INTRODUCTION AND EPIDEMIOLOGY
Diverticular disease is increasingly common in industrialized nations, and the prevalence of diverticulosis increases with age: 5% in patients age <40 years, 30% by age 60, and >70% by age 85.1 Based on National Emergency Department Sample records from 2006 to 2013, evolving diverticulitis prevalence and management have resulted in a 27% increase in diverticulitis-related ED visits and a 105% increase in aggregated national cost, whereas ED admissions for diverticulitis decreased from 58% to 47% and surgical management decreased by 33%.2
The natural history of the disease appears to be more benign than previously believed. Only 15% of patients with diverticulitis develop complicated disease.3 Recurrence occurs in 20% to 30% of patients with diverticulitis treated conservatively.3,4 Although surgery played a prominent role in diverticulitis management in the past, most cases of diverticulitis can be managed medically, even with recurrent episodes. In one study following 2366 Kaiser Permanente patients hospitalized with acute diverticulitis and treated nonoperatively, 86% required no further inpatient care for diverticulitis during a 9-year follow-up period. Only 4% had a second recurrence. No patient with a second recurrence required an operation.5
Diverticula are small herniations at sites where the vasculature, called vasa recta, penetrates the circular muscle layer of the colon. Although true diverticula involve all layers of the colon wall, most acquired diverticula are considered false diverticula, involving only the mucosal and submucosal layers. Diverticula usually range from 5 to 10 mm, but can extend up to 20 mm in length. Diverticulitis occurs when inflammation develops and, in complicated diverticulitis, leads to translocation of bacteria, microperforation, and abscess or phlegmon formation.6
There are similar chemical and histologic changes seen in inflammatory bowel disease and irritable bowel syndrome, but no unifying mechanism has been demonstrated.6,7 Common bacterial pathogens are anaerobes, including Bacteroides, Clostridium, and Peptostreptococcus, as well as aerobic bacteria such as Escherichia coli, Enterococcus, Pseudomonas aeruginosa, and Klebsiella. While most GI infections are both anaerobic and aerobic, Bacteroides fragilis and E. coli are the dominant bacteria isolated.8
Altered bowel motility leads to high intraluminal colonic pressures and diverticula formation. The role of diet remains unclear. Smoking and obesity increase risk for diverticulitis, and an active lifestyle is said to decrease the risk. NSAIDs, opioids, and steroids increase the risk of perforation.6
In the United States, diverticular disease is almost exclusively a left-sided colon disease, specifically the descending and sigmoid colon. Right-sided disease accounts for only 2% to 5% of cases and is found predominantly in Asian populations.9
Classically, diverticulitis presents with left lower quadrant abdominal pain, fever, and leukocytosis. Patients with a redundant sigmoid colon, of Asian descent, or with right-sided disease may complain of right ...