What is diverticulitis?

A diverticulum is an outpouching that forms in the lining of your digestive system, most commonly in the colon.  The presence of a diverticulum is known as diverticulosis and when it gets inflamed or infected, it is known as diverticulitis.

In the United States, acute diverticulitis is the third most common inpatient gastrointestinal diagnosis.  60% of the cases occurs in people aged above 60 years and it affects men and women equally.

What causes diverticulitis?

A diverticulum forms when the inner layers of the colon push through weak spots found in the outer muscular layer of the colon.  These weak spots are often where small arteries penetrate the muscular layer.  These outpouchings may get infected or inflamed when there is faeces stuck in it or when there is tearing of the layers due to stretching.

What are the risk factors for diverticulitis?

There are several factors which may increase your risk of developing diverticulitis and these include:

• Smoking
• Obesity
• Physical inactivity
• Ageing
• Low fibre diet
• Diet high in animal fat
• Drugs such as opioids, steroids and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
• Having a parent or sibling affected by the disease

What are the signs and symptoms of diverticulitis?

The signs and symptoms of diverticulitis depends on the location of the inflamed diverticulum, severity of the inflammation and presence of complications.  The signs and symptoms of diverticulitis include:

• Abdominal pain: the pain is most commonly located in the left side of the abdomen and is crampy in nature.
• Altered bowel habit: it can be in the form of constipation or diarrhoea.
• Nausea and vomiting.
• Fever
• Flatulence
• Bloating
• Absent bowel sounds: if there is perforation of the colon, your doctor may not hear any bowel sounds.
• Blood in stool.

Making a diagnosis

Diverticulitis may mimic many other diseases such as acute gastritis, acute pancreatitis, acute pyelonephritis, appendicitis, biliary disease, constipation, inflammatory bowel disease and larger bowel obstruction amongst others.  This is why your doctor will take a detailed history from you to know more about your symptoms.  After the history taking, your doctor will perform a thorough physical examination to look for signs of diverticulitis.  The history taking and abdominal examination often is sufficient to make the diagnosis of diverticulitis.  However when in doubt, your doctor may order some tests to confirm the diagnosis, such as:

• Blood tests: a complete blood count may indicate the presence of infection by showing an elevated white blood cell count.  Measurement of serum electrolytes is important in the case of diarrhoea and vomiting.  Liver function test may help to exclude other causes of abdominal pain.

• Pregnancy test: it is of utmost importance to rule out pregnancy in any women of childbearing age as certain antibiotics are to be avoided during pregnancy.
• Imaging studies: the best imaging method to confirm the diagnosis of diverticulitis is a computed tomography (CT) scan of the abdomen.  CT scan of the abdomen can assess the severity of the disease and detect presence of complications.  In addition, it is a much safer method than any imaging study involving contrast material.
• Barium enema: it is usually not the investigation of choice in the case of acute diverticulitis.  It should only be considered in mild to moderate cases of diverticulitis when the diagnosis is not certain.
• Abdominal x-ray: this test is mainly to rule out bowel perforation.
• Endoscopy: this test involves inserting a tube with a camera at its end into your anus to directly visualise the inside of your large intestine.  It is to be avoided during acute setting of the disease as it can worsen the disease or cause bowel perforation.  Once the disease has subsided, then only can colonoscopy be performed to evaluate the severity of the disease and rule out malignancy.

What are the treatments for diverticulitis?

The treatment of diverticulitis depends on whether it is a case of complicated or uncomplicated diverticulitis.  Uncomplicated diverticulitis is when there is no complication present while complicated diverticulitis is when there is the presence of complications.  The treatment of diverticulitis mainly involves medical and surgical care.

Medical care of diverticulitis

Uncomplicated diverticulitis can be managed outside of hospitals using oral antibiotics once a CT scan has been done to rule out any complications.  70-100% of people will be successfully treated.  The antibiotics used on an outpatient basis include ciprofloxacin, metronidazole and amoxicillin/clavulanic acid.  Your doctor will advise you to stick to a liquid only diet for the first few days.  Then, as your symptoms resolves, you can gradually advance the diet.

If there is presence of complications or severe diverticulitis, hospital admission will be required.  Your doctor will advise you not to eat and will prescribe you intravenous fluids.  Intravenous antibiotics will be initiated and examples include carbapenems, piperacillin/tazobactam, ampicillin/sulbactam, ticarcillin/clavulanic acid, metronidazole and ceftriaxone amongst others.  In addition, your doctor will prescribe pain killers to relieve your abdominal pain and an example is morphine.  NSAIDs, corticosteroids and aspirin are to be avoided as they can cause bowel perforation.  After 2-3 days of hospitalisation, your doctor will start you on a clear liquid diet and advance it as tolerated.  Furthermore, if you can tolerate intake of oral food, you will be placed on a 10-day course of antibiotics after which you may get discharged.

Surgical care of diverticulitis

People who fail non-operative management and present with signs of perforated bowel are treated with emergency surgery.  Usually the diseased segment of the bowel is removed and one end of the bowel is stitched closed while the other end is connected to the outside of your abdomen. This procedure is known as a colostomy.  Faeces will be collected in a bag called a colostomy bag or stoma bag.  After 3 months, you may be operated again to reverse the colostomy and the colon will be connected again to regain normal bowel function. However, this second surgical procedure is very challenging and is not suitable for everyone.  If the bowel is not inflamed, colostomy may be avoided and after removal of the diseased segment, the surgeon may connect the bowels together immediately.

What are the complications of diverticulitis?

If diverticulitis is left untreated several complications may ensue, these include:

• Bowel perforation.
• Obstruction of bowel.
• Abscess formation- this is a collection of pus in the pouch.
• Peritonitis- it is the inflammation of the abdominal cavity resulting from perforation of the bowel.  It is a medical emergency.
• Fistula formation- it is an abnormal connection between the bowel and other organs.

Prognosis

The prognosis depends on the severity of the disease, presence of complications and presence of any other coexisting medical conditions.  80-85% of people with diverticulitis remain asymptomatic.  Seeking medical advice early is key to prevent complications and improve prognosis.

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J. Alastair, I. and Simon, M., 2016. Davidson's Essentials of Medicine. 2nd ed. London: ELSEVIER.

Ghoulam, E., 2019. Diverticulitis Workup. 

Ghoulam, E., 2019. Diverticulitis Treatment and management.