Although most patients with diverticulosis do not have symptoms, approximately, 20 to 30 per cent will experience a single episode of diverticulitis. Approximately 80 per cent of patients affected are aged over 80. Diverticulitis occurs when one or more diverticula become inflamed. This is the main inflammatory complication of diverticular disease. Of these, 20 per cent will develop a significant complication such as an abscess, fistula or perforation. The inflammation may be confined to the diverticulum or extend through the layers into the adjacent organs. It is thought that bacteria or stool becomes stuck in the diverticulum, causing inflammation and pain on the left, lower side of your stomach.
- Abdominal pain
- Loss of appetite
- Diarrhoea or constipation
- Bleeding from your back passage
- Pain on passing urine (if the bladder is involved)
- Nausea and vomiting.
Blood tests may be abnormal or indicate inflammation.
In many cases the symptoms and signs mimic other intra-abdominal conditions (Crohn’s disease, pelvic inflammatory disease, ectopic pregnancy, cystitis, advanced bowel cancer), so imaging with scans is very important. Computed tomography (CT) is the diagnostic technique of choice because it so accurate. Generally, barium studies, colonoscopy or flexible sigmoidoscopy is avoided due to the risks of perforation (a tear or hole in the inflamed bowel wall).
- Mild diverticulitis: this can often be treated at home with painkillers such as paracetamol. Non-steroidal anti-inflammatory drugs such as ibuprofen are generally avoided because this can upset the stomach and increase the risk of bleeding. Your GP will prescribe a course of antibiotics that should be completed even if you feel better. Your GP may suggest that you have a liquid diet for a few days to help reduce the strain on the inflamed and infected colon.
- Severe or unresolving diverticulitis: this will require hospital admission. Management involves painkillers, plenty of fluids often through an intravenous drip, antibiotics and bowel rest (that is, nothing by mouth). In patients who have repeated episodes of diverticulitis, surgery may be advised to remove the affected part of the colon. This is because the risks of diverticulitis and its complications outweigh the risks of surgery.
Natural history of the development of diverticulitis
- All individuals with diverticulosis: 25 per cent develop diverticulitis after 10 years.
- Initial attack of diverticulitis: 80 per cent can be medically treated; 20 per cent develop complications during the initial attack.
- Diverticulitis treated medically: 33 per cent recurrence rate with 90 per cent occurring within 5 years.
- Recurrence of diverticulitis: 36 per cent of recurrences are associated with complications leading to surgery.
- The risk of recurrence: increases in patients aged less than 40 years or with three or more previous episodes.
If the inflamed diverticulum becomes infected this may lead to an abscess (pocket of pus-filled infection) forming in the abdominal cavity. If the abscess bursts then this can cause peritonitis. The presence of an abscess correlates with an increased risk of further attacks.
- Abdominal tenderness
- Sometimes shock may develop (pale, clammy and dizzy).
Abscesses can be picked up either on an ultrasound scan of the abdomen or with more detailed imaging such as a CT scan.
You will need treatment with antibiotics, intravenous fluids and sometimes a drain to remove the collection of infection. CT- or ultrasound-guided drainage can be successful in more than 90 per cent of cases and is particularly useful for abscesses larger than four centimetres. The technique used depends on local expertise, and may be used as a bridge to further definitive surgical resection once the patient is fitter.
Infected and inflamed diverticula can cause the surrounding tissue to become inflamed and stick together. This sometimes leads to formation of an abnormal connection (tunnel) between either the loops of bowel or from the bowel to another organ such as the bladder, skin or uterus. This abnormal connection is called a fistula and occurs in two per cent of cases with complicated diverticulitis.
Types of fistulas:
- Colovesical fistula: large bowel to bladder (65 per cent of cases)
- Colovaginal fistula: large bowel to vagina (25 per cent of cases)
- Coloenteric fistula: large bowel to small bowel
- Colouterine fistula: large bowel to uterus
- Colocutaneous fistula: large bowel to skin.
The symptoms largely depend on the type of fistula but colovesical fistulas are the most common. With this type of fistula you may have symptoms of bubbly urine, painful urination, irritative symptoms or blood in the urine. You will often pass air and stools from the large bowel to the connecting organ. In addition, you may experience a fever and abdominal tenderness
Various tests can be performed to diagnose a fistula including a barium enema, CT, magnetic resonance imaging (MRI) or endoscopy (camera test). One special test that can also be done is called a fistulogram. In this test, dye (contrast) is injected into the fistula via its opening on the surface; X-rays are then taken to determine the path of the fistula.
Antibiotics may play a role in the management of fistulas. Very few fistulas heal themselves, necessitating surgery in many cases. The exact type of surgery will depend on the type of fistula and where it has formed.
Bleeding (diverticular haemorrhage)
This is the most common cause of lower gastrointestinal bleeding in adults. A diverticulum sometimes contains a small blood vessel, which may bleed. This causes fresh bleeding from the rectum, which can vary in volume and is usually painless. Approximately three to five per cent of people with diverticulosis have a massive painless haemorrhage. In most cases the bleeding will stop spontaneously. Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to increase the risk of bleeding from diverticular disease, with over 50 per cent of patients with a bleeding diverticulum receiving NSAID treatment at the time of presentation.
Patients who have a severe bleeding may experience shock (that is, become pale or clammy, feel dizzy or even collapse if the blood pressure drops).
An endoscopy (flexible sigmoidoscopy or colonoscopy) to look at the colon is needed to identify the site of bleeding, confirm the cause and try to stop the bleeding using therapeutic modalities.
