Diverticulitis

Diverticulitis
Large bowel (sigmoid colon) showing multiple diverticula. The diverticula appear on either side of the longitudinal muscle bundle (taenium).
Classification and external resources
ICD-10	K57
ICD-9	562
DiseasesDB	3876
MedlinePlus	000257
eMedicine	med/578
MeSH	D004238

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.

People often have left lower quadrant abdominal pain and tenderness, fever, and an increased white blood cell count. They may also complain of nausea or diarrhea; others may be constipated. The severity of symptoms depends on the extent of the infection and complications. Less commonly, an individual with diverticulitis may have right-sided abdominal pain. This may be due to the less common right-sided diverticula or a highly redundant sigmoid colon. Some patients report bleeding from the rectum.

Causes

The cause of diverticulitis is unknown. About 40% of the risk of disease is believed to be due to genetics while 60% is due to environmental factors.^[1] Obesity is another risk factor.^[1]

Diet

It is unclear what role dietary fiber plays in diverticulitis.^[1] It is often stated that a diet low in fiber is a risk factor; however, the evidence to support this is unclear.^[1]

There is no evidence to suggest that the avoidance of nuts and seeds prevents the progression of diverticulosis to an acute case of diverticulitis.^[2] It appears in fact that a higher intake of nuts and corn could help to avoid diverticulitis in adult males.^[2]

Pathophysiology

Diverticulitis is believed to develop due to changes inside the intestines including high pressures due to faulty contracting of the intestines.^[3]

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.

Diagnosis

Diverticulitis in the left lower quadrant as seen on CT scan

Diverticulitis on CT scan in coronal view

People with the above symptoms are commonly studied with computed tomography, or CT scan.^[4] 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.^[5] The diagnosis of acute diverticulitis is made confidently when the involved segment contains diverticulae.^[6] 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.

Other studies, such as barium enema and colonoscopy are contraindicated in the acute phase of diverticulitis due to the risk of perforation.

Differential diagnosis

The differential diagnosis includes colon cancer, inflammatory bowel disease, ischemic colitis, and irritable bowel syndrome, as well as a number of urological and gynecological processes.

Treatment

Most cases of simple, uncomplicated diverticulitis respond to conservative therapy with bowel rest. People may be placed on a low residue diet.^[7] This low-fiber diet gives the colon adequate time to heal.

Antibiotics

If bacterial infection is suspected, antibiotics may be used.^[8] 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.^[9]

Surgery

Surgery is often not needed.^[3] Complications, such as peritonitis, abscess, or fistula may require surgery, either immediately or on an elective basis. 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 persist 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 resulting from complications of the condition. Elective surgery may be performed at least six weeks after recovery from acute diverticulitis.^[10]

Emergency surgery is necessary for people whose intestine has ruptured; intestinal rupture always results in infection of the abdominal cavity.^[11] 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.^[12]

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.^[13] 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.^[14]

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.^[15] 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.

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 to reverse the colostomy. The surgeon makes an opening in the abdominal wall (a colostomy) which helps clear the infection and inflammation. The colon is brought through the opening and all waste is collected in an external bag.^[16]

The colostomy is usually temporary but it may be permanent depending on the severity of the case.^[17] 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.

Complications

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.

• Bowel obstruction
• Peritonitis
• Abscess
• Fistula
• Bleeding
• Strictures

Epidemiology

Diverticulitis most often affects middle-aged and elderly persons, though it can occur in younger people as well.^[18] Abdominal obesity may be associated with diverticulitis in younger patients, with some being as young as 20 years old.^[19]

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% will go on to develop diverticulitis within their lifetimes.

References

External links

• Health and Disease Information on Diverticulitis at Penn State University
• Diverticulosis and Diverticulitis at NIDDK
• Diverticulitis at Mayo Clinic
• Staging of Acute Diverticulitis online calc