Caecal diverticulitis is rare in Western countries and has a higher incidence in Oriental populations [1
]. In Western countries, 85% of all diverticula occur in the descending and sigmoid colon, whereas the incidence of right-sided diverticular disease in Oriental countries can be up to 71%. Solitary caecal diverticulae are believed to be congenital in origin and arise as an out-pouching of the caecum at 6 weeks gestation [1
]. As they comprised all layers of the colonic wall, including the muscularis layer, they are therefore designated 'true' diverticula. In contrast, 'false' diverticula are often multiple and consist of herniations of mucosa and submucosa through the circular muscle layer, at the points of penetration of the vasa recta.
The pre-operative diagnosis of right sided colonic diverticulitis is very difficult without radiological imaging [4
]. Some series have suggested that there are certain clinical features which may help in differentiating the condition from acute appendicitis [3
]. These include:
• relatively longer history of right iliac fossa pain
• relative lack of systemic toxic signs despite duration of symptoms
• nausea and vomiting are not common
• symptoms usually begin and remain localised in the right iliac fossa, rather than initially presenting with vague central abdominal pain like appendicitis
However, despite these subtle signs, the condition is usually clinically indistinguishable from acute appendicitis and the correct diagnosis is often made during exploration for suspected appendicitis [4
Because of our strong clinical assumption that our patient had acute appendicitis no pre-operative imaging studies were performed. Both ultrasound (US) [7
] and computer tomography (CT) [9
] have been shown to be accurate in diagnosing right side diverticulitis pre-operatively.
The principal US appearances of an inflamed diverticulum are of a round hypo-echoic structure arising from a segment of thickened colonic wall [7
]. Stronger echoes arising from the structure may represent gas or a faecolith within the diverticular lumen. These features, especially if a normal sonographic appearance of the appendix is found, are highly specific for right-sided diverticulitis. Chou et el [7
] reviewed 934 patients with clinically indeterminate right-sided abdominal pain who went on to have abdominal ultrasound. They reported that ultrasound could differentiate between right-sided diverticulitis and acute appendicitis with 100% accuracy. They showed ultrasound to have a sensitivity of 91.3%, a specificity of 99.8% and an overall accuracy of 99.5% in the diagnosis of caecal diverticulitis [7
]. False-negative tests were the result of either missing a small diverticulum, suboptimal examination in obese patients or those with abdominal tenderness or the view being obscured by overlying bowel gas [7
]. Although ultrasound is non-invasive and widely available, operator dependency may limit its accuracy, especially in Western countries where experience of caecal diverticulitis is limited.
Helical CT scanning with intravenous contrast can accurately demonstrate features of acute right sided diverticulitis [9
]. Features of caecal diverticulitis on CT are similar to those of left sided diverticulitis and include colonic wall thickening, pericolic fat infiltration, associated abscess formation and extraluminal air denoting perforation. However, these features may also be present with other right sided colonic pathology, such as caecal carcinoma. In approximately 10% of patients diverticulitis is reported to be indistinguishable from carcinoma on CT. Jang et al showed that the presence of an inflamed diverticula and a preserved enhanced pattern of the thickened colonic wall were the two most reliable characteristics to differentiate diverticulitis from caecal carcinoma [9
]. In addition a recent study found that visualisation of pericolonic lymph nodes adjacent to the colonic wall lesion was more commonly seen in patients with colonic malignancy [10
]. Some authors have suggested that CT scanning is useful in patients with an atypical history for appendicitis, older patients at risk of caecal malignancy and those who have undergone previous appendicectomy [10
Recently magnetic resonance imaging has been shown to be useful in diagnosis right sided diverticulitis [11
]. It may be particularly useful in patients who have equivocal ultrasound features or in those where it is important to avoid ionising radiation, such as young or pregnant patients.
The surgical management of non-perforated caecal diverticulitis is controversial. Table outlines the advantages and disadvantages of each potential management option. If diagnosed confidently pre-operatively, conservative management with intravenous antibiotics, in a similar fashion to the way left-sided diverticulitis is initially managed has the benefit of avoiding laparotomy. If the condition is diagnosed intra-operatively during exploration for appendicitis, conservative management can still be applied after completing the appendicectomy. However, this course of management risks missing an inflammatory carcinoma of the right colon and is more valid in an Asian population where benign pathology is more common than neoplastic disease.
Advantages and disadvantages of various management approaches in treatment of symptomatic right-sided diverticulitis
Surgical resection varies from isolated diverticulectomy, ileocaecal resection and right hemicolectomy. Laparoscopic diverticulectomy has also been described in the management of right side diverticulitis [12
]. A recent review of 85 patients with caecal diverticulitis, by Fang et al [13
], recommend an aggressive resection in treatment of the disease. Less than 40% of their patients were successfully treated conservatively. In the group of patients that had appendicectomy as the only surgical intervention, 29.2% developed recurrent right side diverticulitis and 12.5% required subsequent right hemicolectomy [13
Other pathology may mimic right side diverticulitis including colonic malignancy, inflammatory Crohn's mass, perforated foreign body reaction or ileocaecal tuberculosis. In our case, the intra-operative findings were suspicious of an underlying carcinoma. In this situation a right hemicolectomy with adequate cancer clearance is the correct surgical procedure. Other indications for aggressive surgical resection include multiple diverticulae or a large caecal phlegmon.
A novel idea, reported by Chui et al [14
], to differentiate caecal diverticulitis from caecal carcinoma is the use of intra-operative caecoscopy. During laparotomy, an endoscope is passed through the appendix stump to visualise the caecal mucosa. Although it has only been successfully applied to five patients, its benefits are that if caecal malignancy is excluded the extent of surgical resection can be reduced in uncomplicated cases.