With intravenous fluids for the next 24 hours, the patient's pain resolves. She's discharged with ciprofloxacin 500 mg twice a day and metronidazole 500 mg every 6 hours for seven days.
Six months later, Carol C. returns with worsening LLQ pain radiating to her back, 38.8°C fever and diarrhea (several semi-formed, non-bloody stools). Her blood pressure has dropped to 115/65 mm Hg. The examination indicates generalized abdominal peritonitis. An abdominal x-ray and CT scan report perforation of the sigmoid colon. After an urgent surgical consultation, Mrs. C. is administered intravenous (IV) cefotaxime 2 g every 8 hrs and metronidazole 50 mg IV every 6 hrs. During the emergency laparotomy that follows, surgeons remove 10 cm of the sigmoid colon, leaving her with a diverting colostomy and rectal stump. After two weeks, she's discharged home, with an outpatient colonoscopy scheduled at 6-8 weeks to exclude colorectal malignancy and a plan for reanastomosis three months later.
Making the case
Diverticular disease encompasses the spectrum from asymptomatic diverticula (sac-like protrusions of mucosa through the colonic wall) to diverticulosis (several diverticula) to diverticulitis diverticula that are inflamed, with microperforations that can lead to local abscesses and fistula. Diverticulosis is age-dependent. The prevalence is less than 5% at age 40 and rises to 65-80% at ages 85 and over.1 Females predominate slightly.
Diverticula are most commonly located on the left colon, especially the sigmoid.1 They're thought to be related to our modern low-fibre diet, which reduces stool bulk and slows colonic transit time, raising the intraluminal pressure. This causes herniation, through weaknesses in the muscular layer created by the penetrating arterial supply (vasa recta) to the mucosa.2 The diverticulum consists solely of mucosa i.e. it's a pulsion, or false, diverticulum.
Diverticulitis complicates 10-25% of diverticulosis cases.2 Inspissated food or fecal matter, or fecalith, trapped in the diverticulum abrades the mucosal lining and creates inflammation, or else becomes impacted and compromises the penetrating vessels, producing ischemia and microscopic perforation. These microperforations are then walled off by pericolonic fat and mesentery, often forming an abscess. Repeated episodes lead to more extensive damage. Subsequent healing by fibrosis can eventually cause a segmental stricture or obstruction. Macroperforations abut in either free perforation with generalized peritonitis or a pericolonic abscess. Erosion of the septic process into adjacent structures results in a fistula. Lastly, the injured vasa recta may rupture and cause a lower gastrointestinal bleed. Diverticular bleeding doesn't occur in conjunction with diverticulitis.
The presentation of diverticulitis is typically LLQ pain, fever and leukocytosis. There's often a history of a previous episode. Nausea, vomiting and altered bowel habits, usually diarrhea, may be associated. Fistula formation can result in recurrent urinary tract infections, pneumaturia, fecaluria and feculent vaginal discharge.
Physical examination elicits LLQ tenderness and, in uncomplicated diverticulitis, a tender mass. Perforation produces involuntary guarding, rigidity and percussion tenderness. Generalized peritonitis indicates rupture of a diverticulum or of a peridiverticular abscess. Rarely, colonic obstruction may develop after repeated episodes of diverticulitis, and a massively dilated cecum, signs of cecal necrosis (air in bowel wall on imaging) or a marked right lower quadrant tenderness warrant immediate surgical consultation.
The history and physical exam usually indicate the diagnosis. Lab features include an elevated white cell count and possible pyuria on urinalysis. Abdominal plain films will rule out free air or obstruction and abdominal CT can confirm clinical suspicion. CT is the optimal test: it localizes the inflammation, assesses complications and excludes other causes. Contrast barium enemas are contraindicated in suspected perforation because of the risk of extravasation use water soluble contrast instead. Sigmoidoscopy is occasionally performed when the diagnosis is in question. Colonoscopy is warranted 6-8 weeks after resolution to exclude malignancy.
Uncomplicated diverticulitis can be treated on an outpatient basis with a clear fluid diet and broad-spectrum antibiotics for 7-10 days. Avoid opiate analgesics, as they increase intracolonic pressure. Clinical improvement is expected within 48-72 hours. Following resolution, a high fibre diet is warranted. About 5% of patients will have a second attack within two years.1
More severe episodes require hospitalization with bowel rest, IV fluids and IV broad-spectrum antibiotics, e.g. metronidazole or clindamycin plus aminoglycoside or a third-generation cephalosporin. A nasogastric tube isn't required if there's no ileus, or obstruction.3 Most patients respond to medical therapy, though 15-30% may require surgery for generalized peritonitis, sepsis or other complications. Repeat episodes are associated with an increased risk of complications and morbidity. Elective surgery should be considered when the initial presentation is a second episode of diverticulitis or is complicated by an abscess, fistula, stricture or contained perforation.4
Brinderjit Kaila, MD, is a fourth-year gastroenterology fellow at the University of Calgary in Alberta.
Eldon A. Shaffer, MD, FRCPC is a professor of medicine in Gastroenterology, Dept. of Medicine at the University of Calgary
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