Diverticulitis

Gross pathology of a longitudinally opened colon (inside/mucosa at top and outside/serosa at bottom), showing diverticulitis with two diverticular abscesses (white arrows). The dark coloration at right is previous colon tattooing for localization.

In complicated diverticulitis, an inflamed diverticulum can rupture, allowing bacteria to subsequently infect externally from the colon. If the infection spreads to the lining of the abdominal cavity (the peritoneum), peritonitis results. Sometimes, inflamed diverticula can cause narrowing of the bowel, leading to an obstruction. In some cases, the affected part of the colon adheres to the bladder or other organs in the pelvic cavity, causing a fistula, or creating an abnormal connection between an organ and adjacent structure or another organ (in the case of diverticulitis, the colon, and an adjacent organ).Related pathologies may include:[9]

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

It is unclear what role dietary fiber plays in diverticulitis.[10] It is often stated that a diet low in fiber is a risk factor; however, the evidence to support this is unclear.[10] There is no evidence to suggest that the avoidance of nuts and seeds prevents the progression of diverticulosis to an acute case of diverticulitis.[5][13] In fact, it appears that a higher intake of nuts and corn could help to avoid diverticulitis in adult males.[13]

Four classifications by severity have been published recently in the literature. The most recent and widely accepted is as follows:[20]

• Stage 0 – asymptomatic diverticulosis
• Stage 1a – uncomplicated diverticulitis
• Stage 1b – diverticulitis with phlegmonous peridiverticulitis
• Stage 2a – diverticulitis with concealed perforation, and abscess with a diameter of one centimeter or less
• Stage 2b – diverticulitis with abscess greater than one centimeter
• Stage 3a – diverticulitis with symptoms but without complications
• Stage 3b – relapsing diverticulitis without complications
• Stage 3c – relapsing diverticulitis with complications

The severity of diverticulitis can be radiographically graded by the Hinchey Classification.[21]

The differential diagnoses include colon cancer, inflammatory bowel disease, ischemic colitis, and irritable bowel syndrome, as well as a number of urological and gynecological processes. In those with uncomplicated diverticulitis, cancer is present in less than 1% of people.[22]

People may be placed on a low-fiber diet.[23] It was previously thought that a low-fiber diet gives the colon adequate time to heal. Evidence tends to run counter to this, with a 2011 review finding no evidence for the superiority of low-fiber diets in treating diverticular disease, and that a high-fiber diet may prevent diverticular disease.[24] A systematic review published in 2012 found no high-quality studies, but found that some studies and guidelines favour a high-fiber diet for the treatment of symptomatic disease.[25] While it has been suggested that probiotics may be useful for treatment, the evidence currently neither supports nor refutes this claim.[26]

Mild uncomplicated diverticulitis without systemic inflammation should not be treated with antibiotics.[27][20][28] For mild, uncomplicated, and non-purulent cases of acute diverticulitis, symptomatic treatment, IV fluids, and bowel rest have no worse outcome than surgical intervention in the short and medium term, and appear to have the same outcomes at 24 months.[29] With abscess confirmed by CT scan, some evidence and clinical guidelines tentatively support the use of oral or IV antibiotics for smaller abscesses (<5 cm) without systemic inflammation, but percutaneous or laparoscopic drainage may be necessary for larger abscesses (>5 cm).[27][30] Emergency surgery is required for perforated diverticulitis with peritonitis.[27][30]

Indications for surgery are abscess or fistula formation; and intestinal rupture with peritonitis.[14] These, however, rarely occur.[14] Surgery for abscess or fistula is indicated either urgently or electively. The timing of the elective surgery is determined by evaluating factors such as the stage of the disease, the age of the person, their general medical condition, the severity and frequency of the attacks, and whether symptoms persist after the first acute episode. In most cases, elective surgery is deemed to be indicated when the risks of the surgery are less than the risks of the complications of diverticulitis. Elective surgery is not indicated until at least six weeks after recovery from the acute event.[31] Emergency surgery is indicated for an intestinal rupture with peritonitis.[32]

The first surgical approach consists of resection and primary anastomosis. This first stage of surgery is performed on people if they have a well-vascularized, nonedematous, and tension-free bowel. The proximal margin should be an area of the 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.[33]

Diverticulitis surgery consists of a bowel resection with or without colostomy. Either may be done by the traditional laparotomy or by laparoscopic surgery.[34] The traditional bowel resection is made using an open surgical approach, called colectomy. During a colectomy, the person 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 with a removable bag attached to it. The waste is collected in the bag.[35]

However, most surgeons prefer performing the bowel resection laparoscopically, mainly because postoperative pain is reduced with faster recovery. Laparoscopic surgery is a minimally invasive procedure in which three to four smaller incisions are made in the abdomen or navel. After incisions into the abdomen are done, placement of trocars occurs which allows a camera and other equipment entry into the peritoneal cavity. The greater omentum is reflected and the affected section of the bowel is mobilized.[29] Alternately, laparoscopic sigmoid resection (LSR) compared to open sigmoid resection (OSR) showed that LSR is not superior over OSR for acute symptomatic diverticulitis. Furthermore, laparoscopic lavage was as safe as resection for perforated diverticulitis with peritonitis.[36]

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. The maneuvers are the retraction of the colon, the division of the attachments to the colon, and the dissection of the mesentery.[37] 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. After resection of the affected bowel segment, an anvil and spike are used to anastomose the remaining segments of the bowel. Anastomosis is confirmed by filling the cavity with normal saline and checking for any air bubbles.[29]

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.[38]

The colostomy is usually temporary, but it may be permanent, depending on the severity of the case.[39] In most cases several months later, after the inflammation has healed, the person undergoes another major surgery, during which the surgeon rejoins the colon and rectum and reverses the colostomy.