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Large bowel (sigmoid colon) showing multiple diverticula. The diverticula appear on either side of the longitudinal muscle bundle (taenium).
Diverticulitis is a common digestive disease which involves the formation of pouches (diverticula) within the bowel wall. This process is known as diverticulosis, and typically occurs within the large intestine, or colon, although it can occasionally occur in the small intestine as well. Diverticulitis results when one of these diverticula becomes inflamed.
Signs and symptoms 
Patients often present with the classic triad of left lower quadrant pain, fever, and leukocytosis (an elevation of the white cell count in blood tests). Patients may also complain of nausea or diarrhea; others may be constipated.
Less commonly, an individual with diverticulitis may present with right-sided abdominal pain. This may be due to the less prevalent right-sided diverticula or a very redundant sigmoid colon. Some patients report bleeding from the rectum.
The most common symptom of diverticulitis is abdominal pain. The most common sign is tenderness around the left side of the lower abdomen. If infection is the cause, then nausea, vomiting, fever, cramping, and constipation may occur as well. The severity of symptoms depends on the extent of the infection and complications. Diverticulitis may worsen throughout the first day, as it starts as small pains and/or diarrhea, and may slowly turn into vomiting and sharp pains.
Most people with diverticulosis do not have any discomfort or symptoms; however, symptoms may include mild cramps, bloating, and constipation. Other diseases such as inflammatory bowel disease (IBD) and stomach ulcers cause similar problems, so these symptoms do not always mean a person has diverticulosis.
The development of colonic diverticulum is thought to be a result of raised intraluminal colonic pressures. The sigmoid colon (Section 4) has the smallest diameter of any portion of the colon, and therefore the portion which would be expected to have the highest intraluminal pressure. The claim that a lack of dietary fiber, particularly non-soluble fiber (also known in older parlance as "roughage") predisposes individuals to diverticular disease was long accepted within the medical literature. However, the first study to specifically test the theory has found that "A high-fiber diet and increased frequency of bowel movements are associated with greater, rather than lower, prevalence of diverticulosis."
Foods such as seeds, nuts, and corn were, in the past, thought by many health care professionals to possibly aggravate diverticulitis. However, recent studies have found no evidence that suggests the avoidance of nuts and seeds prevents the progression of diverticulosis to an acute case of diverticulitis. Not only has this research shown that they do not appear to be aggravating the diverticulitis, but it appears that a higher intake of nuts and corn could in fact help to avoid diverticulitis in male adults.
People with the above symptoms are commonly studied with a computed tomography, or CT scan. The CT scan is very accurate (98%) in diagnosing diverticulitis. In order to extract the most information possible about the patient's condition, thin section (5mm) transverse images are obtained through the entire abdomen and pelvis after the patient has been administered oral and intravascular contrast. Images reveal localized colon wall thickening, with inflammation extending into the fat surrounding the colon. The diagnosis of acute diverticulitis is made confidently when the involved segment contains diverticulae. CT may also identify patients with more complicated diverticulitis, such as those with an associated abscess. It may even allow for radiologically guided drainage of an associated abscess, sparing a patient from immediate surgical intervention.
Differential diagnosis 
Most cases of simple, uncomplicated diverticulitis respond to conservative therapy with bowel rest and antibiotics. Despite being recommended by several guidelines, the use of antibiotics in mild cases of uncomplicated diverticulitis is supported with only "sparse and of low quality" evidence, with no evidence supporting their routine use. However, recurring acute attacks or complications, such as peritonitis, abscess, or fistula may require surgery, either immediately or on an elective basis.
Diverticulitis surgery may be elective or may be a medical emergency. Whether the elective surgery should be performed is decided by external factors such as the stage of the disease, the age of the patient and his or her general medical condition, as well as the severity and frequency of attacks or if the symptoms persisted after a first acute episode. In most cases, the decision to perform elective surgery is taken when the risks of the surgery are smaller than the ones resulted from the complication of the condition. Elective surgery may be performed at least six weeks after recovery from acute diverticulitis.
Emergency surgery is necessary for people whose intestine has ruptured; intestinal rupture always results in infection of the abdominal cavity. During emergency diverticulitis surgery, the ruptured section is removed and a colostomy is performed. This means that the surgeon will create an opening between the large intestine and the surface of the skin. The colostomy is closed in about 10 or 12 weeks in a subsequent surgery in which the cut ends of the intestine are rejoined.
