Diverticulosis and Diverticulitis of the Colon

Diverticulosis and Diverticulitis

What is Diverticulosis?

The colon is not simply a hollow tube but rather a tubular organ with several layers comprising its wall. The inner most layer, called the mucosa is the lining of the colon and performs most of the metabolic function of absorbing water from the stool such that bowel movements are firm and well formed and not just liquid. Surrounding the mucosa are 2 layers of smooth muscle which serve to propel the contents of the colon further downstream to be eliminated from the body. This process, called peristalsis, is coordinated by a very complicated web of nerve fibers that are invested throughout the GI tract. The outermost layer of the colon is called the serosa. It is tough fibrous connective tissue that surrounds all of our organs and gives them strength. The serosal layer reflects onto itself to form a double layer of mesentery which holds the GI tract to the posterior abdominal wall. Within this mesentery, blood vessels and nerve fibers travel from their origins to the colon. These blood vessels penetrate the wall of the colon to provide oxygen and nutrients to the cells of the colon. At the sites where the blood vessels penetrate, there is a natural weakness in the wall which allows for the development of diverticuli. This is where the mucosa penetrates through the wall of the colon and forms a little pouch. The presence of diverticuli in the colon is referred to as diverticulosis. Diverticulitis is an inflammatory condition that occurs when one or more of these diverticuli become infected.

Who Gets Diverticulosis and Diverticulitis?

The incidence of Diverticulosis increases with age. In the United States, less than 10% of people under the age of 40 have diverticulosis, while by age 60 about half of Americans have the condition. Men and Women are affected about equally. People of all races are affected equally as well. The condition seems to have more to do with what Americans eat than what is in their genes.

Though controversial, it is believed that the development of diverticulosis has mostly to do with a lifetime consumption of a diet too low in fiber. While evolutionary design has provided humans with the ability to process both animal and vegetable matter for nourishment, we were designed to consume this nourishment in its natural state, not highly processed and cooked as we do. High amounts of natural fiber in our diets allows for the easy passage of stool as it is formed in our colons. A diet low in fiber leads to the development of relatively non-bulky hard stool which is more difficult to pass. As a result, pressure is increased in the colon and over years, this increased pressure in the colon creates these herniations of colonic mucosa through the wall of the colon, i.e. diverticuli.

About 10% of people with diverticulosis will go on to suffer diverticulitis. More on that below.

What are the Complications of Diverticulosis?

The mere presence of diverticulosis has no specific consequences and is completely asymptomatic. Diverticulosis occurs more commonly in the distal colon called the sigmoid colon, however the condition can occur anywhere in the colon. Diverticuli in the right colon have a greater propensity towards bleeding and the bleeding can be quite severe. However, diverticuli anywhere in the colon can bleed. Another cause of bleeding in the colon which may be indistinguishable from diverticular bleeding is arterio-venous malformations which are tiny abnormal communications between arteries and veins in the colon wall. In both situations bleeding is often brisk resulting in red blood per rectum as opposed to the black tarry stools that accompany bleeding from upper gastrointestinal sources such as the stomach or duodenum. Slower diverticular bleeds however may result in black stools. Hemorrhoids can also cause brisk bleeding though the source of the bleeding is usually obvious. Finally, tumors in the colon can also bleed but usually the bleeding is at a very low level and is chronic in nature. Very rarely do tumors cause brisk bleeding.

Diverticuli bleed because they form adjacent to blood vessels through natural weaknesses in the wall of the colon that occur where the blood vessels penetrate the colon wall to supply blood to the cells that make up the colon. Arterio-venous malformations bleed because thin walled veins are abnormally connected to small arteries where the blood is flowing under high pressure. The thin walled veins can then simply rupture. Hemorrhoids are essentially enlarged abnormal veins in the ano-rectum and bleed for more or less the same reason though they are not subjected to high arterial pressures. Tumors also contain abnormal blood vessels and therefore are just prone to bleeding.

What is Diverticulitis (already)?

As stated above about 10% or people with diverticulosis will develop diverticulitis. Diverticulitis occurs when one or more diverticuli become infected. It is felt that some particle of hard stool blocks the opening of the diverticulum and bacteria within the diverticulum then may grow and create an abscess. Inflammation that surrounds this abscess can be quite severe.

The abscess may perforate the wall of the colon causing leakage of stool and pus into the abdominal cavity. The abscess and inflammatory process may involve adjacent organs resulting in a fistula forming between the colon and the other organ. Organs involved typically include other areas of colon, small intestine, bladder or vagina in females.

There is some controversy as to whether seeds (poppy seeds, sesame seeds etc.) can cause diverticulitis by obstructing the lumen of a diverticulum. Patients with diverticulitis following recovery are placed on a diet that forbids these types of seeds. However, I have never seen a pathology specimen that revealed a sesame seed in the lumen of a diverticulum causing obstruction. I do not know of any such pathology report anywhere. Furthermore, some of the newer studies are showing that seeds of this type are actually beneficial in your diet as they are a source of fiber.

What are the symptoms of Diverticulitis?

Diverticulitis occurs most commonly in the sigmoid colon which is in the left lower portion of the abdomen. The most common symptom is pain. The pain is often severe, sharp to crampy and may be associated with nausea, vomiting and fever. The diagnosis is suggested on physical exam which reveals tenderness in the left lower quadrant of the abdomen possibly with rebound tenderness. CT scan confirms the diagnosis.

