Acute diverticulitis

What is a diverticulum – diverticulosis – diverticulitis of the colon?

The wall of the colon consists of several layers. The innermost layer is the mucous layer (mucosa) followed by the submucosal layer, then the muscular layer (the thickest part of the colon) and finally the fine serosa on the outside.

A diverticulum is a protrusion (herniation) of the mucosa and submucosa through the muscular layer, pushing out the serosa.

Diverticula can occur throughout the digestive system, from the oesophagus to the rectum. The most commonly affected segment is the sigmoid. The pressure in the colon is the highest in the sigmoid and causes the protrusion of the inner layers of the intestine through the muscular layer of the colon and causes diverticulosis.

One speaks of diverticulosis of the colon when multiple diverticula are present.

In patients living in Europe, diverticula are, greater in numbers, smaller in size and most frequently on the left side. In Asians, living in Asia, diverticula are usually on the right side, larger in size and smaller in numbers.

Age:

– 40 years: 10% population
– 80 years: 70% population

(Eng J Med 2007; 357:2057-2066)

Diverticulitis of the colon is the inflammation of the mucosal and submucosal sac protruding through the muscular wall of the colon.

+/- About 5% of patients with diverticulosis develop diverticulitis.

(American Gastroenterology Association 2015).

The cause of diverticulitis is not well understood. There are several hypotheses. The diverticulum is occluded by faecal debris, the trapped bacteria present in the diverticulum multiply, increasing the pressure in the diverticulum, which can lead to the development of inflammation of the wall. Low-fibre diet may also be a contributing factor to diverticulum inflammation, by singling out certain bacteria that can harm the intestinal wall.

Inflammation of diverticula can occur throughout the intestine. The colon and, in particular, the sigmoid are the most commonly affected.

• 80 – 85% of patients have no symptoms.
• Some patients will experience vague discomfort or discomfort in the lower abdomen and/or left flank.
• +/- 5-10% will develop diverticulitis.
• +/- 14/10000  a bleeding due to diverticulosis

Scand J Gastroenterol. 2019 Feb;54(2):205-209 Incidence of diverticular bleeding: a population-based study.Olafsson GD

• Low-noise symptoms. Discomfort in the left half of the lower abdomen (left fossa iliaca)
• Localised abdominal pain in the (left) lower abdomen or diffuse pain throughout the lower abdomen.
• Fever, chills
• Nausea and vomiting
• Bloating in the lower abdomen
• Diarrhea – constipation
• Air/gas present during urination (pneumaturia), is a sign of a connection between the diseased colon and bladder.

5 – 10% of patients with diverticulosis develop diverticulitis.

15% of patients with diverticulitis develop a complicated form of diverticulitis (abscess, peritonitis, obstruction…) .

Diverticular abscess

As a result of inflammation, the diverticulum may perforate, allowing faecal material and bacteria to seep into the abdominal cavity around the diverticulum.  An abscess will occur if the seeped faecal material and bacteria around the perforation, are contained by abdominal fatty tissue, abdominal wall and abdominal organs, (bowel, bladder, uterus or ovary) so that the bacteria do not infect the whole abdominal cavity.

Treatment

• A small abscess (< 3 cm) can be treated with antibiotics.
• A large abscess (> 3 cm) cannot always be treated with antibiotics and sometimes requires drainage of the abscess by percutaneous drainage by the department of radiology or surgical drainage if the abscess is inaccessible percutaneously.

If after perforation of an inflamed diverticulum, faecal material and bacteria around the perforation are not contained and flattened by surrounding organs and tissues, they can infect the entire abdominal cavity.

Peritonitis occurs when the peritoneum of the abdominal cavity becomes infected.

Treatment

• Peritonitis is a life-threatening situation. It requires emergency surgery.
• In most cases, the resection of the diseased segment of colon is necessary and the placement of a colostomy (stoma) is often unavoidable.

Treatment

• If symptoms of recurrent pain or bloating are present, resection of the sigmoid is suggested.
• These patients are at risk of an acute colon obstruction or perforation if elective surgery is not performed.

Treatment

If a sigmoid-bladder fistula is present, a resection of the sigmoid is suggested to prevent recurrent urinary tract infections

The risk of a second episode of acute diverticulitis: 11 – 35%

Risk factors:

• The severity of the first episode
• A complicated first episode of diverticulitis with abscess.
• The younger the patient at the first episode, the higher the risk of recurrence.

Après traitement d’un épisode de diverticulite aiguë , il est impératif de faire une coloscopie à froid 4 à 6 semaines après le traitement de la diverticulite afin d’exclure la présence d’une tumeur (si le patient n’a pas récemment subi une coloscopie).

4 – 6 weeks after treatment of an episode of acute diverticulitis, it is necessary to undergo a colonoscopy to rule out the presence of a tumor (if the patient has not had a colonoscopy recently).

• 2-4% of colonoscopies will demonstrate a tumor.
• 19% of colonoscopies will demonstrate polyps
• After an episode of complicated diverticulitis, 8-10% of colonoscopies will diagnose a cancer

(Ann surg 2017;265:954-959)
(Ann Surg 2014;259:263-272)

Does diverticulosis require surgery?

The presence of diverticulosis in the colon is not an indication that surgery is the only solution.

A mild episode of acute uncomplicated diverticulitis can be treated with analgesics without antibiotics and diet. In most cases, antibiotics and a light diet will be prescribed.

Neither medication nor a special diet can prevent an episode of diverticulitis. A high-fibre diet can reduce the risk of recurrence.

A severe diverticulitis with fever, tachycardia, diffuse abdominal pain

If intolerance to liquid or oral food.

• Failure of outpatient treatment (persistent fever or increased pain),
• Persistent high white blood cell count in blood sampling (after 2-3 days)
• Immune-compromised patient or patient with severe comorbidity
• Severe pain requiring intravenous analgesics

The indications for surgery have changed. Two episodes of diverticulitis or one episode of diverticulitis before the age of 40 are no longer indications for surgical intervention.

Current surgical indications

• Recurrent episodes of diverticulitis over a short period of time with significant morbidity for the patient.
• Chronic (persistent) diverticulitis, despite long-term treatment with antibiotics.
• Stenosis/obstruction of the colon after repetitive episodes of diverticulitis.
• Colo-vesical fistula.
• Abscess on diverticulitis that cannot be drained percutaneously, may require surgical drainage.
• Perforation of inflamed diverticulum with diffuse severe infection (peritonitis) of the entire abdominal cavity.

The first episode of acute diverticulitis is usually the most severe.

The risk of a colostomy during a new episode of diverticulitis after successful treatment of a first episode of acute diverticulitis: +/- 1/2000

Surgery involves removing the sigmoid/left colon affected by episodes of diverticulitis and reattaching the colon to the rectum.

See surgical procedure: Left colectomy / sigmoidectomy