The first surgical approach consists in the resection and primary anastomosis. This first stage of surgery is performed on patients with a well vascularized, nonedematous and tension-free bowel. The proximal margin should be an area of pliable colon without hypertrophy or inflammation. The distal margin should extend to the upper third of the rectum where the taenia coalesces. Not all of the diverticula-bearing colon must be removed, since diverticula proximal to the descending or sigmoid colon are unlikely to result in further symptoms.
Diverticulitis surgery can be done in two ways: through a primary bowel resection or through a bowel resection with colostomy. Both bowel resections may be done in the traditional way or by laparoscopic surgery. The traditional bowel resection is made using an open surgical approach, called colectomy. During a colectomy, the patient is placed under general anesthesia. A surgeon performing a colectomy will make a lower midline incision in the abdomen or a lateral lower transverse incision. The diseased section of the large intestine is removed and then the two healthy ends are sewn or stapled back together. A colostomy may be performed when the bowel has to be relieved of its normal digestive work as it heals. A colostomy implies creating a temporary opening of the colon on the skin surface and the end of the colon is passed through the abdominal wall and a removable bag is attached to it. The waste will be collected in the bag.
However, most of the surgeons prefer performing the bowel resection laparoscopically mainly because the postoperative pain is reduced and the patient's recovery is faster. The laparoscopic surgery is a minimally invasive procedure in which three to four smaller incisions are made in the abdomen or navel.
All colon surgery involves only three maneuvers that may vary in complexity depending on the region of the bowel and the nature of the disease which are the retraction of the colon, the division of the attachments to the colon and the dissection of the mesentery. After the resection of the colon, the surgeon normally divides the attachments to the liver and the small intestine. After the mesenteric vessels are dissected, the colon is divided with special surgical staplers that close off the bowel while cutting between the staple lines.
Primary bowel resection 
The primary bowel resection is the standard procedure for diverticulitis. It consists of the removal of the diseased or ruptured part of the intestine which is then reconnected to healthy segments of the colon. This is called anastomosis. Depending on the patient's general medical condition, the procedure may be done traditionally, via a colectomy, or laparoscopically, which requires smaller incisions and allows for faster recovery.
Bowel resection with colostomy 
When excessive inflammation of the colon renders primary bowel resection too risky, bowel resection with colostomy remains an option. Also known as the Hartmann's operation, this is a more complicated surgery typically reserved for life-threatening cases.
The bowel resection with colostomy implies a temporary colostomy which is followed by a second operation which has the purpose to reverse the colostomy. The surgeon makes an opening in the abdominal wall (a colostomy) which helps clearing the infection and inflammation. The colon is brought out through the opening and all waste is collected into an external bag.
The colostomy is usually temporary but it may be permanent depending on the severity of the case. Most of the time, several months later after the inflammation has healed, the patient undergoes another major surgery during which the surgeon rejoins the colon and rectum and reverses the colostomy.
In complicated diverticulitis, bacteria may subsequently infect the outside of the colon if an inflamed diverticulum bursts open. If the infection spreads to the lining of the abdominal cavity, (peritoneum), this can cause a potentially fatal peritonitis. Sometimes inflamed diverticula can cause narrowing of the bowel, leading to an obstruction. Also, the affected part of the colon could adhere to the bladder or other organ in the pelvic cavity, causing a fistula, or abnormal connection between an organ and adjacent structure or organ, in this case the colon and an adjacent organ.
Diverticulitis most often affects middle-aged and elderly persons, though it can strike younger patients as well. Central obesity may be associated with diverticulitis in younger patients, with some being as young as 20 years old.
In Western countries, diverticular disease most commonly involves the sigmoid colon - section 4 - (95% of patients). The prevalence of diverticular disease has increased from an estimated 10% in the 1920s to between 35 and 50% by the late 1960s. 65% of those currently 85 years of age and older can be expected to have some form of diverticular disease of the colon. Less than 5% of those aged 40 years and younger may also be affected by diverticular disease.
Left-sided diverticular disease (involving the sigmoid colon) is most common in the West, while right-sided diverticular disease is more prevalent in Asia and Africa. Among patients with diverticulosis, 10–25% patients will go on to develop diverticulitis within their lifetimes.
Notable sufferers 
- Brock Lesnar, professional wrestler and former mixed martial artist.
- Eddie Van Halen, lead guitarist for rock and roll giants, Van Halen.
- Stewart Lee, comedian.
- Crawford Grimsley, retired professional boxer and kickboxer.
- Emmanuel Steward, boxing trainer, died of colon cancer complicated with diverticulitis.
- Don Cooper, former pitcher in Major League Baseball and the current pitching coach of the Chicago White Sox.
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