Does high body mass index obviate the need for oral contrast in emergency department patients?

High body mass index (BMI) values generally correlate with a large proportion of intra-peritoneal adipose tissue. Because intra-peritoneal infectious and inflammatory conditions manifest with abnormalities of the adipose tissue adjacent to the inflamed organ, it is presumed that with a larger percentage of adipose surrounding a given organ, visualization of the inflammatory changes would be more readily apparent. Do higher BMI values sufficiently enhance the ability of a radiologist to read a computed tomography (CT) of the abdomen and pelvis, so that the need for oral contrast to be given is precluded?

FORTY SIX PATIENTS WERE INCLUDED IN THE STUDY: 27 females, and 19 males. They underwent abdominal/pelvic CTs without oral or intravenous contrast in the emergency department. Two board certified radiologists reviewed their CTs, and assessed them for radiographic evidence of intra-abdominal pathology. The patients were then placed into one of four groups based on their body mass index. Kappa analysis was performed on the CT reads for each group to determine whether there was significant inter-rater agreement regarding contrast use for the patient in question.

There was increasingly significant agreement between radiologists, regarding contrast use, as the study subject's BMI increased. In addition, there was an advancing tendency of the radiologists to state that there was no need for oral or intravenous contrast in patients with higher BMIs, as the larger quantity of intra-peritoneal adipose allowed greater visualization and inspection of intra-abdominal organs.

Based on the results of this study, it appears that there is a decreasing need for oral contrast in emergency department patients undergoing abdominal/pelvic CT, as a patient's BMI increases. Specifically, there was statistically significant agreement, between radiologists, regarding contrast use in patients who had a BMI greater than 25.