Diverticulitis and diverticulosis

If pressure builds up in the large intestine, small bubbles or bulges may form at weak spots in the intestinal wall. These tiny pouches are called diverticula.

Diverticulosis and diverticulitis share the common feature of diverticula, but they are different.

Diverticulosis vs. diverticulitis

Diverticulosis and diverticulitis are both categorized as diverticular diseases since they share the common feature of diverticula. However, they are separate conditions.

If you have diverticula along your large intestine, you have colonic diverticulosis. Diverticulosis simply means the “presence of” diverticula. Diverticulosis is not usually a problem and may not cause any symptoms.

If feces or particles can get trapped in the diverticula, they can become inflamed and infected. Diverticulitis refers to this infection or inflammation of the diverticula. Not all people who have diverticulosis will develop diverticulitis.

While colonic diverticulitis can occur anywhere along the large intestine, it tends to occur in the S-shaped sigmoid colon that makes up the last part of the large intestine.

Diverticulitis can be acute or chronic. Acute diverticulitis means you have a distinct, often severe attack or episode which can be cleared up with treatment. Chronic diverticulitis means that inflammation may go down but doesn’t fully clear up. It may come back again. Over time, chronic diverticulitis can cause other complications.

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Diverticulitis causes

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Experts are not completely sure what causes diverticulitis, but many think it happens when you don’t eat enough fiber.

Fiber is an important part of a healthy diet, and it can be found in fruits, vegetables, and whole grains. Your body does not digest fiber. Instead, fiber adds bulk to your stool and makes it softer and easier to pass.

Eating too little fiber can lead to constipation, which happens when your stool moves slowly through your large intestine and becomes dry and hard to pass. Your muscles have to strain to push the stool along, which increases the pressure in your large intestine. This can lead to diverticula forming. If feces or bad bacteria get into the diverticula, they can become inflamed and infected.

However, your fiber intake is not the only thing that determines whether you will develop diverticular disease. Experts have identified additional risk factors that increase your chance of developing diverticulitis. These include:

  • Genetics: Your genes can increase your risk for developing diverticular disease. Diverticulitis appears to be hereditary, meaning it can be passed from parent to child.
  • Having diverticulosis.
  • Age: Diverticulitis is most common in people over 50.
  • Obesity: Being severely overweight increases your risk for developing diverticulitis.
  • Smoking: Smokers are much more likely to develop diverticulitis than non-smokers.
  • Lack of exercise: Regular, vigorous exercise reduces your risk of diverticulitis.
  • Diet: Eating a low fiber, high fat diet increases your risk for diverticulitis.
  • Certain medications: Some medicines can increase your risk for diverticulitis. These include nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil and Motrin, opioids, steroids, and naproxen sodium (Aleve).

Diverticulosis and diverticulitis symptoms

Symptoms vary widely from person to person.

If you have diverticulosis, you may experience no symptoms at all. Otherwise, you may experience mild symptoms such as:

  • Mild cramps
  • Bloating
  • Constipation

However, these symptoms are similar to other conditions, such as irritable bowel syndrome (IBS) and ulcers. They do not necessarily mean you have diverticulosis.

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Symptoms of diverticulitis include:

  • Mild cramps or abdominal tenderness.
  • Abdominal pain: Usually, this pain persists for several hours or days, or until you have a bowel movement. Diverticulitis pain is usually located on the lower left side of your abdomen. However, you may also experience right-side abdominal pain, especially if you are of Asian descent.
  • Back pain: Cramps and abdomen pain caused by diverticulitis can radiate to your back, causing low back pain.
  • Change in bowel habit: You may experience constipation or, less commonly, diarrhea.
  • Diverticular bleeding: You may see bright red blood in your stool, which comes from bleeding diverticula.
  • Nausea, fever, or vomiting may occur if you have an infection.
  • Narrow or pellet-like stools: if you have advanced or severe diverticulitis, your large intestine may narrow, causing stool to become thin, narrow, or pellet-shaped.

The symptoms of diverticular disease may look like other health problems. Always see your healthcare provider to be sure.

You should seek emergency medical attention for diverticulitis if you experience one or more of the following:

  • Blood in stool.
  • Excessive vomiting or severe nausea.
  • Fever over 100.4 F.
  • Sudden and severe abdominal or back pain that worsens quickly.

These may be signs of diverticulitis complication or of another serious medication condition that requires attention.

Diverticulitis complications

Many cases of diverticulitis are mild and clear up with rest and antibiotics. However, left untreated, severe diverticulitis can develop complications:

Bowel obstruction. A bowel obstruction happens when the large intestine becomes blocked, preventing stool from passing. If you have chronic diverticulitis, excess scar tissue may eventually cause a bowel obstruction. A bowel obstruction is a serious medication condition. If the blockage is complete, you will need emergency surgery to clear the path.

Diverticulitis abscess. An abscess is a pus-filled pocket. Infected diverticula can become abscesses. Small abscesses can usually be treated with antibiotics, but a large abscess may need to be surgically drained or removed.

Fistula. A fistula refers to an abnormal pathway created between two organs. Sometimes, after a severe diverticulitis flare up, a fistula forms between the large intestine and nearby organs, such as the bladder, small intestine, or vagina. This can lead to painful urination or abnormal vagina discharge. Fistulas require surgery.

