Home » Conditions Treated » Diverticulitis


Colonic diverticuli are small pouches or sacs that protrude outwards from the colon wall. Although they can be found in any part of the colon by far and away the most commonly involved segment is the sigmoid colon. It is believed that the great majority of diverticuli are acquired, meaning that they develop during the course of a person’s life. Although no one is certain, most experts believe that diverticuli form as a result of high pressure in the colon that develops when the large bowel contracts. The colon moves stool towards the anus by periodically contracting in a sequential fashion. These contractions temporarily raise the pressure in the colon. In some patients the pressures that develop can be quite high and it is thought that over the course of years the outpouchings slowly develop. Some experts believe the typical low fiber Western diet results in hard dense stools and contributes to the development of diverticuli since the colon must generate higher pressures to move hard stool through the bowel. The rate of diverticulosis in non-vegetarians is almost 3 times higher than in vegetarians. It is estimated that at least 30 % of Americans over the age of 60 and perhaps 60 % of those over 80 have “diverticulosis” which is the name given to patients who have diverticuli in one or more parts of the colon.

Acute Diverticulitis

In some patients with diverticulosis the colon wall becomes inflamed and a small perforation or hole may develop in a diverticulum that leads to an infection in the abdomen called “diverticulitis”. The most common symptoms of acute diverticulitis are lower left abdominal pain and fever. Other symptoms that may develop include a change in bowel habits, swelling of the abdomen, and nausea and vomiting. Currently, the diagnosis is almost always made with a CT scan of the abdomen which shows characteristic signs of thickening and inflammation of the colon wall. Attacks of diverticulitis can be classified as simple or complex. Thankfully, the majority are simple attacks that can be treated with antibiotics and restriction of diet alone. These episodes most often resolve within a week although some may require several weeks of antibiotics. In most patients the abdominal pain and other symptoms are much improved within 48 hours. The majority of patients with simple attacks are treated as outpatients with oral antibiotics. Some patients with simple attacks require hospitalization and intravenous antibiotics. These patients are usually discharged once the fever and abdominal pain has resolved and are continued on oral antibiotics for at least a week.

Complex Diverticulitis

Unfortunately, some patients have complex attacks of diverticulitis that are more difficult to treat; these patients all require hospitalization. For example, an abscess can develop next to the inflamed colon that may not go away with antibiotics alone. Large abscesses are most often treated with a drainage tube that is placed through the abdominal wall or buttocks by a radiologist. Typically, the tube stays in for a week or longer. In most cases an emergency operation can be avoided, however, most surgeons advise an elective colon resection after resolution of the acute abscess and diverticulitis in order to prevent future problems. Very rarely, an urgent operation is needed to drain an abscess and, possibly, to remove the diseased bowel and/or make a temporary colostomy. A very small number of patients with diverticulitis develop diffuse peritonitis with severe widespread abdominal pain, high fever, and other signs of severe illness. These patients almost always require immediate surgery. Another complex problem that can arise in patients with diverticulitis is an abnormal connection or fistula between the colon and the urinary bladder, another piece of intestine, the vagina, or the abdominal wall. The most common type is a colon to bladder fistula (colovesical fistula) that is usually discovered when patients note they are passing a combination of gas and urine when urinating. Patients with colovesical fistulas may also develop difficult to treat and frequent urinary infections. Patients with a diverticular fistula require an elective colon resection to resolve this problem. Rarely, patients with acute diverticulitis may develop a complete obstruction that will require surgery to resolve (see Other Diverticular Disease section).

There is a group of patients with acute diverticulitis without a sizable abscess, fistula, diffuse peritonitis, or obstruction whose attacks do not readily resolve. These patients may have persistent symptoms or develop recurrent symptoms soon after completing the prescribed course of antibiotics. In some cases it may take months of treatment with different antibiotics to get the patient over the episode. These attacks are complex from the standpoint of being persistent. Some of these patients may have small abscesses that are judged too small to drain through the skin. Other patients, in addition to persistent symptoms, are repeatedly found to have air outside of the colon wall on CT scan (a sign of perforation). These patients, because of their complex first attack, are more likely to have future attacks and may be best off having an elective colon resection without waiting for a second or third attack to develop.

Colon Screening After Diverticulitis

Patients with diverticulitis who have never had a colonoscopy or other colon screening examination need to have a colonoscopy done a few months after their first attack to rule out colon tumors. Rarely, colon cancers can be confused with diverticulitis on CT scans. The colon evaluation is not done during or immediately after an attack because of fear that the examination may re-activate the diverticulitis. The alternative screening methods are barium enema and virtual CT scan.

