Effect of oral contrast for abdominal computed tomography on emergency department length of stay.

Computed tomography of the abdomen and/or pelvis (CTAP) is frequently used in the emergency department (ED) allowing diagnosis of a variety of conditions, but requiring a prolonged period of preparation. To determine whether not requiring oral contrast for CTAP reduces ED length of stay (LOS). Retrospective cohort of adult patients visiting an academic ED over 13 weeks around a radiology protocol change. Before the change, many CTAPs required oral contrast; thereafter, oral contrast was not required. LOS was compared before and after the change among all adult ED patients. Among patients undergoing CTAP, adjusted LOS and time to CTAP were compared using multivariate linear regression. 20,464 adult ED visits occurred over the study period, including 1,806 where a CTAP was performed. Oral contrast usage decreased from 42.5% of CTAP to 12.2% (difference 30.3%, 95% confidence interval 38.7% to 46.3%). There was no change in LOS among all ED visits. Among ED visits where a CTAP was performed, median time to CTAP decreased by 27 min and median LOS decreased by 30 min. Adjusted LOS decreased from 324 min (312-337) to 297 min (285-309). Not routinely requiring oral contrast for CTAP in the ED is associated with a half-hour reduction in LOS among all patients undergoing CTAP.