What is diverticulitis?
What causes diverticulitis?
Doctors aren't sure what causes diverticula in the colon (diverticulosis). But they think that a low-fibre diet may play a role. Without fibre to add bulk to the stool, the colon has to work harder than normal to push the stool forward. The pressure from this may cause pouches to form in weak spots along the colon.
Doctors aren't sure what causes diverticulitis. Bacteria grow in the pouches, and this can lead to inflammation or infection.
What are the symptoms?
Symptoms of diverticulitis may last from a few hours to a week or more. Symptoms include:
- Belly pain, usually in the lower left side, that is sometimes worse when you move. This is the most common symptom.
- Fever and chills.
- Bloating and gas.
- Diarrhea or constipation.
- Nausea and sometimes vomiting.
- Not feeling like eating.
How is diverticulitis diagnosed?
Your doctor will ask about your symptoms and will examine you. He or she may do tests to see if you have an infection or to make sure that you don't have other problems. Tests may include:
How is it treated?
The treatment you need depends on how bad your symptoms are. You may need to have only liquids at first, and then return to solid food when you start feeling better. Your doctor will give you medicines for pain and antibiotics. Take the antibiotics as directed. Do not stop taking them just because you feel better.
For mild cramps and belly pain:
- Use a heating pad, set on low, on your belly.
- Relax. For example, try meditation or slow, deep breathing in a quiet room.
- Take medicine, such as acetaminophen (Tylenol, for example). Be safe with medicines. Read and follow all instructions on the label.
You may need surgery only if diverticulitis doesn't get better with other treatment, or if you have problems such as long-lasting (chronic) pain, a bowel obstruction, a fistula, or a pocket of infection (abscess).
How can you prevent diverticulitis?
You may be able to prevent diverticulitis if you drink plenty of water, get regular exercise, and eat a high-fibre diet. A high-fibre diet includes whole grains, fresh fruits, and vegetables.
Doctors aren't sure what causes diverticulitis. Bacteria grow in the pouches (diverticula), and this can lead to inflammation or infection. Pressure may lead to a small perforation or tear in the wall of the intestine. Peritonitis, an infection of the lining of the abdominal wall, may develop if infection spills into the abdominal (peritoneal) cavity.
The reason diverticula form in the wall of the large intestine (colon) is not completely understood. Doctors think diverticula form when high pressure inside the colon pushes against weak spots in the colon wall. Uncoordinated movements of the colon can also contribute to the development of diverticula.
Normally, a diet with adequate fibre (also called roughage) produces stool that is bulky and can move easily through the colon. If a diet is low in fibre, the colon must exert more pressure than usual to move small, hard stool. A low-fibre diet also can increase the time stool remains in the bowel. This adds to the high pressure. Pouches may form when the high pressure pushes against weak spots in the colon where blood vessels pass through the muscle layer of the bowel wall to supply blood to the inner wall.
It is not known why some people who have these diverticula (a condition called diverticulosis) develop diverticulitis and others do not.
Symptoms of diverticulitis may last from a few hours to several days. These symptoms may include:
- Tenderness, cramps, or pain in the abdomen (usually in the lower left side but may occur on the right) that is sometimes worse when you move.
- Fever and chills.
- A bloated feeling, abdominal swelling, or gas.
- Diarrhea or constipation.
- Nausea and sometimes vomiting.
- Loss of appetite.
Complications also can cause symptoms. If an abnormal opening (fistula) develops between the colon and the vagina or the colon and the urethra, you may pass air or stool from the vagina or the urethra.
Diverticulitis occurs when pouches (diverticula) that have developed in the wall of the large intestine (colon) become inflamed or infected. It is not clearly understood why 20 out of 100 people who have these pouches—a condition called diverticulosis—develop diverticulitis and the others do not.
In Western countries (North America and Europe), diverticulitis usually affects the left side of the colon (sigmoid colon).
Mild attacks of diverticulitis, with few symptoms or signs of infection or inflammation, sometimes heal without treatment. In most cases, a doctor recommends oral antibiotics to resolve an infection and a clear liquid diet to rest the bowel until inflammation goes away.
