Assessment of acute abdominal pain: utility of a second cross-sectional imaging examination.

PURPOSE: To retrospectively determine how often a second cross-sectional imaging examination provides useful additional information or alters management of acute abdominal pain. MATERIALS AND METHODS: The research ethics board approved this study; the informed consent requirement was waived. Authors assessed imaging reports and clinical charts of adult patients who presented to the emergency department and underwent both computed tomography (CT) and ultrasonography (US) of the abdomen within 72 hours. A total of 255 patients fulfilled study criteria. The second examination was categorized as providing additional useful information, providing no additional useful information, or providing contradictory information. It was also noted whether the second examination was recommended because of findings of the first and whether the results of the second altered clinical management. Follow-up was available in 149 patients, and a definitive diagnosis was established. For these patients, it was determined whether either examination favored the correct diagnosis. Fisher exact test, one- and two-sample tests for equality of proportions with continuity correction, and the chi(2) test were used, where appropriate. RESULTS: In 85 patients (33.3%), findings of the second examination agreed with those of the first examination and provided additional information. In 153 patients (60.0%), findings of the second examination agreed with those of the first examination and provided no additional information. In 17 patients (6.7%), findings of the second examination were contradictory to findings of the first examination. The percentage of follow-up CT examinations that provided no additional useful information was significantly lower when recommended by the radiologist (38%) than when recommended by someone else (72%, P < .001). The percentage of follow-up US examinations that provided no additional useful information was significantly lower when recommended by the radiologist (42%) than when recommended by someone else (74%, P = .003). In the 149 patients in whom a final diagnosis was available, both sets of scans were correct in 87 patients (58.4%); only the second set of scans was correct in 43 (28.8%). Overall, findings of the second examination led to a change or could have led to a change in treatment of 23 patients (9.0%). CONCLUSION: A second examination is significantly more likely to be useful when performed because of radiologist recommendation.