If the endoscopy is not successful in identifying the site of bleeding your doctor may arrange for you to have a CT angiogram. This is particularly useful if the rate of bleeding is more than 0.5 millilitres per minute. This test is performed by injecting a dye (contrast) into a vein. As contrast enters the bloodstream, it highlights blood vessels in white as the CT machine scans the stomach. This allows identification of the bleeding vessel followed by intervention such as selective embolisation if the rate of bleeding is greater than 0.5 millilitres per minute.
- Treatment is with intravenous fluids and, if you have become anaemic, a blood transfusion may be required.
- During the camera test, if the site of bleeding is identified, then it may be possible to stop the bleeding vessel using heat application, adrenaline injection or specialised clips to grasp the vessel.
- If CT angiography identifies the bleeding vessel it is possible that embolisation (which occludes the culprit blood vessel) or intra-arterial vasoconstrictor drugs can be administered. Intra-arterial vasoconstriction is the injection of a material that causes the blood vessel to narrow. CT angiography is performed by a specialist doctor known as an interventional radiologist in the angiography suite, or sometimes in the operating theatre. A small tube (catheter) is inserted through a small incision in the skin into a blood vessel. Using X-ray guidance and dye (contrast), the catheter is manoeuvred towards the bleeding vessel. Material is then injected at the treatment site to block the vessel or cause it to narrow. X-rays are taken afterwards to ensure that the targeted vessel has stopped bleeding. The catheter is removed and pressure is applied to the area where the catheter was introduced. Stitches are not needed and you will require up to six hours of bed rest after the procedure. A sedative or general anaesthetic is normally given for this procedure.
- If the bleeding is severe and persistent, then rarely surgery may be required to control the bleeding and remove the bleeding diverticulum.
Perforation and peritonitis
One to two per cent of urgent cases result in an infected diverticulum bursting, leading to a free perforation. This can lead to a serious infection spreading into the abdominal cavity (peritoneum) and lining of the abdomen. This is called peritonitis and is life threatening.
- Severe abdominal pain
- Nausea and vomiting
- A swollen and bloated stomach
- Fever and chills
A plain abdominal X-ray may show free air in the abdomen. This is confirmed by a CT scan of your abdomen to look for free air, and a blood test will show raised markers of inflammation and infection. Barium studies and endoscopy are contraindicated.
Treatment is required immediately with strong antibiotics and fluids via an intravenous drip, resting the bowel (that is, nothing by mouth), painkillers and, often, emergency surgery. A urinary catheter (tube) may be placed into your bladder to ensure that you are passing enough urine (a marker of kidney function and hydration).
A stricture is a narrowing of the bowel. There are two types of strictures: inflammatory and non-inflammatory.
Inflammatory stricture: in acute diverticulitis the inflammation may cause a transient narrowing, which resolves once the inflammation settles down.
Non-inflammatory stricture: over a period of time, after recurrent acute episodes, the inflamed diverticula can cause permanent scarring of the colon resulting in a narrowing. This can lead to symptoms of subacute bowel obstruction which may be followed by a complete obstruction.
- Abdominal pain mainly after meals
- Abdominal distension
- Difficulty with evacuation of stool and wind.
- Balloon dilatation: a balloon can be placed in the area of the stricture and inflated to stretch the narrowing. This may be performed in mild and short strictures, which are certain not to be cancerous. This type of procedure is done under sedation using an endoscope to access the bowel.
- Stenting: a tube can be placed in the area of the stricture and opened up to relieve the narrowing. This can be done to decompress the bowel and used as an interim measure until surgery can be performed. It may also be performed in those who are not fit for surgery, but require alleviation of symptoms. This is a standard technique in cancerous strictures but may be associated with complications in benign disease unless surgery is performed subsequently.
- Surgery: the affected stricture is removed (resected). This is often performed in complete bowel obstruction or where a cancerous stricture cannot be excluded.
Bowel obstruction can occur secondary to abscess formation or oedema or from stricture formation after recurrent attacks of diverticulitis. Strictures can either cause complete or partial blockage of the bowel.
Complete blockage of the bowel
This is an emergency and requires immediate treatment because, without treatment, the bowel becomes more distended as air builds up within it. As a result the bowel begins to break down and can burst, leading to peritonitis. Patients with complete obstruction experience cramp-like pain, anorexia, nausea, inability to pass wind or stools, and a swollen, distended stomach. The diagnosis is often made either by a plain abdominal X-ray to look for dilated bowel loops and an erect chest X-ray to look for free air under the diaphragm, or by a CT scan of the abdomen.
This involves bowel rest (that is, nothing to eat), a drip and surgery to remove the stricture and affected bowel. The amount of bowel removed and type of surgery will depend of the extent and severity of disease. Often a small tube called a nasogastric (NG) tube is passed through the nose, down the oesophagus (food pipe) and directly into the stomach. This provides relief from the build-up of pressure in the stomach and helps remove fluid and gas – thereby easing symptoms. A urinary catheter (tube) may be placed into your bladder to ensure that you are passing enough urine (a marker of kidney function and hydration).
This is less of an emergency but nevertheless requires conservative treatment with bowel rest and intravenous fluids (drip into a vein). If it fails to resolve on its own then surgery may be needed.
When will I have to be admitted to hospital?
- If an acute attack of diverticulitis treated at home does not settle within 48 to 72 hours
- If you are unable to keep down tablets (painkillers and antibiotics) or fluids
- If the pain is not being controlled with oral medication
- If you develop symptoms indicating a serious complication, that is abscess, fistula, perforation or peritonitis
- If you have severe or constant bleeding or if you require a blood transfusion
- If are frail and have multiple medical problems that mean recovery is likely to be more difficult to achieve at home.