The incidence of acute diverticulitis – common disease in Western countries – is increasing worldwide. Acute diverticulitis can be divided by its degree of severity into uncomplicated and complicated forms. Accurate diagnosis is a prerequisite for choosing optimal treatment and follow-up. Currently, the diagnosis is made using computed tomography imaging. Although the accuracy of computed tomography imaging in the diagnosis of acute diverticulitis is good, differential diagnostics can be challenging.

The purpose of this dissertation was to investigate the risk of colorectal cancer after computed tomography-verified acute diverticulitis with special interest in long-term follow-up. We also aimed to assess the usefulness of reassessment of computed tomography scans and the role of experience of radiologists in emergency settings in the diagnosis of acute diverticulitis. In addition, we aimed to create a risk score for acute diverticulitis to distinguish uncomplicated and complicated forms of the disease without using computed tomography imaging by evaluating risk factors for complicated acute diverticulitis.

We found that further colonic investigations were not needed after an attack of uncomplicated acute diverticulitis, as the risk of underlying colorectal cancer was low, although the risk was increased in the case of complicated disease in the short-term follow-up. No cases of colorectal cancer associated with acute diverticulitis were observed in the long-term follow-up. Reassessment of computed tomography reports in emergency settings changed the treatment or diagnosis in 5% of cases. The role of a radiologist’s experience was not statistically significant, and reports given by residents were comparable to reports given by consultants. Based on statistically significant risk factors of complicated acute diverticulitis, we created a novel risk score for acute diverticulitis that, without computed tomography imaging, accurately separated patients with a potentially severe disease from those without.