Utility of CT oral contrast administration in the emergency department of a quaternary oncology hospital: diagnostic implications, turnaround times, and assessment of ED physician ordering.

Abstract

To compare studies with and without oral contrast on performance of multidetector computed tomography (CT) and the order to CT examination turnaround time in cancer patients presenting to the emergency department (ED). To the best of our knowledge, oral contrast utility has not previously been specifically assessed in cancer patients presenting to the emergency department. Retrospective review of CT abdomen examinations performed in oncology patients presenting to the emergency department during one month. CT examinations performed with and without oral contrast were rated by two consensus readers for degree of confidence and diagnostic ability. Correlations were assessed for primary cancer type, age, sex, chief complaint/examination indication, body mass index, intravenous contrast status, repeat CT examination within 4weeks, and disposition. Turnaround times from order to the start of the CT examination were calculated. The studied group consisted of 267 patients (127 men and 140 women) with a mean age of 56years and a mean body mass index of 27.8kg/m2. One hundred sixty CT examinations were performed without oral contrast, and 107 CT examinations were performed with oral contrast. There was no significant difference between cases with oral contrast and cases without oral contrast in the number of cases rated as "improved confidence" (odds ratio [OR] 0.54, 95% confidence interval [CI] 0.23-1.31, P=0.17), "improved diagnosis" (OR 0.58, 95% CI 0.20-1.64, P=0.3), "impaired confidence" (OR 3.92, 95% CI 0.46-33.06, P=0.21), or "impaired diagnosis" (OR 2.63, 95% CI 0.29-23.89, P=0.39). The turnaround time in the group receiving oral contrast (mean, 141min; standard deviation, 49.8min) was significantly longer than that in the group not receiving oral contrast (mean, 109.2min; standard deviation, 64.8min) with a mean difference of 31.8min (P<0.0001). On the basis of our findings and prior studies, targeted rather than default use of oral contrast shows acceptable diagnostic ability in the emergency setting for oncology patients. Benefit from oral contrast use is suggested in scenarios such as suspected fistula/bowel leak/abscess, hypoattenuating peritoneal disease, prior bowel surgery such as gastric bypass, and the absence of intravenous contrast administration. Improvement through the use of targeted oral contrast administration also supports the emergency department need for prompt diagnosis and disposition.