Diverticula are small pouches of tissue that bulge out through weak spots in the colon. People with diverticula are said to have diverticulosis. Figure 01 Diverticulosis is very common in the U.S. and other Western countries. An estimated half of all Americans between the ages of 60 and 80, and almost everyone older than age 80, has diverticulosis.
Diverticulitis is a serious, unpredictable, and potentially dangerous complication of diverticulosis that occurs when the diverticula become inflamed or infected.
An estimated 10% to 25% of people with diverticulosis develop diverticulitis. Diverticulitis can be treated with antibiotics, pain medications, and/or surgery.
Frequently, food residue gets lodged in diverticula, providing a good environment for bacteria to grow and multiply. In severe cases, bacterial infection may spread outside the colon into the abdominal space—a serious and potentially fatal condition called peritonitis.
With diverticulitis, the inflammation may be limited, or may be accompanied by abscesses, blockages, or tears in the wall of the colon.
Diverticulosis and diverticulitis are known together as diverticular disease. Diverticular disease most often occurs in those over 50 years of age, but is becoming more common in younger people.
An estimated 2% to 4% of younger people had diverticular disease in the late 1960s. In the early 1990s the incidence was estimated to have risen to between 12% and 30%. Diverticular disease in younger people is generally more aggressive, and often requires surgical treatment.
Figure 01. Diverticula in the colon
The underlying cause of diverticular disease is thought to be a low-fiber diet. Fiber is the undigestable part of the foods we eat. Fiber helps to soften stools and make them easier to pass through the colon. Fiber also helps prevent constipation.
Diverticular disease is common in industrialized countries where the diet consists predominantly of processed foods with relatively little fiber. Diverticular disease is rare in countries where people eat high-fiber diets with large amounts of fruits and vegetables.
Diverticula are thought to form when there is too much pressure in the colon. The stools of people who eat low-fiber diets are often hard and compact. To force these stools through the colon, the abdominal muscles must put additional pressure on the colon. This excess pressure causes weak spots in the wall of the colon to bulge out, much like an inner tube poking out of the weak spot in a bicycle tire as it is pumped up.
In rare cases, diverticular disease may be caused by a puncture of the colon with a foreign body, such as a fish bone.
The vast majority of people with diverticulosis have no symptoms.
Abdominal pain is usually the first symptom of complications caused by diverticulitis. Because most cases of diverticulitis affect the left side of the colon, the pain or tenderness is usually located around the left side of the lower abdomen.
When an infection is present, diverticulitis may also appear with fever, nausea, vomiting, chills, cramping, and constipation.
Diverticulitis can have severe complications that cause bloody stools, persistent constipation, and severe abdominal pain or tenderness. You should seek immediate medical attention if these symptoms appear. Table 01 The complications that cause these symptoms include lower intestinal bleeding, abscesses, perforations in the colon wall, peritonitis, fistula formation, or intestinal obstructions.
- Intestinal bleeding can be caused by blood vessels that burst within diverticula. The bleeding usually stops by itself, but in some cases surgery is necessary.
- An abscess is an infected area that fills with pus. Abscesses can cause swelling, and can destroy healthy tissue. A perforation in the wall of the colon can lead to an abscess. The larger the abscess, the greater the need for it to be drained though the skin or by means of surgery.
- Peritonitis is an infection that spreads outside of the colon to the abdominal space. If left untreated, peritonitis can be fatal.
- Fistulas are abnormal connections between organs or tissues. When infected tissues come in contact with each other, they may stick together, creating abnormal passageways between the organs. The most common fistulas that occur with diverticulitis are between the bladder, the small intestine, and in women, the vagina. Fistulas to the skin are very rare in diverticular disease.
- Scarring caused by diverticulitis can block the intestinal tract, requiring surgery. In most cases, the blockage only partially obstructs the colon. When the colon is completely obstructed, emergency surgery is required to prevent potentially fatal complications.