When is Surgery Necessary?

Surgery is not advised for patients who have had a single attack of simple diverticulitis. In these patients no further attacks occur in between 40 and 70 percent of patients. These patients should undergo standard colonoscopy for colorectal polyps and cancer at the standard intervals. The risk of future attacks of diverticulitis increases notably in patients who have had 2 discrete attacks. Most patients who have multiple attacks of diverticulitis have attacks similar to their first, however, in a small percentage a more complex attack may develop. It is very important that patients undergo CT scans when they have their second, third, or later attack of diverticulitis to confirm the diagnosis and also to make sure that an abscess has not developed. Most experts agree that elective surgery to remove the involved colon is reasonable after 2 episodes. After 3 clear cut episodes it can be confidently predicted that future attacks will develop and for this reason surgery is recommended.

One factor that should be taken into account when making a decision about surgery is the length of time between attacks. If the interval is 3 to 5 years and the attacks have been mild and easy to treat then a patient may decide to avoid surgery and to take their chances that there will be few future episodes. If, however, the interval between attacks is 3-6 months or is shortening with each attack then a very strong case can be made that surgery is the best course of action. Another factor that should be considered is the nature of recurrent attacks. Patients whose attacks become more difficult to treat or who have urinary symptoms (urinary frequency or painful urination) run a higher risk that an abscess or fistula may develop.

Operations for Diverticulitis

A basic principle of surgery for diverticulitis is that the chances of needing a temporary colostomy or ileostomy is much lower when a colorectal resection is done electively a time when the patient is not having in the midst of an attack. Surgery is more difficult in the setting of acute inflammation and an active infection.

Elective Operations

The ideal operation for a patient with diverticulitis is one where the diseased segment of colon is resected and the remaining ends of the large bowel are rejoined together without a temporary colostomy or ileostomy. This operation is possible for the great majority of patients who have an elective colon resection between attacks. However, in about 5 to 8 percent of elective resection patients, although it is possible to reconnect the 2 ends of the bowel, a temporary stoma (ileostomy or colostomy) is made nonetheless to divert the stool away from the new anastomosis. The protective stoma is helpful in this situation because it greatly decreases the chances of an anastomotic leak or abscess developing by preventing the stool from flowing past the rejoining point.

In a very small percentage of patients, after the bowel resection has been completed, the two ends of the large bowel are not rejoined and a colostomy is made instead. One reason for this decision may be the presence of severe inflammation or scarring that makes it difficult to construct the anastomosis. Another reason may be that the end of the remaining colon may be too short to reach the rectum. Yet another reason may be that the time required to perform the resection was so long that the surgeon and anesthesiologist decide that the bowel rejoining should be put off until another day so that the operation is completed sooner. A final reason for not rejoining the bowel ends is if the patient is unstable from the anesthesiologist’s point of view in regards to cardiac, pulmonary, or other reasons. A second separate operation to “take down” the colostomy and rejoin the bowel ends can be done at a later date for some of these patients.

In an exceedingly small percentage of patients (less than 1 %) who undergo elective surgery it may not be possible to resect and remove the diseased part of the colon because of severe disease. In these cases the surgeon may not be able to identify the tissue planes between the sigmoid colon and the other organs of the pelvis and lower abdomen. Whereas in most cases a safe approach can be found, in this very small subgroup, resection is not feasible without risking major injury to the bladder or the major blood vessels and other important structures of the pelvis. The only option in this situation is to make a colostomy to keep the stool away from the diseased part of the colon. In these patients it is usually possible to resect the diseased bowel and reconnect the 2 ends at a second operation done 6 to 12 months after the first procedure.

Emergency Operations

In very rare situations it is necessary to do surgery during an acute attack of diverticulitis. The most common reasons for this are: 1) diffuse peritonitis, 2) an abscess that cannot be drained with a tube placed through the abdominal wall, 3) failure to improve on intravenous antibiotics and 4) complete colonic obstruction. In the emergency setting the surgery is usually more difficult which increases substantially the chances that a stoma (colostomy) will be needed. If possible the diseased piece of colon is resected and the two ends rejoined. Even when this is possible a temporary stoma (ileostomy) is usually made to protect the newly rejoined colon and rectum. It is more common in the emergency setting for the surgeon to do the colon resection and to make a stoma without performing an anastomosis. Most emergency surgery patients who have a colostomy can have the stoma removed and the large bowel ends re-connected at a second operation that can be safely done 3 to 6 months later.