When infection and symptoms are severe, diverticulitis is treated in the hospital. Treatment includes antibiotics given in a vein (intravenous, or IV) and resting the bowel with IV fluids. If severe diverticulitis is not treated, complications such as an abscess or fistula may develop. Surgery often is needed to treat complications.
It is common to have lower abdominal pain after recovering from an attack of diverticulitis. But this pain is not always a return of diverticulitis. Less than half of people ever have a second diverticulitis attack. Of those who do have another attack, about half have the second attack within 1 year of their first one.footnote 1
What Increases Your Risk
The possibility of having diverticulitis increases with age.
You may be more likely to develop diverticulitis if you:
When should you call your doctor?
Call 911 or other emergency services immediately if the person has been bleeding from the anus and has signs of shock, which could mean that a diverticular pouch is bleeding (diverticular bleeding). Signs of shock include passing out or feeling very dizzy or light-headed.
Call your doctor immediately if you have pain in the abdomen that is in one spot (as opposed to general pain in the abdomen), especially if you also have:
- Fever or chills.
- Nausea and vomiting.
- Unusual changes in your bowel movements or abdominal swelling.
- Blood in your stool.
- Pain that is worse when you move.
- Burning pain when you urinate.
- Abnormal vaginal discharge.
Call your doctor immediately if you have:
- Severe pain in the abdomen that is getting worse.
- Pain in the abdomen that becomes worse when you move or cough.
- A stool that is mostly blood (more than a few streaks of blood on the stool). Blood in the stool may appear as reddish or maroon-coloured liquid or clots or may produce a black stool that looks like tar.
- Passed gas or stool from your urethra while urinating. This likely means that you have an opening (fistula) between the bowel and the urinary tract.
Call your doctor if you:
- Have cramping pain that does not get better when you have a bowel movement or pass gas.
- Have rectal bleeding, a change in bowel habits, and you have been losing weight without trying.
Call your doctor if you are treating mild diverticulitis at home and:
- You have a fever.
- Your pain is getting worse.
- You can't keep down liquids.
- You are not better after 3 days.
It is not uncommon to have bloating, gas pressure, or mild abdominal (belly) pain. These can be caused by eating certain foods or by stress. Home treatment usually will take care of these symptoms. If home treatment does not help or if the symptoms become worse, see your doctor.
Who to see
Your family doctor or general practitioner can diagnose and treat diverticulitis.
If further tests are needed, if your symptoms do not respond to treatment, or if you may need surgery, your doctor may refer you to a:
Examinations and Tests
Your doctor will take a history and do a physical examination if diverticulitis is suspected. Depending on your symptoms, you may have one or more tests to rule out other medical problems that could be causing your symptoms. The extent of testing will depend on how bad your symptoms are and how long they have lasted.
These tests may be done any time you see your doctor about abdominal pain or other symptoms.
- Complete blood count (CBC) may show if you have an infection or if you have too few red blood cells in your blood, possibly because of bleeding in the colon.
- Urinalysis may show you have a urinary tract infection.
- Abdominal X-ray may provide clues about the cause of abdominal pain and other symptoms.
- The digital rectal examination looks for tenderness or a mass in the lower pelvic area.
- The faecal occult blood test looks for blood in your stool.
Tests done as needed
Depending on your symptoms, your doctor may want to do one or more of these tests.
- A computed tomography (CT) scan may be done if symptoms suggest you have a pocket of infection (abscess) in your abdomen or that a pouch (diverticulum) has burst. The scan also can reveal other possible causes of your symptoms.
- A barium enema X-ray may be used to show diverticula or other possible causes of your symptoms. But a barium enema X-ray usually is not done while you are having an attack of diverticulitis because of the risk that the barium might spill into the peritoneum (the lining of the abdominal cavity) if you have a perforation. A material that performs a function similar to barium but that can dissolve in water (water-soluble contrast) may be used instead.
- Flexible sigmoidoscopy and colonoscopy may be used if your main symptom is bleeding from the intestine. These tests also may be done to look for narrow spots or growths in the intestine and to rule out ulcerative colitis or cancer. But sigmoidoscopy and colonoscopy are not usually done while you are having an attack of diverticulitis because of the risk that the scope could tear the lining of the colon (perforation). If this happens, the infection could spill into the peritoneum (the lining of the abdominal cavity). This would cause a more serious infection.