Table 1. Symptoms of Diverticular Disease
Diverticulitis Lower left abdominal tenderness or pain Fever Nausea Vomiting Chills Cramping Constipation Symptoms requiring immediate medical attention Bloody stools Persistent, high fever Persistent constipation Severe abdominal pain or tenderness
A diet low in fiber is the primary risk factor for diverticulosis. The average American diet contains roughly half the recommended amount of fiber needed to avoid diverticulosis. In areas of the word where diverticulosis is rare, the average daily intake of fiber is 40 g to 45 g. The average American diet, in contrast, contains about 20 g to 25 g of fiber per day.
At one time, doctors thought that some ethnic groups had a higher risk of developing diverticular disease. The most recent research, however, suggests that any difference between ethnic groups is due to differences in diet. For example, diverticular disease is rare in Africa, and was relatively uncommon among African-Americans until the second half of the 20th century. However, the rate of diverticular disease among African-Americans has steadily increased, and is now equal to that of the white population. This suggests that environmental factors such as diet play a larger role in the disease than genetic differences related to ethnicity.
Asian populations have a higher incidence of right-sided diverticula and diverticulitis. However, right-sided diverticulitis can be mistaken for appendicitis.
Because the initial symptoms of diverticular disease mimic those of many other digestive diseases, your physician will first take a medical history to help pinpoint the cause of your symptoms. The questions will include whether or not you have a personal and family history of diverticulosis, diverticulitis, or colorectal cancer. Your physician will also ask you about your bowel habits and diet as well as your symptoms, their severity, and how long or how frequently you’ve had them. He or she will ask you about drugs you may be currently using— especially those like aspirin or other non-steroidal anti-inflammatory drugs (NSAIDS) that can cause intestinal bleeding. Finally, your physician will ask about other conditions (such as pregnancy or HIV/AIDS) that would affect your symptoms or treatment.
You will next undergo a physical examination. Your physician will focus on your abdomen, looking for pain, tenderness, or rigidity around the left side of your lower abdomen, where most cases of diverticulosis and diverticulitis occur. The physical examination will also include a blood pressure test and close examination of your heart rhythm. In severe cases of diverticulitis, blood loss may cause potentially serious changes in blood pressure or heart rhythm. Finally, your physician may perform a digital rectal exam to look for tenderness, blockages, or bleeding.
Your physician may order blood tests to determine whether you have anemia, a clotting abnormality, or an electrolyte imbalance. These conditions may reflect more severe diverticular disease, and may require surgery.
Your physician may also order a CT scan of the abdomen and pelvis to determine the extent of the inflammation, and to identify complications such as abscesses. A CT scan is performed through a process in which three-dimensional x-ray images are made of the abdomen. It can be used to help determine the extent of the diverticulosis, to identify abscesses or perforations, and to determine whether surgery is an option.
While CT scanning is the test of choice, some places use ultrasound (sonography) instead. Diverticulosis is usually diagnosed when a patient is having a barium enema for some other reason, or during flexible sigmoidoscopy or coloscopy—procedures used to view the inside of the colon.
In some cases, your physician may order a colonoscopy to help identify bleeding sites within the colon. In a colonoscopy, a lighted tube attached to a small fiber optic camera is inserted into your rectum and slowly guided through your colon. A colonoscopy allows your physician to observe the interior of your entire colon. It is most often used to look for early signs of colorectal cancer, but it is also used to investigate the tissue damage associated with diverticulitis and to identify sites of bleeding within the colon. Once a site of bleeding has been pinpointed, your physician can use this information to help plan for surgery or other treatment.
If a colonoscopy does not identify the affected site, your physician may order a blood scan. In some cases, colonoscopy cannot identify the site of bleeding within the colon because of obstructions or interference by blood washing throughout the colon. In these cases, the physician may order a blood scan. A blood scan is a test in which the doctor injects a small amount of radioactively tagged red blood cells into one of your veins. The tagged blood spreads to the vessels in your colon. A scanner that can detect the radioactivity is then passed over your abdomen, and an image is created of the areas in your intestines in which blood is seeping into the colon.
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