Diverticulitis rupture (perforation). If an abscess or weak spot in the large intestine tears, pus or stool can spill out into the abdominal cavity. This leads to peritonitis, or inflammation and infection of the abdominal cavity. Peritonitis can be life-threatening and requires immediate medical attention.

Diverticulitis diagnosis

Your doctor will take your medical history and will ask about any symptoms, including when they started and how long you’ve had them. As part of a physical exam, your doctor will feel your abdomen for masses or enlarged organs. You may also have a digital rectal exam (DRE). During this test, the doctor inserts a lubricated, gloved finger into your rectum to feel for any abnormal areas. If you have a vagina, your doctor may perform a pelvic exam to rule out problems with your reproductive system.

If your doctor suspects diverticulitis, they may order one or more of the following tests:

  • Blood or urine tests to check for infection.
  • Stool sample tests. A small stool sample can be tested for signs of infection or the presence of blood.
  • Pregnancy test, to rule out the possibility of pregnancy or of ectopic pregnancy, which can cause similar symptoms.
  • Liver enzyme test, to rule out problems with your liver.
  • Computed tomography (CT or CAT) scan. A CT scan created a detailed image of your organs and can be used to look for infected diverticula or abscesses.

  • Your doctor will use a thin, flexible tube with a light and camera (a sigmoidoscope) to examine your sigmoid colon for ulcers, polyps, bleeding, or inflamed diverticula. A sigmoidoscopy helps determine how severe your diverticulitis is.

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Diverticulitis treatment

Your treatment will depend on the severity of the diverticulitis and your symptoms.

Uncomplicated diverticulitis

If you have mild diverticulitis without complications, your doctor may recommend you follow a diverticulitis diet plan. This involves:

  • Liquid diet. A liquid diet involves avoiding solid foods and drinking clear liquids like broth, fruit juices without pulp, tea, gelatin, and other clear liquids for a few days. This gives your large intestine time to rest and heal.
  • Low fiber diet. After a few days on a liquid diet, your doctor may recommend a low fiber diet, which means eating low-fiber foods like eggs, cheese, rice, canned fruits and vegetables (without skins), and refined white bread or pasta. These foods are usually easy to digest.

Your doctor may also prescribe you antibiotics. Antibiotics can be used to treat infection, although they are usually not necessary in very mild cases. Commonly prescribed antibiotics include metronidazole (Flagyl), trimethoprim-sulfamethoxazole (Bactrim), ciprofloxacin (Cipro) or amoxicillin and clavulanic acid (Augmentin). 

Complicated diverticulitis

If you have a severe diverticulitis attack or are experiencing complications like bleeding or a bowel obstruction, you may need to be treated in a hospital. Treatment may involve:

  • Intravenous (IV) antibiotics. For severe diverticulitis, you may need to have antibiotics injected into your veins through an IV.
  • Surgical drainage. If you have a large abscess, your doctor will need to insert a tube into it to drain it.

Surgery for diverticulitis may be recommended if:

  • A bowel perforation has occurred.
  • A fistula has developed between the large intestine and another organ.
  • You have peritonitis.
  • You have a complete or partial bowel obstruction.


There are two types of surgery for diverticulitis:

Primary bowel resection. The infected or damaged part of your bowel is removed, and the remaining parts of your bowel are reattached. This allows you to have normal bowel movements. Your doctor may be able to perform this surgery laparoscopically, meaning only a few small incisions are made. This reduces scarring and recovery time.

Bowel resection with colostomy. Your surgeon removes the damaged or infected part of the colon. If there is too much inflammation and your doctor cannot connect the remaining colon segments, your surgeon will construct another path for waste to leave your body. This is known as a colostomy. It involves attaching the end of the colon to a small opening in the wall of your abdomen. A bag fits securely over the opening and collects the waste. In some cases, your surgeon may be able to go back in and reconnect the colon once the inflammation has gone down.

After surgery, you will need to rest lots and avoid lifting heavy objects. Your doctor may recommend that you come in six or more weeks after surgery for a colonoscopy. Your doctor looks at the entire length of your colon and rectum with a colonoscope, a thin, flexible, lighted tube with a small video camera on the end. Special instruments can be passed through the colonoscope to biopsy or remove any suspicious-looking areas such as polyps. Having a colonoscopy can help rule out colon cancer as a cause of symptoms.

Diverticulitis outlook and prevention

While there is no foolproof way to prevent diverticulitis, there are steps you can take to reduce your risk of developing it:

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  • Exercise daily. 30 minutes of vigorous exercise a day can help reduce your risk of developing diverticulitis.
  • Don’t smoke. Smoking increases your risk of developing diverticulitis. If you don’t smoke, don’t start. If you do smoke, consider joining a smoking cessation program.

  • Drink lots of water.
  • Eat a healthy, high-fiber diet. Try to eat fresh fruits, vegetables, and whole grains with every meal to make sure you’re getting enough fiber. Women should get around 25 grams of fiber per day, and men should get about 38 grams per day. You may want to talk to your doctor or a dietician about other changes that might help you get the right amount of fiber.
  • Consider making dietary changes. If you have had diverticulitis or have flare-ups, you may want to change your diet. Doctors used to recommend removing nuts, seeds, and popcorn from your diet, but new scientific research does not back this claim up. Try to keep a food journal where you track your food intake and symptoms to pinpoint what foods cause flare-ups for you.