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What is diverticular disease?
It is an acquired condition, in which there are small out-pouchings of the mucosa of the large intestine, known as diverticulae.
  • Diverticulosis – the presence of diverticulae in the large intestine
  • Diverticular Disease – the presence of symptoms resulting from the existence of diverticulae in the large intestine
  • (Acute) diverticulitis – ongoing inflammation of one or more diverticulae


  • Primarily a disease of the elderly, very uncommon in those under 40
  • 50% of the over 70’s have diverticulae
  • Most commonly occurs in the sigmoid colon
  • 75-90% of cases of diverticulosis are asymptomatic
  • Diverticular disease is present in 10-25% of cases, and of these, about 20% will develop acute diverticulitis at some stage.
  • Slightly more common in females
  • Associated with a western lifestyle


  • Lack of fibre in the diet (particularly in processed foods)


It is thought that in the presence of a lack of fibre, the muscles of the colon must work harder to move faeces along. This causes very high pressures in the colon, and as a result, some parts of the mucosa will form out-pouchings.
  • This can occur, because the muscle coverage along the outside of the colon (the taeniae coli) do not entirely encircle the whole of the intestine, but instead are present in bands. The herniation of the mucosa occurs inbetween these bands.
  • There may also be muscle changes, whereby the taeniae coli become thickened and fibrosed, pre-disposing the formation of diverticulae

Clinical features

  • Up to 95% symptomless
  • Diverticular disease can cause erratic bowel habits (constipation or diarrhoea) and left iliac fossa pain, which may or may not be colicky

Complications of diverticular disease:

  • Acute diverticulitis
    • Left iliac fossa pain
    • Malaise / fever
    • Palpable mass
    • Abdominal distension
    • Tachycardia
    • These symptoms are similar to appendicitis, but usually occur on the left hand side.
    • This inflammation will often spontaneously resolve, but in some cases it can progress to:
      • Fistulation
      • Abscess
      • Peritonitis
      • Perforation
      • Haemorrhage
      • In some cases, acute diverticulitis can be life threatening (e.g. in cases of perforation)
  • Perforation
  • Large bowel obstruction
  • Fistula (to bladder)
  • Fistula to small intestine
  • Lower GI bleed


  • Clinical Examination – the sigmoid colon may be palpable
  • Barium Enema – the investigation of choice, but should not be used if there are active complications.
  • Ultrasound – can asses bowel wall thickness, and rule out other differentials
  • Sigmoidoscopy – if other investigations have been inconclusive
  • Diverticular disease is notorious for concealing colon carcinoma

Investigations for Acute Diverticulitis

  • CRP and ESR – usually raised
  • Ultrasound / CT – can show wall thickening, diverticulae, and also abscess or perforation

Treatment for Acute Diverticulitis

  • Antibiotics (usually metronidazole)
  • Fluids
  • Analgesiabut be careful! You don’t want to give a constipating analgesic (i.e. many opioids, particularly morphine) as this also raises intra-luminal pressure
Often patients can be managed at home, but in severe cases, hospitalisation may be required, in which case fluids may be given IV

Long term management of Diverticular Disease

  • Asymptomatic disease – no direct treatment – recommend high fibre diet and high fluid intake
  • Symptomatic disease –
    • Analgesics – again, avoid opioids
    • Laxatives, if necessary – but avoid stimulant laxatives
    • Anticholinergicsmay be useful in patients with over-active sigmoid colon
    • Surgery – to resect the sigmoid colon – in severe cases

More Information

Diverticulae are acquired defects, and they are most common in the descending colon and sigmoid colon of elderly people.


  • Diverticulae are present in 50% of over 70’s.
  • In 75-90% of cases they are asymptomatic, and this form of the disease is called diverticulosis. It is usually discovered incidentally on barium enema.
  • In cases where there are symptoms, we call this diverticular disease and these cases account for 10-25%of all cases of diverticulosis.
  • Diverticulitis is present when the diverticulae becomes inflamed. Thus, all patients with diverticulitis have diverticular disease, but not all patients with diverticular disease have diverticulitis.
  • More common in females
  • Associated with a western lifestyle. It is very rare in China, India and Africa.
  • Uncommon before the age of 40
  • About 20% of patients with diverticulosis will develop acute diverticulitis.


  • Life-long low fibre diet.
  • The condition is rare in populations with a high fibre diet (e.g. in Asia). In these places the disease is actually more common in the right colon (ascending), and its pathology is thought to be different.
  • Refined foods are notorious for being a pre-determining factor.