See the topic Diverticular Bleeding for more information.
You may have a brief (acute) bout of diverticulitis that goes away after treatment with antibiotics and a liquid diet. But in some cases the condition occurs off and on (intermittently) over the long term (chronic). Treatment is the same in both cases, unless complications occur.
Treatment for diverticulitis depends on how bad your symptoms are. If the pain is mild, you are able to drink liquids, and you have no signs of complications, treatment may include:
- Medicines such as antibiotics and pain relievers.
- Changes in diet, starting with a clear-liquid or bland diet that is low in fibre until the pain goes away, then increasing the amount of fibre.
If the pain is severe, you are not able to drink liquids, or you have complications of diverticulitis, a hospital stay is needed. Treatment will include:
- Antibiotics given in a vein (intravenous, or IV).
- Intravenous fluids and nutrition only (no food or drink by mouth) for up to a week to allow the bowel to rest.
Treatment may also include:
- Keeping the stomach empty by sucking out the contents through a tube passed up the nose and down the throat into the stomach (nasogastric or NG tube). This may be needed if you are vomiting or have abdominal swelling.
- Doing surgery either for complications of diverticulitis or if you have had repeated attacks that are not helped by changing your diet. Overall, fewer than 6 out of 100 people who have diverticulitis need surgery.footnote 3
Most cases of promptly treated diverticulitis will improve in 2 to 3 days. If your doctor prescribed antibiotics, take them as directed. Do not stop taking them just because you feel better.
Treatment after recovery from an attack of diverticulitis is aimed at preventing another attack. Treatment may include:
- Gradually increasing the amount of fibre in the diet through fruits, vegetables, wheat bran, and possibly the regular use of a fibre supplement.
- Getting plenty of fluids daily.
- Having regular doctor visits to monitor your condition. If you have diverticulitis, the doctor may see you about 2 days after treatment begins to make sure you are improving. A colonoscopy or barium enema X-ray probably will be done about 6 weeks later, after symptoms are under control, to look for any other problems, such as inflammatory bowel disease or colon cancer.
Treatment if the condition gets worse
In some cases, complications of diverticulitis, such as an abscess, perforation, or bowel obstruction, can occur. Surgery to remove the affected part of the intestine usually is needed to treat these conditions.
Non-urgent (elective) surgery also may be done for diverticulitis if you have had two or more severe attacks, are younger than age 40, or have an impaired immune system.
To help prevent diverticulitis:
- Eat a high-fibre diet that is low in fat and red meat.
- Drink plenty of water.
- Exercise regularly.
Home treatment may help you control symptoms of diverticulitis or reduce the chance of having additional attacks of diverticulitis.
To reduce abdominal pain caused by mild diverticulitis:
- Apply a heating pad to your abdomen to relieve mild cramps and pain.
- Try relaxation techniques (such as slow, deep breathing in a quiet room or meditation) to help reduce mild pain.
- Use a non-prescription pain medicine such as acetaminophen (for example, Tylenol). Be safe with medicines. Read and follow all instructions on the label.
- If these techniques do not help and your pain increases, call your doctor to see whether prescription pain medicine is needed.
When you are feeling better, you can do some things to help prevent another attack. You may want to:
- Eat a high-fibre diet. Whole-grain breads and cereals, brown rice, and fresh fruits and vegetables can all be part of a high-fibre diet.
- Practice healthy bowel habits, such as eating at regular times, not straining during a bowel movement, and getting plenty of fluids each day.
Do not use laxatives or enemas unless your doctor prescribes them. If you use laxatives too often, you can become dependent on them for bowel movements. If you are having a sudden (acute) attack of diverticulitis, laxatives or enemas can make the pain worse.
Medicines to stop infection and to control symptoms often are used to treat attacks of diverticulitis.
- Antibiotics are given to treat the infection causing the attack.
- Prescription pain relievers sometimes are needed if non-prescription pain relievers cannot control the pain.
What to think about
Medicines are not used to prevent future attacks of diverticulitis. Prevention depends on increasing the amount of fibre in your diet and practising healthy bowel habits.
Surgery for diverticulitis involves removing the diseased part of the colon. You may decide to have surgery for diverticulitis if you have:
- Repeated attacks of diverticulitis. Surgery to remove the diseased part of the colon often is recommended if you have two or more severe attacks.
