Introduction

Diverticula are pouches in the lining of the intestine. They arise when the wall of the intestine bulges out through weak areas of intestinal muscle. The pouches are usually small and balloon-like, and the contents of the bowel (stool, or “poop”) might get into them. Although diverticula are often harmless, they may lead to bowel problems and cause pain. Simply put, there are three different conditions:

• Diverticulosis: The lining of the intestine bulges out in a number of places, but this doesn’t cause any symptoms or problems.
• Diverticular disease: The bulging pouches cause symptoms or lead to problems (complications).
• Diverticulitis: The pouches are inflamed or infected.

Diverticula can cause recurring or permanent symptoms. This is referred to as chronic diverticular disease. Diverticulitis can usually be treated effectively, but may have serious consequences if the inflammation spreads.

Diverticula and diverticulitis

Symptoms

Most diverticula don’t cause any symptoms. Diverticular disease is typically associated with pain in the lower left side of the abdomen (tummy) or – less commonly – the right side. It can also lead to bloating, constipation or diarrhea. The symptoms often go away for a while, but may be constant. They commonly get worse after meals, and then better again after going to the toilet and having a bowel movement. Sometimes diverticula lead to bleeding too.

If they become inflamed (diverticulitis), they cause sudden dull pain in the abdomen, accompanied by a mild fever. Other symptoms include constipation, diarrhea, bloating, nausea and sometimes cramping too. Diverticulitis rarely leads to vomiting. If a doctor applies pressure to the abdomen, the tummy muscles automatically tense up (a reflex known as muscular defense). If they suddenly let go, the pain gets worse.

Causes and risk factors

Diverticula form in weak areas of the intestinal muscles. They usually arise in the sigmoid colon. This s-shaped section of the large intestine is roughly 40 to 45 centimeter long and found just in front of the rectum. The contents of the intestine put the most pressure on the muscular wall here.

Some people are more likely to develop diverticula because of their genes. Further risk factors include weak connective tissue and problems with the wave-like movements of the intestinal wall. Older and very overweight people are at greater risk, too.

The influence of lifestyle factors hasn’t yet been properly determined. A diet that is low in fiber can lead to constipation and hard stools, so it seems logical that too little fiber should increase the risk of diverticular disease. Eating a lot of red meat, smoking and not getting enough movement are also believed to be risk factors.

It’s still not clear how diverticula become inflamed and what increases the risk of this happening. But inflammation is believed to be more likely in areas of reduced blood supply and if hard lumps of stool form in the diverticula.

Complications are more common in people who have a weakened immune system (for instance, after an organ transplant) or severe kidney disease. The long-term use of particular medications probably increases the risk of more serious complications. These medications include non-steroidal anti-inflammatory drugs (NSAIDs), steroids, acetylsalicylic acid (the drug in medicines like Aspirin) and opiates.

Prevalence

Many people have diverticula without knowing it. They are more common in older age: About 10% of people under the age of 50 have diverticula, and about 50% of people over the age of 70 have them. They are equally common in men and women.

About 1% of all people who have diverticula develop diverticulitis within ten years. This inflammation can occur at any age.

Effects

Diverticula often remain unnoticed if they don’t cause any symptoms. But they sometimes lead to chronic digestive problems and pain, or may even become inflamed or infected.

Diverticulitis can usually be treated effectively and then goes away after a few weeks. But about 20% of those affected get diverticulitis again within a few years.

Diverticulitis can lead to complications if the inflammation spreads to the wall of the intestine, surrounding tissue or nearby organs. Abscesses (collections of pus) or fistulas may develop. A fistula is an unnatural tunnel-like passageway between two organs, for instance between the intestine and the bladder.

One rare but serious complication may arise if the wall of the intestine tears (intestinal perforation). If the contents of the intestine then leak out into the abdominal cavity, the inner lining of the tummy (peritoneum) may become inflamed, leading to a life-threatening condition known as peritonitis. This typically causes severe tummy pain, a hard abdominal wall, fever, nausea, a rapid heartbeat and general weakness. It is important to recognize these peritonitis symptoms and quickly seek medical help.

