A diverticulum is an outpouching of the bowel wall. They are most commonly found in the sigmoid colon, but can be present throughout the large and small bowel.
There are four different manifestations of the condition:
- Diverticulosis – the presence of diverticula
- Diverticular disease – symptomatic diverticula
- Diverticulitis – inflammation of the diverticula
- Diverticular bleed – where the diverticulum erodes into a vessel and causes a large volume painless bleed (discussed here)
Diverticulosis is present in around 50% of >50yrs and 70% of >80yrs, but only 25% of these cases become symptomatic. The disease affects men more than women and is more prevalent in developed countries.
In an aging bowel that has naturally become weakened 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 (at the junctions of the triangular muscle sheets and blood vessels penetrate to supply the bowel wall).
Bacteria can overgrow within the outpouchings, leading to inflammation of the diverticulum (diverticulitis) which can sometimes perforate, potentially leading to diffuse peritonitis sepsis and death.
In chronic cases, fistulae can form, most commonly colovesical or colovaginal. Younger patients with diverticular disease have been shown to have more active disease with higher re-occurrence and complication rates.
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.
The risk factors for the formation of diverticulum include low dietary fibre intake, obesity (in younger patients), smoking, family history, and NSAID use.
A large proportion of individuals with diverticulosis remain asymptomatic and are only found incidentally, such as during routine colonoscopy or CT imaging. These are often of no clinical significance
Features of diverticular pain include an intermittent lower abdominal pain, typically colicky in nature and may be relieved by defecation, an altered bowel habit, associated nausea, and flatulence.
Diverticulitis however will present with acute abdominal pain*, typically sharp in nature and normally localised in the left iliac fossa pain, worsened by movement and with localised tenderness. Features of systemic upset, such as decreased appetite, pyrexia, or nausea, may also be present.
A perforated diverticulum will present with signs of localised peritonism or generalised peritonitis. These patients are frequently extremely unwell and the condition is frequently fatal.
*If a patient is taking corticosteroids or immunosuppressants, this can mask the symptoms of diverticulitis, even if perforated; in patients with a floppy redundant sigmoid colon, pain may often be in the right lower quadrant or suprapubic area
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 (gas bubbles in the urine), passing faecal matter in the urine) and 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
The important differential diagnoses for diverticular disease are inflammatory bowel disease or bowel cancer.
Other causes of abdominal pain should also be sought including mesenteric ischaemia, gynaecological causes, or renal stones.
Any patient with suspected diverticular disease should have initial routine blood tests performed, including FBC and CRP, plus potentially a faecal calprotectin in certain cases.
Those with suspected diverticulitis, should also have 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 abdomen-pelvis scan (Fig. 2) is the investigation of choice. CT findings that can suggest diverticulitis include thickening of the colonic wall, pericolonic fat stranding, abscesses, localised air bubbles, or free air
*A colonoscopy should never be performed in any presenting cases of suspected diverticulitis, due to the increased risk of perforation
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
Conservative management for a patient with suspected or confirmed diverticulitis is with IV antibiotics, IV fluids, bowel rest (only clear fluids orally), and analgesia. Some uncomplicated cases of diverticular disease can also be managed in the outpatient setting, especially if the patient is systemically otherwise well and no significant co-morbidities or immunosuppression.
Diverticular bleeds 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. Any significant bleeding will need appropriate resuscitation, with IV fluids and blood products, and stabilisation.
Symptoms typically improve within 2-3 days after the initiation of treatment for uncomplicated cases. 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.
*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
Surgical intervention is required in those with perforation with faecal peritonitis or overwhelming sepsis. This is a major procedure and usually involves a Hartmann’s procedure (a sigmoid colectomy with formation of an end colostomy. Fig. 3); an anastomosis with reversal of colostomy may be possible at a later date.
Resection with primary anastomosis and loop ileostomy may sometimes be attempted. Laparoscopic peritoneal lavage* can be trialled, however is not currently advocated in clinical guidelines.
*A 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
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 flexible sigmoidoscopy within 6 weeks should be arranged.
- The four different manifestations of diverticula are diverticulosis, diverticular disease, diverticulitis, and diverticular bleeds
- Patients with perforated diverticular disease are surgical emergencies and require urgent fluids, antibiotics and emergency surgery
- Most cases of uncomplicated 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