Surgical Method and Approach

The great majority of elective operations for diverticulitis can be carried out laparoscopically. The advantages of minimally invasive operations include less pain, earlier bowel function recovery and earlier discharge from the hospital. The choice of surgical method, open or laparoscopic, does not influence the ability of the surgeon to do the bowel resection. In fact, the laparoscopic approach facilitates the mobilization of the splenic flexure portion of the colon which is required in the majority of patients in order to safely rejoin the two bowel ends. If severe inflammation is found in the pelvis and it proves necessary to convert a laparoscopic case to open surgical methods the patient still benefits as long as the part of the operation that is outside the pelvis is completed laparoscopically. In this situation the final incision is usually about 11 cm long as opposed to the incision required to perform the operation using fully open methods (on average 22-26 cm long). This use of both laparoscopic and open methods is called the hybrid approach. In a small percentage of patients with severe disease a fully open operation may be the best choice.

Other Diverticular Disease


A small percentage of diverticulosis patients develop heavy rectal bleeding. For reasons that are unknown, major bleeding does not occur during an attack of diverticulitis. Although most bleeding episodes stop spontaneously some patients bleed repeatedly and require blood transfusions or other treatment. Because bleeding can occur in any part of the colon, when patients develop heavy rectal bleeding doctors must determine the location and, if possible, the cause of the hemorrhage. There are several ways to evaluate patients with severe bleeding. Colonoscopy is one method that can be used to locate the bleeding site. Another method, called angiography, involves injection of contrast into the bloodstream after which X-rays movies of the blood vessels that supply the colon are carried out. If the bleeding is active and heavy enough the contrast can be seen “pooling” in the colon at the bleeding site on the x-ray. These x-rays reveal which part of the colon is bleeding. The final diagnostic option is a nuclear bleeding scan. In this test a radioactive “marker” is intravenously injected after which a body scanner is used to look for pooling of the contrast in the abdomen. If the patient is bleeding at the time of the scan and is heavy enough then pooling will be seen. The location of the pooled blood provides clues as to which part of the intestine is bleeding.

Patients who have multiple bleeding events or severe hemorrhage may require treatment. Surgical resection of a limited length of the colon will deal with the problem provided the bleeding segment has been identified preoperatively. In patients who require surgery in whom it is not possible to identify which part of the colon is bleeding, the entire colon or almost the whole colon is surgically removed. Depending on the patient’s condition, age, and other medical problems, the remaining bowel ends may be rejoined (anastomosis) or a temporary colostomy or ileostomy may be constructed. In the setting of heavy acute bleeding “open” large incision surgery is usually performed although in a minority of cases laparoscopic methods may be used.

There are 2 non-surgical treatment methods that can also be used to treat heavy gastrointestinal bleeding. Both methods involve angiography. In one, small coils or sponges are injected through the angiography catheter directly into the bleeding vessel in an effort to obstruct the vessel and stop the bleeding (called embolization). In the second method, after the angiography catheter has been inserted into the artery that is bleeding, medicines that cause constriction of blood vessels are injected directly with the hope that the bleeding will cease.


Diverticulitis usually results in thickening of the colon wall. In a small number of patients who have a history of multiple attacks the bowel wall gets so thick that it narrows the colon segment greatly. In some a complete obstruction can develop. Rarely, this type of obstruction develops in patients who have never had a recognized attack of diverticulitis. Patients with acute obstruction stop having bowel movements. Over the course of days, the abdomen becomes distended and swells. This condition is most often diagnosed with abdominal X-rays or a CT scan. Most patients with large bowel obstruction require urgent or emergent surgery at which time, ideally, the obstructed and narrowed segment of colon is removed. If possible, the remaining ends of the bowel are rejoined immediately. Unfortunately, in some patients this may not be possible or advisable; in this situation a temporary colostomy (colon) or ileostomy (small bowel) is constructed.

In some diverticulitis patients with obstruction it may not be possible to remove the diseased part of the colon at the initial operation. The most common reason is severe inflammation and adhesions between the diseased colon and the bladder or other pelvic tissues that make surgical dissection extremely difficult and hazardous. In these situations a colostomy is made which diverts the intestinal flow away from the obstructed segment and through the abdominal wall (see colostomy section). It is usually possible to do second operation months later at which time the colostomy is closed so that the patient can go to the bathroom normally.

What Our Patient’s Say…

Our family wishes to express our heartfelt appreciation for the kindness, excellent care and wisdom our mother, Jean Broussard, received during her hospitalization.

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