The exact pathology is not known. It is thought that the high pressures needed to force faeces along the colon in the absence of fibre leads to herniation of the mucosa between the teniae coli. This herniation occurs mainly alongside blood vessels. Many people believe that the increased pressure may be due to changes in the longitudinal muscles of the colon. Often these muscles become thickened and are more likely to spasm, and thus the incidence of high pressure in the colon is likely to increase.
Classically the colonic mucosa will be pleated, due to a shortening of the colon (particularly sigmoid colon) due to the muscle changes described above. The lumen will become narrowed due to the pleated mucosa and hypertrophied muscle.
Diverticulae occur more commonly between the mesenteric and anti-mesenteric taeniae.
Taeniae Coli – these are the bands of longitudinal muscle that stretch the length of the large intestine. They are unusual, because in the rest of the GI Tract, the longitudinal muscle completely encircles the lumen, but in the large intestine, it only runs in three bands, leaving much of the mucosa with the ‘support’ behind it.
The diverticulae themselves consist of mucosa covered by a layer of peritoneum. They have a thin neck, but a large pouch, so that things may become lodged in them. Often there is an artery, or sometimes a vein right next to the neck.
They are likely to become inflamed if something gets stuck in them (e.g. faeces, a nut, popcorn); the most common thing being hard, compacted faeces. Behind this faeces ‘plug’ bacteria are trapped and allowed to proliferate. When they become inflamed, this is acute diverticulitis.
This inflammation will often spontaneously resolve, but in some cases it can progress to:
  • Fistulation
  • Abscess
  • Peritonitis
  • Perforation
  • Haemorrhage
Repeated episodes of inflammation, even if they do not progress, will often cause further problems. Repeated inflammation will causes a fibrosis and further thickening of the bowel wall, which will narrow the lumen, and eventually lead to total obstruction.
Classically the disease will be on the left side of the colon, and will be characterized by inflammation and perforation.
Rarer Varieties of Diverticular Disease
There appears to be another type of diverticular disease that equally affects the whole colon, and this is not associated with muscle changes. In this disease there may be underlying connective tissue defects that allow mucosal herniation. Bleeding is the most common complication with these type of patients. This type of diverticular disease can occur at any age.
The diverticular disease that occurs in the Asian population seems to occur entirely on the right side of the colon, and its causatory factors have yet to be determined, although it is probably related to diet.

Clinical features

  • Up to 95% of patients are symptomless
  • In those with symptoms there are often erratic bowel habits and left iliac fossa pain. The pain maybe like an ache or it might be colicky. Constipation is more common that diarrhoea, but one or the other is often present.
  • Often diverticulae are discovered incidentally whilst doing a barium enema for colon cancer.
  • Up to 30% of those with symptoms will develop complications, which can include:
    • Acute diverticulitis
      • Left iliac fossa pain
      • Malaise / fever
      • Palpable mass
      • Abdominal distension
      • Tachycardia
      • These symptoms are similar to appendicitis, but usually occur on the left hand side.
    • Perforation
      • Peritonitis
      • + all the symptoms above
    • Large bowel obstruction
      • Absolute constipation
      • Colicky bowel pain
      • Vomiting
    • Fistula (to bladder)
      • Cystitis
      • Pneumaturia
      • Recurrent UTI’s
      • Faecal matter in urine (often faecal discharge from vagina)
    • Fistula to small intestine
      • Diarrhoea
    • Lower GI bleed
      • Spontaneous and painless. Try to distinguish from angiodysplasia.

General Investigations

  • Clinical examination – the sigmoid colon is often palpable, and it can also often be felt on PR exam.
  • Barium enema – this is the usual method of diagnosis, but should not be used in patients with complications. You should make sure you use a water soluble contrast if ‘barium’ is not the exact contrast used. It will enable you to see areas of colonic spasm and multiple diverticulae. Sometimes the diverticulae extend right into the rectum, but this is rare.
Often, bowel emptying before one of these investigations is carried out is not sufficient, and as a result, small blobs appear on the image, that may cause concern as being cancerous.
The main two signs that will confirm diverticular disease are colonic narrowing in an area of diverticulae. This however in no way rules out the possibility of a co-existing malignancy.
  • Abdominal ultrasound – this assesses wall thickness and excludes paracolic inflammatory bowel disease.
  • Sigmoidoscopy – sometimes used if it has been difficult to obtain a clear image from other imaging methods.
  • Diverticular disease is notorious for concealing colon carcinoma. Sigmoidoscopy/colonoscopy is the one investigation that can clearly say there is no carcinoma present.
    • If colonic bleeding is present, this strongly suggests the existence of polyps or carcinoma

Investigations for Acute Diverticulitis

  • Blood tests – the CRP and ESR (erythrocyte sedimentation rate) are often raised.
  • Imaging – a USS is usually quite accurate, and can detect perforation, free liquid and collections. It is usually more readily available and is much cheaper than CT. A CT is quite commonly used these days and can be more accurate in severe disease. It can show wall thickening and diverticulae as well as perforations and abscesses.
    • There is usually a streaky increased density seen in the pericolic fat on a CT scan. This is one of the factors that helps distinguish the disease from colonic malignancy.
  • You should not perform a colonoscopy or contrast scan if you think it is an acute attack / there are complications.

