The primary value of abdominal X-rays is to rule out pneumoperitoneum or to assess for a possible obstruction; therefore plain films of the abdomen should include supine and upright or left lateral decubitus views. Computed tomography (CT) scan is often the evaluation of choice in the face of acute abdominal pain, so in many centers, the plain abdominal film is rarely used.

Barium or water-soluble contrast studies have their proponents for utilization; however, CT scans provide a significantly more thorough evaluation, making it the preferred imaging study in many centers (Fig. 22.1 ). Nonetheless, due to costs, some clinicians will utilize CT scan only if there is clinical suspicion of an abscess or other complicating feature for which an alternative to standard bowel rest and antibiotics might be applied. A water-soluble contrast study can evaluate the lumen of the bowel if there is concern about distal bowel obstruction. It may be an important part of the assessment for the possible use of a colonic stent if malignant disease is suspected.

In most centers, contrast studies, if used at all, are used in a limited fashion to evaluate the anatomy of the colon prior to an operation.

An important advantage of a CT scan is the ability to document diverticulitis, even if uncomplicated, when the diagnosis is in doubt.

It has been demonstrated that CT can recognize and stratify patients according to the severity of their disease.

Preliminary studies utilizing magnetic resonance imaging (MRI) colonography have shown a high correlation with CT findings in patients with diverticular disease without exposure to ionizing radiation. Three-dimensional rendered models and virtual colonoscopy can be performed only in the nonacute setting. These comprehensive 3-D models, rather than barium enema, may have a role in presurgical planning with concurrent assessment of the residual colon.

Transrectal ultrasound (TRUS) has been utilized in the evaluation of diverticular disease in conjunction with transabdominal ultrasound (TAUS). TRUS may prove to be a useful adjunct in selected cases of rectosigmoid diverticulitis and perirectal involvement by diverticular disease in centers where CT scanning is not readily available.

Endoscopy in the face of acute diverticulitis must be undertaken with extreme caution due to risk of perforation and decreased chance of successful cecal intubation. Generally, in the absence of an urgent indication, colonoscopy should be delayed until resolution of the acute episode is complete.

In the case of elective colonoscopy, the unexpected finding of acute diverticulitis (manifested as erythema, edema, pus, or granulation tissue at a diverticular opening) is distinctly unusual, occurring in just 0.8 % of patients. Treatment with antibiotic therapy for such findings is generally unnecessary as follow-up has shown that symptoms of diverticulitis do not develop following the colonoscopy.

In many ways, the distinction between chronic diverticulitis and noninflammatory diverticular disease relies upon the pathologist, while the distinction between noninflammatory diverticular disease and IBS relies on the diagnostic acumen of the clinician and the long-term outcomes of resection. Due to the prevalence of diverticular disease, many patients with IBS will have concomitant diverticular disease. However, due to the fact that diverticular disease is most commonly asymptomatic, the presence of diverticulosis in these patients will often not be the source of their symptoms but rather just a source of confusion in the differential. It is helpful to be familiar with the Rome II criteria (Table 22.3 ) for the diagnosis of IBS in order to sort through this differential.

Distinguishing diverticular disease from cancer can be difficult and occasionally a resection is necessary. Findings on barium enema (BE) that supports a diagnosis of diverticular disease include preservation of the mucosa, long strictures, and the presence of diverticula. A BE can also assess the extent of the diverticulosis prior to resection. Colonoscopy can frequently resolve this issue, but it is not always possible due to acute angulations or narrowing of the lumen. CT evaluates the entire abdomen, which can identify concurrent disease and may give clues to underlying colonic pathology.

The increasing incidence of colonic neoplasia with increasing age parallels that of diverticular disease. Polyps and cancer must be considered whenever a diagnostic workup for diverticular disease is begun.

Crohn’s disease can be a particularly difficult diagnosis to make. Both Crohn’s and diverticular disease may present with similar complications including fistulas, phlegmons, and abscesses. Rectal involvement, anal disease, extracolonic signs, and bleeding suggest Crohn’s disease. Recurrent “diverticulitis” requiring a repeat resection should always raise the question of possible Crohn’s disease.

Endoscopy can be an important adjunct in differentiating IBD, ischemic colitis, and other forms of colitis although caution must be used in the acute setting. A major advantage of the CT scan is the ability to evaluate for many of the other potential differentials including appendicitis and gynecologic and urologic disease.

There continues to be some debate as to the issue of recurrence in patients younger than 50 years old. It does appear that there is an increased incidence in younger patients presenting with diverticulitis.

Historically, diverticular disease in patients less than age 50 has been described as more virulent and with more serious complications.

Despite the increased number of younger patients with the disease, its virulence does not appear to be any different compared to older counterparts. It is now doubtful that age itself should be a primary consideration in the decision to operate.

Young patients with diverticular disease are more commonly male and obese and have a higher incidence of right-sided diverticulitis.

Young patients undergoing operation were frequently misdiagnosed preoperatively with appendicitis being the most common misdiagnosis.

Many recommend that patients less than age 50 have an elective resection after a single episode of acute disease.

Recent evidence is mixed and supports a more conservative trend to recommending resection for uncomplicated diverticulitis.

Some have recommended elective resections at a younger age to avoid the increased morbidity and mortality associated with urgent or emergent surgery in the elderly (0 % vs. 34.9 %). Some recommendations for elective resection in the young patient are based on cost savings related to definitive surgical management vs. the higher costs of ongoing medical treatment for recurring disease. These types of recommendations assume a high risk of recurrent disease.

There is evidence that diverticular disease in young patients is changing. It is not as rare as in the past and continues to become more prevalent. And recent evidence suggests there is no increased risk of complications from diverticular disease in the young. Based on these findings, resection following a single episode of diverticulitis is not recommended.

Current recommendations for resection are based on the predicted risk of developing a serious complication that would lead to emergency surgery with increased morbidity and mortality. To improve management, we must become better at predicting who is at risk for recurrent disease. Age alone does not appear to be a reliable factor. The use of CT to identify “severe” or “complex” diverticular disease seems most promising.

Giant diverticula of the colon are rare entities associated with sigmoid diverticular disease. They are generally pseudodiverticula with inflammatory rather than colonic mucosal walls. They usually arise off of the antimesenteric border of the sigmoid colon.