210 differentiate between post-diverticulitis stenosis or cancer; diverticular bleeding is the most common cause of recurrent rectal blood loss, but again cancer should be ruled out by a colonoscopy; and pneumaturia is pathognomic for a colo- vesical fistula, usually a CT scan will reveal its pathway. Furthermore, a generalized peritonitis is only diagnosed by physical examination. The combination of the following symptoms should be suspected: an ill patient with fever, absence of peristalsis, very tender abdomen on palpation, relief pain, and défènce musculair. A CT scan is often mandatory in uncovering its cause and confirming the absolute indication for surgery. When elective surgery for diverticular disease is considered, indications are mainly determined by the impact of symptoms on patients’ lives. Complications such as stenosis, fistula, or recurrent diverticular bleeding are clear indications for an elective sigmoid resection, but also the prevention of perforated diverticulitis by performing an elective sigmoid resection has been standard policy for several decades. Recently, these recommendations have been challenged because new data on the natural history of diverticulitis has shown that most perforations do not occur after recurrences, but at the first attack of acute diverticulitis [11]. Furthermore, conservative management of recurrent non-perforated diverticulitis is associated with low rates of morbidity and mortality. These new insights resulted in a more individualized and conserva- tive approach to mild diverticular disease, making the extent of subjective complaints even more important [2, 12]. Imaging The original Hinchey classification was based on both clinical and surgical findings. Since then diagnostic tools have widely been improved and new modalities have been developed. The usual tests performed at the acute phase of diverticular disease are the following: water-soluble contrast enema, CT scan, and ultrasound (US). Although US has been proven as a noninvasive, readily available, and well-performing tool for the diagnosis of acute diverticulitis, its drawbacks are the dependency on the level of the examiner’s competence and the fact that images are unreadable for other physicians [13]. In today’s clinical practice regarding diverticular disease, CT scans enhanced with intravenous and intrarectal contrast have, because of their superior sensitivity and specificity up to 100%, replaced contrast enemas as the most important imaging modality [14, 15]. Especially when an associated abscess is suspected, a CT scan can be very helpful to demonstrate its presence. Also, the possibility of direct percutaneous drainage makes it a valuable attribute in the treatment of complicated diverticular disease [16]. In the case of diverticular bleeding, a CT scan enhanced with intravenous contrast (CT angio) may demonstrate a contrast Int J Colorectal Dis (2012) 27:207–214 blush, a limitation is that blood loss has to be at least 2 ml/min. Furthermore, it has to be considered that 80% of all diverticular bleeding is self-limiting. The role of interventional radiology is yet to be determined, occasional successes of highly selective arterial embolization are described [17]. A colonoscopy is indicated when there is doubt about cancer, persisting or recurrent complaints in the left lower quadrant, and suspicion of a stenosis or recurrent blood loss. Colonoscopy enables biopsies for histological diagnosis, and cessation of diverticular bleeding may be attempted by endoscopic measures, such as clipping, coagulation, or adrenaline injections [18]. Follow-up colonoscopy for ruling out malignancy is usually performed 6 weeks after an episode of acute diverticulitis. Routine colonoscopy divulges the majority finds of asymptomatic diverticular disease. In recent years, magnetic resonance imaging (MRI) has gained popularity, because it lacks the ionizing radiation of a CT scan, yet matches its sensitivity and specificity [19]. Additional advantages of MRI over CT scan are its better visualization of fistulae and the possibility of virtual colonoscopy, thereby making invasive colonoscopy unnecessary. To current date, the availability of the MRI and experienced radiologists are often limited and therefore not suitable for routine use. The wide use of CT scans initiated modifications to the Hinchey classification, but also several new radiological classifications for diverticular disease were developed. Kaiser et al. have published specific CT findings per modified Hinchey stage (see Table 2), resulting in a guideline for objective observation and reporting of CT scans [20]. The publications on the role of CT scans in diverticular disease by Ambrosetti et al. allocate diverticulitis into severe or moderate disease (see Table 5). In this approach, the CT scan provides the physician guidance in the treatment of acute complications, as well as a prognostic factor in the development of chronic complications after a first conserva- tively treated episode [21]. Treatment The wide spectrum of diverticular disease warrants a differen- tiated approach to the different manifestations. Treatment Table 5 CT findings by Ambrosetti et al. CT findings by Ambrosetti et al. [21] Moderate diverticulitis Severe diverticulitis Localized sigmoid wall thickening (<5 mm) Pericolic fat stranding Abscess Extraluminal air Extraluminal contrast