Diverticular disease

Diverticular disease, or diverticulosis, is a condition where small pouches of mucosa (diverticula) in the bowel wall cause symptoms of abdominal pain and altered bowel habit. Diverticulitis occurs when diverticula become inflamed or infected and may require treatment. Although most people with diverticulosis remain asymptomatic, these conditions cause a considerable morbidity to patients and create a financial burden to healthcare systems – particularly in western countries where they are more prevalent.

Common terms used throughout this article are defined below:

Diverticula: sac-like protrusions of mucosa.

Diverticular disease: diverticula which cause symptoms, such as lower abdominal pain without inflammation or infection.

Diverticulitis: diverticular which become inflamed and can cause infection, resulting in symptoms of lower abdominal pain, pyrexia, malaise and/or rectal bleeding.

Uncomplicated diverticular disease: diverticular inflammation without symptoms of acute abdomen, signs of perforation, strictures or abscess formation.

Complicated diverticular disease: diverticular inflammation with complication(s) – including abscess, peritonitis, fistula,

Diverticulosis

Most patients with diverticulosis are asymptomatic, and diagnosis is often made as an incidental finding on colonoscopy or sigmoidoscopy (Hawkins et al, 2020; Bradshaw, 2023). Given that the disease is associated with ageing, the increase in incidence may be because human life expectancy has increased in recent years (Bradshaw, 2023). The availability of colonic imaging and cancer screening programmes has also enabled more diagnoses of diverticulosis (Rustom and Sharara, 2018).

Diverticular disease

The most commonly reported symptoms of diverticular disease include:

• altered bowel habit
• bloating
• abdominal pain (Strate and Morris, 2019)

Patients with irritable bowel syndrome can sometimes be misdiagnosed with symptomatic, uncomplicated diverticular disease, since the conditions both cause similar symptoms (Spiller, 2012).

One study looking at uncomplicated diverticular disease in randomly selected adults showed that many were very symptomatic; those over 60 years more were likely to report symptoms of:

• irritable bowel syndrome with abdominal pain
• diarrhoea

Diverticula occur most commonly in the sigmoid and descending colon, although 15% of diverticula are found in the ascending colon in ethnically Asian populations, where the incidence of right-sided diverticulitis is greater than on the left side. This difference in diverticula location across populations has been attributed to dietary and genetic factors. Diverticula can occasionally occur in the rectum, but these do not cause any symptoms (Hawkins et al, 2020).

People over the age of 65 years have a 65% likelihood of having diverticulosis, with some studies indicating that incidence rates increase exponentially with age. Up to 80% of people over 85 years have diverticulosis (Hawkins et al, 2020; Bretto et al, 2022). This increased incidence is thought to relate to changes in the mechanical features of the colonic wall with age – such as breakdown of collagen and an increase in luminal pressure, making herniation more likely to

Diagnosis of diverticular disease is confirmed on luminal imaging such as colonoscopy or sigmoidoscopy. Diverticulitis is often confirmed on investigations after patients present with symptoms. The most used diagnostic tools include:

• stool tests
• blood tests (particularly raised white cell count and inflammatory markers)
• endoscopy
• abdominal computed tomography (CT) imaging (Tursi, 2019)

Diverticular disease does not require any urgent treatment, as infection is not present in diverticula, most treatments focus on avoiding infection and progression to diverticulitis.

However, diverticulitis is a significantly more serious condition which requires treatment. The treatment plan is dependent on whether the condition is localised to the diverticula, or more advanced. Localised infection requires conservative management with intravenous fluids and antibiotics (NICE, 2019). In more severe cases, surgery may be required if complications are identified, such as an abscess, fistula formation or bowel obstruction (NICE, 2019).

Diverticular disease and diverticulitis are progressive in some patients, and multiple episodes can lead to the need for emergency surgery. Emergency bowel surgery has greater risks than elective surgery, because there is not always enough time to obtain up-to-date imaging or for pre-operative physical optimisation to be carried out (Lohsiriwat and Jitmungngan, 2019; Hawkins et al, 2020).