Treatment for acute attack

Often this can be treated at home, with antibiotics and plenty of fluids. If the patient is in particularly severe pain, or they cannot take oral fluids then they may require hospitalization and IV fluids with stronger pain relief. If it is particularly sever the patient needs to be nil by mouth.
  • Antibiotics- metronidazole – 400mg /8h or cefuroxime.
  • Analgesia – make sure you don’t give one that can cause constipation and make sure you don’t give morphine as it increases intraluminal pressure in the colon.
The symptoms should start to die down within 48 hours. If they don’t then you should consider barium enema or colonoscopy 3 weeks later.
About 1/5 of acute presentation patients require operating on after their first visit to hospital.
Patients who have an initial uncomplicated attack of diverticulitis that clears up have a 70% chance of never having an acute attack again.

Management after diagnosis of diverticular disease

  • Diverticulitis that is asymptomatic and discovered incidentally requires no treatment – although you may want to recommend high fibre diet and plenty of fluids
  • There is no evidence to suggest increasing dietary fibre reduces the development of further diverticulae or reduces the risk of complications. However it may reduce the symptoms as it adds bulk to the faeces and makes them easier to pass. This will reduce transit time, and colonic pressure. It is recommended that patient eat 20-30g of bran per day. Rough fibre is better than fine fibre. A diet high in fibre is often un-palatable and so bulk forming agents may be given as supplements. It is also important that patients increase their fluid intake.
  • Stimulant laxatives should be avoided
  • Analgesics may be given, but you must make sure they are non-constipating. Morphine should never be given, as it increases intraluminal pressure.
  • Anticholinerics are often given, but they have not been proven to help. They are given because they reduce colonic motility, and some patients have hypermotility of the sigmoid colon.
  • Surgery – If pain is severe or unresponsive then it is possible to resect the sigmoid colon. Ideally this should take place 8 weeks after the most recent attack of diverticulitis. Only the segment affected by the inflammation needs to be removed – not the whole area containing diverticulae. In general this will involve all of the sigmoid colon and part of the retrosigmoid colon. A colorectal anastomosis is usually possible and the surgery can usually be performed laparoscopically.
    • A common type of surgery is Hartmann’s procedure. It is often used to treat complications of diverticulitis – mostly fistula formation (in the case of an abscess percutaneous drainage is often preferred these days. In this procedure, a segment of the colon is removed, but an anastomosis is not created straight away. This is because the idea of this surgery is to avoid making an anastomosis in the presence of severe faecal contamination / gross sepsis. Instead the patient will have to live with a stoma for 4-6 months, before an anastomosis is created subsequent surgery.


  • Fibrosis – this often occurs after incidents of acute diverticulitis have resolved themselves
  • Perforations – this can be self contained in the form of an abscess or it can totally perforate and cause peritonitis. It usually, but not always, occurs during an acute attack of diverticulitis. Surgery is usually required. The presence of an abscess is usually indicated by a mass, and the diagnosis can be confirmed by ultrasound or CT. It is thought that the abscess is caused by a combination of two factors
    • A pericolic abscess must be drained. Usually this will be done 6 weeks after the initial attack. A drain is put in, and washed out with saline to keep it patent. Once no more pus is coming from the drain, a sinograhpy may be performed to check if it is fully drained. It can take a couple of weeks for it to drain.
  • Ruptured Abscess – it is thought this results from the occlusion of blood vessels at the neck of the diverticulum, and as a result a loss of blood supply to the mucosa forming the wall of the diverticulum. this is very similar to the way a gangrenous ruptured appendix will form. Don’t forget that behind the ‘plug’ in the neck of the diverticulum, bacteria are allowed to proliferate. It will present with:
    • Generalised abdominal pain, often also referred to the right shoulder tip, from extensive pneumoperitoneum.
    • Fever and circulatory collapse – signs of sepsis.
    • Abdominal tenderness and rigidity.
    • This complication is a surgical emergency.
  • Obstruction – this often occurs after repeated episodes of diverticulitis.
  • Hemorrhage – often you will find slight iron-deficiency aneamia in patients with mild disease. This is easily treatable with iron supplements, and its cause is actually unknown. Far rarer is massive haemorrhage. This is thought to be caused by rupture of a blood vessel in the neck of one of the diverticulae. It will present with a large amount of blood in the stool – the stool is often maroon coloured. This can be life threatening, particularly in elderly patients. It is often difficult to locate the site of the haemorrhage, especially in those with widespread disease. In 70% of cases this bleeding will stop by itself, and then the location can later be confirmed by colonoscopy, or sometimes angiography (x-ray after insertion of a contrast agent). If it is life-threatening, emergency re-section may be needed.
    • In patients who have a small amount of bleeding regularly, the cause is unlikely to be diverticular disease.

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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