In some people, diverticula keep becoming inflamed despite having been treated successfully in the past. This can lead to scarring that causes the intestine to become narrow (stenosis), making it difficult for stool to pass through it. In extreme cases, the intestine becomes blocked (ileus). Some people have constant diverticula symptoms although their intestine isn’t inflamed. The risk of complications is greatest when someone has diverticulitis for the first time. After that, recurring inflammations are a lot less likely to lead to complications. The main consequences of recurring diverticulitis are chronic symptoms such as irregular bowel movements, bloating and abdominal pain.

It’s good to know that diverticula do not develop into bowel cancer. This kind of cancer develops from polyps in the bowel.

Diagnosis

If you go to see a doctor about your symptoms, they will ask you about various things, such as your medical history and whether you are taking medication. This is followed by a physical examination where they listen to your tummy, and also feel your tummy and rectum. Depending on the symptoms, you may have blood and urine tests, and your temperature might be measured.  You will usually have an ultrasound scan as well. If there is still no clear diagnosis, you may need to have a CT (computed tomography) scan and perhaps a colonoscopy too (inspection of the inside of the intestine using a camera).

This can help to rule out other illnesses – the symptoms of diverticular disease are similar to the symptoms of conditions like appendicitis or irritable bowel syndrome (IBS).

Colonoscopies are too risky during acute diverticulitis. But people are often advised to have a colonoscopy about 4 to 6 weeks after the symptoms have cleared up. This is to make sure that they weren’t caused by polyps, bowel cancer or another illness.

Prevention

Eating enough fiber helps to make sure that your stool doesn’t get too hard. So it would seem logical that fiber should prevent pain and inflammation in people with diverticula. There’s a lot of fiber in whole-grain foods, vegetables, legumes (e.g. beans, lentils) and fruits. Physical exercise stimulates digestion too, but it isn’t clear whether it can prevent the symptoms.

Sometimes people are advised to avoid certain foods – particularly nuts, grains, sweetcorn and popcorn. For a long time it was thought that fragments of these foods could get stuck in the diverticula and cause diverticulitis. But studies have shown that not to be true. So you don’t have to avoid eating nuts, for example.

Treatment

Diverticula that don’t cause any symptoms don’t have to be treated. The treatment options for diverticulitis depend on how severe it is.

The aim of treatment is to

• avoid potential complications and relieve acute symptoms,
• prevent it from coming back, and
• relieve chronic symptoms.

Diverticulitis inflammations are caused by a bacterial infection, so they can be treated with antibiotics. But people usually only need to use antibiotics if complications arise or if there’s an increased risk of them arising. Complications may have to be treated in hospital.

If acute diverticulitis doesn’t improve or someone has constant symptoms, the affected part of the large intestine can be surgically removed. Because of the associated risks, it’s important to carefully consider the pros and cons of surgery first. Serious complications such as peritonitis require immediate surgery, though.

For people who have chronic symptoms, it might be worth trying to eat more fiber. There’s not yet enough good research to be able to say whether probiotic food products can help.

Nowadays there’s good reason to believe that antibiotics and surgery often aren’t as necessary as previously thought.

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.

Sources

• Andeweg CS, Berg R, Staal JB, ten Broek RP, van Goor H. Patient-reported Outcomes After Conservative or Surgical Management of Recurrent and Chronic Complaints of Diverticulitis: Systematic Review and Meta-analysis. Clin Gastroenterol Hepatol 2016; 14(2): 183-190. [PubMed: 26305068]
• Carabotti M, Annibale B, Severi C, Lahner E. Role of Fiber in Symptomatic Uncomplicated Diverticular Disease: A Systematic Review. Nutrients 2017; 9(2): pii: E161. [PMC free article: PMC5331592] [PubMed: 28230737]
• Lahner E, Bellisario C, Hassan C, Zullo A, Esposito G, Annibale B. Probiotics in the Treatment of Diverticular Disease. A Systematic Review. J Gastrointestin Liver Dis 2016; 25(1): 79-86. [PubMed: 27014757]
• Leifeld L, Germer CT, Böhm S, Dumoulin FL, Häuser W, Kreis M et al. S2k-Leitlinie Divertikelkrankheit/Divertikulitis. Z Gastroenterol 2014; 52(7): 663-710. [PubMed: 25026009]
• Morris AM, Regenbogen SE, Hardiman KM, Hendren S. Sigmoid diverticulitis: a systematic review. JAMA 2014; 311(3): 287-297. [PubMed: 24430321]

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