procedure (Fig. 3) involves resection of the sigmoid colon, with the formation of an end colostomy and closure of the rectal stump. An anastomosis with reversal of colostomy may be possible at a later date.

The before and after of the bowel following a Hartmann's Procedure

Figure 3 – Schematic demonstrating a Hartmann’s procedure, before and after

Recurrence of diverticulitis after first episode is around 10-35%. Elective segmental resection may be performed in patients with recurrent disease,

Unless a recent endoscopy has been performed, outpatient colonoscopy following resolution of diverticulitis should be arranged.

Key Points

  • 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


Question 1 / 4
All of the following are risk factors for diverticulosis except?


Question 2 / 4
A patient known to have diverticulosis and recurrent bouts of diverticulitis presents to the emergency room with a one day history of fever, chills, and significant generalised abdominal pain and tenderness. Which one of the following is likely to be the cause?


Question 3 / 4
A patient is admitted with extensive PR bleeding secondary to diverticulitis. Which of the following definitive management options would not be suitable?


Question 4 / 4
Which of the following is not an indication for surgical intervention in patients with diverticulitis?


Further Reading

Randomized clinical trial of antibiotics in acute uncomplicated diverticulitis
AVOD Study Group, British Journal of Surgery

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