- A high risk of repeated attacks (such as in people younger than age 40, or people with an impaired immune system).
- An abnormal opening (fistula) that has formed between the colon and an adjacent organ, most commonly the bladder, uterus, or vagina.
Surgery for diverticulitis, in which the infected part of the colon is removed, may be required if you have complications, including:
- An infected pouch (diverticulum) that has ruptured into the abdominal cavity, especially if a pocket of infection (abscess) has formed. In some cases, an abscess can be drained without surgery. (See Other Treatment.)
- An infection that has spread into the abdominal cavity (peritonitis).
- A blocked colon (bowel obstruction) or a narrow spot in the colon (stricture).
- Infection that has spread through the blood to other parts of the body (sepsis).
- Repeated problems with bleeding or severe bleeding that does not stop with other treatments.
Overall, fewer than 6 out of 100 people who have diverticulitis need surgery.footnote 3
Surgical treatment involves removing the diseased part of the large intestine (partial colectomy) and reconnecting the remaining parts. Depending on the severity and nature of the symptoms, more than one surgery may be needed to correct the problem. When multiple surgeries are needed, the person usually has a colostomy during the time between surgeries. A colostomy is a surgical procedure in which the upper part of the intestine is sewn to an opening made in the skin of the abdomen. Stool passes out of the body at this opening and into a disposable bag. Usually the colostomy is removed at a later time and the intestine is reconnected.
Surgical treatment of diverticulitis, called bowel resection, involves the removal of the diseased part of the large intestine.
What to think about
People who have mild, brief attacks and who are willing to try long-term dietary changes may be able to avoid surgery. See the Prevention section of this topic for more information on diet.
If you have multiple attacks of diverticulitis, surgery may be appropriate.
Draining an abscess
In some cases of diverticulitis, a pocket of infection (abscess) in the abdomen heals on its own. At other times it can be drained without surgery. A needle is passed through the skin into the abscess, and the liquid containing the infection is drained. A computed tomography (CT) scan is used to help the doctor guide the needle into the abscess. Sometimes a plastic drain is placed temporarily in the abdomen to drain the abscess.
A blocked colon can sometimes be treated with bowel rest. You are not given anything to eat but instead receive fluids and nutrients through a tube connected to a vein. Suction through a tube placed in the nose and down into the stomach may be needed to keep the stomach emptied of digestive juices.
After 2 to 3 days of bowel rest, you are given something to eat. If the obstruction has cleared up, no surgery is needed. If the obstruction remains, bowel rest may be continued. If repeated periods of bowel rest fail to clear up the obstruction, surgery to remove the diseased part of the colon may be considered.
- Humes D, Spiller RC (2016). Colonic diverticular disease: Medical treatments for acute diverticulitis. BMJ Clinical Evidence. http://clinicalevidence.bmj.com/x/systematic-review/0405/overview.html. Accessed April 14, 2016.
- Strate LL, et al. (2011). Use of aspirin or nonsteroidal anti-inflammatory drugs increases risk for diverticulitis and diverticular bleeding. Gastroenterology, 140(5): 1427–1433.
- Harford WV (2010). Diverticulosis, diverticulitis, and appendicitis. In EG Nabel, ed., ACP Medicine, section 4, chap. 12. Hamilton, ON: BC Decker.
Other Works Consulted
- Fox JM, Stollman NH (2010). Diverticular disease of the colon. In M Feldman et al., eds., Sleisenger and Fordtran's Gastrointestinal and Liver Disease, 9th ed., vol. 2, pp. 2073–2089. Philadelphia: Saunders.
- Travis AC, Blumberg RS (2012). Diverticular disease of the colon. In NJ Greenberger et al., eds., Current Diagnosis and Treatment: Gastroenterology, Hepatology, and Endoscopy, 2nd ed., pp. 259–272. New York: McGraw-Hill.
Current as of: August 12, 2019
Author: Healthwise Staff
Adam Husney MD - Family Medicine
Anne C. Poinier MD - Internal Medicine
E. Gregory Thompson MD - Internal Medicine
Jerome B. Simon MD, FRCPC, FACP - Gastroenterology
Current as of: August 12, 2019