Diverticulitis may occur in other parts of the colon though much less frequently. Symptoms may mimic appendicitis if diverticulitis is present in the right colon or even ulcer disease or pancreatitis if diverticulitis is present in the transverse colon. Once again, CT will confirm the diagnosis.

Some other unusual symptoms may occur if diverticulitis has resulted in a fistula forming to another organ. A fistula to another area of colon may be asymptomatic. Air or stool coming from the bladder or the vagina may suggest a fistula from the colon to one of those organs. A fistula to the small bowel may result in diarrhea and weight loss from malabsorption or it may be asymptomatic.

What is the treatment of Diverticulosis and Diverticulitis?

Having diverticulosis requires no specific treatment except for maintaining a high fiber diet discussed below. Diverticular bleeding often stops by itself but sometimes can be very difficult to manage. It is first necessary to localize the source of the bleeding within the colon. Colonoscopy is the procedure of choice, but finding the source of bleeding during colonoscopy can be difficult it bleeding is severe. Often the situation is emergent and there is no time to prepare the colon. Colonoscopy can differentiate diverticular bleeding from bleeding resulting from an arterio-venous malformation. It can also control the bleeding with cautery introduced through the colonoscope.

A bleeding scan done in the nuclear medicine department of most hospitals utilizes your own blood cells tagged with a radioactive substance which can then be detected on the x-ray monitor. A source of bleeding will show up as an area of concentration of these tagged red blood cells. Though occasionally useful, most bleeding scans are non-diagnostic because the bleeding at the site just isn't rapid enough to be detected by this method.

Angiogram may be employed to inject contrast directly into the larger vessels which feed the bleeding site. The bleeding site can then be localized and small coils can be injected to occlude the bleeding vessel. This can be very hazardous in the intestine though, because in many areas, this may be the only small vessel supplying that small area of intestine. While occluding it will stop the bleeding, it may also result in infarction of that area of colon.

If bleeding is severe and the above methods are not successful in stopping it, surgery may be necessary. Even if unsuccessful in stopping the bleeding, hopefully one of those methods was successful in identifying the source of the bleeding. Then, the area of colon that needs to be removed will be relatively limited. Trying to identify source of bleeding within the colon during surgery, when the colon is full of blood can be very challenging. In the end, if the exact source cannot be clearly identified, it may be necessary to remove the entire colon.

Diverticulitis is not usually as dramatic as severe diverticular bleeding. While some patients with diverticulitis may present with fulminant peritonitis from perforation and go right to surgery, most are not that sick. As described above, most patients with diverticulitis are acutely ill and need to be hospitalized. They are placed on IV fluids and are not permitted to have anything by mouth so as to allow the GI tract to rest. Antibiotics are administered intravenously.

Surgery is indicated for perforated diverticulitis, repeated hospitalizations for diverticulitis over a short period of time or for complications of diverticulitis such as obstruction or fistula formation. Depending on the circumstances, the Laparoscopic approach may be acceptable, however in cases of obstruction, severe inflammation or fistula formation this may just not be feasible. In some patients a colostomy may be needed temporarily while the inflammation is allowed to heal. This may usually be reversed in three to six months and the reversal surgery is readily amenable to Laparoscopy allowing for a shorter recovery and rapid return to normal function. Also, with Laparoscopy, the midline wound need not be opened.

In some patients, in spite of perforation or other complications, it may be safe to put the colon back together again at the time of the initial surgery. In some of these patients, the small intestine may be brought through the abdominal wall and opened as an ileostomy. This allows for the colon to heal while the stool is diverted away from the repair out of the body. Reversal of the ileostomy may be performed in three to six weeks, once the anastomosis has healed. As well, this procedure does not require opening the midline wound. The small intestine is separated from the skin, the hole in the intestine is closed and the intestine is dropped back into the abdomen. The wound is then closed. Recovery is only a few days in the hospital.

How can I prevent Diverticulitis?

Now that you have read about all of these terrible complications of diverticulitis and are determined to avoid it, be encouraged to know that you can. Diverticular disease is a modern invention. As we have developed modern processes of refining and preparing food we have refined away to nutritive value of the foods we eat. White bread and bleached rice along with processed sugar and lots of burnt red meat is a recipe for diverticulitis. Here are some examples of high fiber foods that you can add to your diet which will help you avoid this condition.

Fruits: apples, pears, berries

Bread: whole wheat or other whole grain

Cereals: any made with whole grains, oatmeal

Vegetables: almost all vegetables are high in fiber particularly if they are uncooked, grilled or steamed. Boiling vegetables degrades their fiber content

Beans: red beans, kidney beans, black beans

Nuts: peanuts, cashews, almonds etc are all high in fiber, but may also be high in cholesterol

By making simple substitutions in the choices one makes for their diet, one can vastly change the probability of developing diverticular disease and its attendant complications.

This article should not be concluded without mentioning the benefit of regular exercise on promoting GI health as well as cardiovascular health and health in general. Walking promotes peristalsis and aids in digestion. Thus, the reason why most of us feel like going for a walk after a heavy meal. Walking after every meal would be a very good habit to get into.

I hope that I have answered most of the questions that you may have had, without adding to your confusion. As always, I welcome questions or comments.

Steven P. Shikiar, MD, FACS email