Giant sigmoid diverticulitis mimicking acute appendicitis

Abstract

Giant colonic diverticula are a rare manifestation of diverticular disease and there are fewer than 150 cases described in the literature. They may have an acute or chronic presentation or may remain asymptomatic and be found incidentally. As the majority (over 80%) of giant diverticula are located in the sigmoid colon, they usually present with left-sided symptoms but due to the variable location of the sigmoid loop, right-sided symptoms are possible. We describe the acute presentation of an inflamed giant sigmoid diverticulum with right iliac fossa pain. We discuss both the treatment options for this interesting condition and also the important role of computed tomography in the diagnosis and management of abdominal pain in elderly patients.

Case history

A 70-year-old man presented to the acute general surgical take with a 24-hour history of worsening right iliac fossa pain. On examination he was found to have guarding and percussion tenderness in the right iliac fossa with pyrexia and tachycardia. A laboratory blood analysis showed a leukocytosis and an elevated C-reactive protein level. A diagnosis of acute appendicitis was suspected but in view of the age of the patient and his co-morbidity (ischaemic heart disease and type 2 diabetes) an urgent computed tomography (CT) of the abdomen and pelvis with oral contrast was arranged (Fig 1). The scan showed a 6.5cm-diameter giant sigmoid diverticulum in the mid-sigmoid to the right of the midline within an area of moderate diverticulosis. The giant diverticulum showed contrast enhancement indicating active inflammation. There was no evidence of a paracolic abscess, perforation or appendicitis and a diagnosis of acute giant sigmoid diverticulitis was made. Our patient was assessed as being at high risk for a laparotomy and was treated with intravenous broad-spectrum antibiotics with anaerobic cover. After 72 hours his symptoms had settled and he was well enough to be discharged.

Figure 1.

Contrast computer tomography showing giant sigmoid diverticulum

Discussion

Giant colonic diverticula (GCD) are defined as having a minimum diameter of 4cm¹ and are a rare feature of diverticular disease. It is extremely rare for them to present with right iliac fossa pain as 81% are found in the sigmoid colon, which is usually located in the left iliac fossa.¹

The classical presentation of a giant diverticulum is that of a patient in the sixth or seventh decade,¹ with a history of vague or intermittent abdominal pain and a mobile, soft abdominal mass.² This may be accompanied by non-specific symptoms including fever, nausea, vomiting, constipation, diarrhoea or haemorrhage.

Literature suggests 15–20% of GCD patients present with complications (two-thirds of these with perforation)² and operative mortality is 5%. Surgery is therefore advocated even for asymptomatic patients² unless medically unfit for surgery. Surgical options include diverticulectomy or segmental colectomy. Conservative treatment should be reserved only for high-risk patients who are unlikely to tolerate major surgery.

GCD are most accurately evaluated with contrast CT although they can also be seen on a plain abdominal radiograph. There is only a limited role for ultrasound, colonoscopy or barium enema examination.

In this case, CT was crucial in making the diagnosis of giant sigmoid diverticulitis and excluding other right-sided pathology that may have required an operation (appendicitis, perforated caecal carcinoma). Over 80% of giant diverticula are located in the sigmoid colon, usually presenting with left-sided symptoms but due to the variable location of the sigmoid loop, right-sided symptoms are possible.

Because of the high complexity of elderly patients, abdominal CT is very helpful for supplementing clinical evaluation and assisting with diagnosis. Accurate clinical diagnosis of abdominal pain is inversely proportional to patient age.³ Older patients often present with vague non-specific complaints and hence a broad differential diagnosis should always be considered. Confounding factors in the elderly include increased risk of catastrophic vascular emergencies, delayed presentation and atypical symptoms, physical findings and laboratory values.³ Elderly patients presenting with abdominal pain are more than twice as likely to require surgery than young patients⁴ and have a 6–8-fold increase in mortality.⁴

Abdominal CT is highly sensitive in older patients presenting as acute surgical emergencies.⁵ Hustey et al found that the most common CT findings in older patients with acute abdominal pain were small bowel obstruction (18%), diverticulitis (18%), urolithiasis (10%), cholelithiasis (10%), abdominal neoplasms (8%) and pancreatitis (6%).⁵ By increasing diagnostic accuracy, abdominal CT has been shown to be a useful adjunct to aid clinical decision making in elderly patients with abdominal pain.