Diagnostic imaging is increasingly used in patients with suspected appendicitis, with increased costs and concerns about exposure to ionising radiation. Indications suggest that routine imaging is associated with a higher detection rate and treatment of potentially resolving appendicitis. The efficiency of routine imaging compared with in-hospital observation and selective imaging is not well studied.
The proportions of negative appendectomy and treatments for appendicitis are studied in 1068 patients with intermediate suspicion of appendicitis, indicated by an Appendicitis Inflammatory Response (AIR) score sum of five to eight points, randomly allocated by opaque sealed envelopes to early routine diagnostic imaging (Imaging group, n=543) or re-assessment after 4–8 hours inhospital observation followed by selective diagnostic imaging (Observation group, n=525). Some 21 hospitals in Sweden participated in this multicentre study.
The Imaging and Observation groups had the same proportion of negative appendectomies (6·5% in both, difference 0·03%, CI –3·0%–3·1%, p=0·98) but routine imaging was associated with an increased proportion of patients treated for appendicitis (53·4% vs 46·3%, difference 7·1%, CI 1·0–13·2%, p=0·020). As secondary outcomes, the Imaging group had shorter time to surgery (median 13·7 hours vs 15·5 hours, p<0·01), but no difference in admissions, number of perforations or length of hospital stay.
Patients with suspected appendicitis and equivocal clinical findings do not benefit from early routine diagnostic imaging compared with re-assessment after observation and selective imaging. The latter is associated with fewer operations for non-perforated appendicitis which supports the hypothesis of resolving appendicitis.